Lighting system Number:7,122,825 from the United States Patent and Trademark Office (PTO) owispatent

Title: Lighting system

Abstract: Semiconductor light-emitting devices are provided. The semiconductor light-emitting devices include a substrate and a crystal layer selectively grown thereon at least a portion of the crystal layer is oriented along a plane that slants to or diagonally intersect a principal plane of orientation associated with the substrate thereby for example, enhancing crystal properties, preventing threading dislocations, and facilitating device miniaturization and separation during manufacturing and use thereof.

Patent Number: 7,122,825 Issued on 10/17/2006 to Okuyama,   et al.

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Inventors:	Okuyama; Hiroyuki (Kanagawa, JP), Doi; Masato (Kanagawa, JP), Biwa; Goshi (Kanagawa, JP), Oohata; Toyoharu (Kanagawa, JP), Kikutani; Tomoyuki (Kanagawa, JP)
Assignee:	Sony Corporation (Tokyo, JP)
Appl. No.:	11/093,795
Filed:	March 30, 2005

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Related U.S. Patent Documents

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	Application Number	Filing Date	Patent Number	Issue Date
	10062687	Jan., 2002	6924500
	PCT/JP01/06212	Jul., 2001

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Foreign Application Priority Data

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Jul 18, 2000 [JP]			2000-218101
Jul 18, 2000 [JP]			P2000-217508
Jul 18, 2000 [JP]			P2000-217663
Jul 18, 2000 [JP]			P2000-217799
Jul 18, 2000 [JP]			P2000-218034
Jun 29, 2001 [JP]			2001-200183

Current U.S. Class:	257/13 ; 257/103; 257/E33.003
Current International Class:	H01L 29/20 (20060101); H01L 31/036 (20060101)
Field of Search:	257/15,22,76,E33.003,E33.025,E33.026 372/5,43.01,44.011

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References Cited [Referenced By]

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U.S. Patent Documents

	5814839		September 1998		Hosoba
	5981977		November 1999		Furukawa et al.
	6320209		November 2001		Hata et al.
	6924500		August 2005		Okuyama et al.

Foreign Patent Documents

	09129974		May., 1997		JP
	10312971		Nov., 1998		JP

Other References

Tachibana et al., "Selective growth of InGaN quantum dot structures and their microphotoluminescence at room temperature," May 29, 2000, Applied Physics Letters, vol. 76, No. 22, pp. 3212-3214. cited by examiner.

Primary Examiner: Whitehead, Jr.; Carl
Assistant Examiner: Dolan; Jennifer M
Attorney, Agent or Firm: Bell, Boyd & Lloyd LLC

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Parent Case Text

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CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent application Ser. No. 10/062,687, filed on Jan. 30, 2002, now U.S. Pat. No. 6,924,500, the disclosure of which is herein incorporated by reference, which is a continuation of International Application No. PCT/JP01/06212 with an international filing date of Jul. 18, 2001, and which claims priority to Japanese Patent Application No. P2000-218034 filed on Jul. 18, 2000; Japanese Patent Application No. P2000-217663 filed on Jul. 18, 2000; Japanese Patent Application No. P2000-217508 filed on Jul. 18, 2000; Japanese Patent Application No. P2000-217799 filed on Jul. 18, 2000; Japanese Patent Application No. P2000-218101 filed on Jul. 18, 2000; and Japanese Patent Application No. P2001-200183 filed on Jun. 29, 2001, the above-referenced disclosures of which are herein incorporated by reference.

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Claims

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The invention is claimed as follows:

1. A lighting system comprising: a plurality of semiconductor light-emitting device arranged so as to emit light in response to a signal, each of the semiconductor light-emitting devices comprising a substrate including a substrate surface positioned along a substrate surface plane, a crystal layer comprising an approximately hexagonal prismoid, having a face oriented about an S-plane, and a top region oriented about a C-plane, and a layer of a first conductivity type, an active layer, and a layer of a second conductivity type each formed along at least a portion of the approximately hexagonal prismoid.

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Description

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BACKGROUND OF THE INVENTION

The present invention generally relates to semiconductor devices. More specifically, the present invention relates to semiconductor light-emitting devices and processes for producing same.

Among known semiconductor light-emitting devices is one which consists of a low-temperature buffer layer, an n-side contact layer of Si-doped GaN, an n-side cladding layer of Si-doped GaN, an active layer of Si-doped InGaN, a p-side cladding layer of Mg-doped AlGaN, and a p-side contact layer of Mg-doped GaN, which are sequentially formed on top of the other over the entire surface of a sapphire substrate. Commercial products of such structure, available in large quantities, are blue and green LEDs (Light-Emitting Diodes) which emit light with wavelengths ranging from 450 nm to 530 nm.

Growing gallium nitride crystal on a sapphire substrate is a common practice. The sapphire substrate used for this purpose is usually one which has the C-plane (i.e., the (0001) plane in accordance with Miller indices of a hexagonal crystal system) as the principal plane. Consequently, the gallium nitride layer formed on the principal plane also has the C-plane, and the active layer, which is formed parallel to the principal plane of the substrate, and the cladding layers holding the active layer between them are also parallel to the C-plane. The semiconductor light-emitting device having crystal layers sequentially formed on the basis of the principal plane of the substrate has a smooth surface desirable for the formation of electrodes, due to the smoothness of the principal plane of the substrate.

A disadvantage of growing gallium nitride on a sapphire substrate is that dislocations may densely exist in the crystals due to lattice mismatch between them. Attempts have been made to eliminate defects in the grown crystals by forming a low-temperature buffer layer on the substrate. Japanese Patent Laid-open No. Hei 10-312971 discloses the combination with epitaxial lateral overgrowth (ELO) for reduction in crystal defects.

Also, Japanese Patent Laid-open No. Hei 10-321910 discloses a semiconductor light-emitting device, wherein the light-generating region extends vertically to the principal plane of the substrate in a hexagonal prismatic structure which is formed on the substrate such that its (10--10) or (1 100) M-plane is vertical (i.e., substantially perpendicular) to the principal plane of the substrate. The active layer, vertical to the principal plane of the substrate, is known to be effective in suppressing defects and dislocations due to lattice mismatch with the substrate and reducing strain due to difference in the coefficient of thermal expansion.

Moreover, Japanese Patent Laid-open No. Hei 8-255929 discloses a process for producing a light-emitting device. The process consists of forming, on a substrate, a layer of gallium nitride compound semiconductor of one conductivity type, covering part of the layer with a mask, forming, on the uncovered part, a layer of gallium nitride compound semiconductor (including a layer of another conductivity type) by selective growth, and forming a p-electrode and an n-electrode.

The technique of forming a hexagonal prismatic structure vertical to the principal plane of the substrate as disclosed in Japanese Patent Laid-open No. Hei 10-321910 requires that the film obtained by HVPE (hydride vapor phase epitaxy) should be followed by dry etching to give the (10--10) or (1 100) M-plane. Unfortunately, dry etching inevitably damages the crystal face. In other words, dry etching deteriorates the characteristic properties of crystals despite its effect of suppressing threading dislocations from the substrate. Further, an additional production step or process stage is required to perform dry etching.

It is known that selective growth on the C+-plane of the sapphire substrate gives a crystal layer with sharp peaks surrounded by the (1 101) plane or the S-plane (See Japanese Patent No. 2830814, paragraph 0009 of specification). The layer thus obtained is not flat enough for the electrode to be formed thereon. Therefore, it has never been used for electronic devices and light-emitting devices, and is merely used as an underlying layer of crystal structure for further selective growth.

Any device having a surface parallel to the principal plane of the substrate needs a flat surface for good crystal properties. As the result, it is usually constructed such that the electrodes spread horizontally. A disadvantage of this structure is that the horizontally spread electrodes make for extremely difficult and time-consuming work because one must separate miniature chips without cutting the horizontally spread electrodes. Moreover, the sapphire substrate and nitride (such as GaN) are so hard that they are difficult to cut and require a cutting allowance of about 20 .mu.m (i.e., micrometers), thereby making it even more difficult to cut the miniature chips.

Additionally, a problem with a light-emitting device in which the principal plane of the substrate is a C+-plane and the active layer of gallium nitride is formed parallel to the principal plane of the substrate is that there is only one bond from gallium atoms to nitrogen atoms in the C+-plane and hence, nitrogen atoms easily dissociate from the crystal face of the C+-plane, thereby making it difficult for the effective V/III ratio to be large, which in turn prevents improvement in performance of crystals constituting the light-emitting device.

The technology disclosed in Japanese Patent Laid-open No. Hei 8-255929 has an advantage of using selective growth which obviates the necessity of etching, such as reactive ion etching. However, it presents difficulties in forming the n-electrode accurately because large production steps occur in its vicinity after the mask layer has been removed. A disadvantage of forming the active layer parallel to the principal plane of the substrate, as in the light-emitting device disclosed in Japanese Patent Laid-open No. Hei 8-255929, is that the end of the active layer is exposed to air, thereby resulting in oxidation and deterioration of the active layer.

It is known that an LED device can be used as a light source for large display (such as projection display). To this end, it is important for LED devices to have higher brightness, better reliability, and lower production costs. The brightness of LED devices is governed by two factors: the internal quantum efficiency, which depends on the crystal properties of the active layer; and the light emergence efficiency, which is a ratio of light which has escaped from the device to light which has been generated in the device.

In general, a light-emitting diode has a light-generating region, the typical structure of which is shown in FIG. 1. The major parts of the light-generating region include an active layer 400 of, typically, InGaN, a first conductive layer 401 and a second conductive layer 402 (which hold the active layer 400 between them), and a reflecting film 403 (which also functions as an electrode) on the second conductive layer 402 opposite to the active layer 400, with the interface between the reflecting film 403 and the second conductive layer 402 functioning as a reflecting plane 404. Part of the light generated by the active layer 400 emerges directly from the light emerging window 405 in the first conductive layer 401, and part of the light advancing toward the second conductive layer 402 is reflected by the reflecting plane 404 and the reflected light advances toward the light emerging window 405 in the first conductive layer 401.

A disadvantage of the above-mentioned light-emitting diode of ordinary structure is that light generated by the active layer 400, however efficient it might be, cannot be extracted from the device due to total reflection that takes place at an interface between the device and the outside, between the device and the transparent substrate, and/or between the transparent substrate and the outside. In other words, light incident to the interface at an angle smaller than the critical angle is subject to total reflection. The critical angle depends on the refractive indices of the two materials forming the interface. In the light-emitting diode of surface emitting type which has the reflecting plane 404 and the light emerging window 405 parallel to each other as shown in FIG. 1, the light which has undergone total reflection at an angle smaller than the critical angle undergoes total reflection continuously between the reflecting plane 404 and the light emerging window 405. Hence, such light cannot be extracted as an effective output.

Attempts have been made to improve light emergence efficiency by forming a convex or a slope which changes the optical path in the device, so that the convex or slope functions as the reflecting plane which permits light to emerge efficiently. This technique, however, is not readily applicable to the GaN semiconductor which is used for blue or green LEDs. At present, it is believed that forming a sophisticated shape in an extremely small region is not known.

A sectional view of a light-emitting device of surface emitting type is shown in section in FIG. 2. It is formed on a substrate for growth 500 of sapphire. On the substrate 500 are sequentially formed a first conductive layer 501 of gallium nitride semiconductor, an active layer 502 of gallium nitride semiconductor, and a second conductive layer 503 of gallium nitride semiconductor, all parallel to the principal plane of the substrate. The active layer 92 and the second conductive layer 503 are partly removed such that an opening 506, whose bottom penetrates into the first conductive layer 501, is formed. In the opening 506, a first electrode 504 is formed such that it connects to the first conductive layer 501. A second electrode 505 is formed on the second conductive layer 503, thereby connecting to the second conductive layer 503.

A simple way to meet requirements of the light source for large displays is to increase the device size according to the desired brightness. However, the optical design limits the size of the light-generating region, which presents difficulties in producing a device having high brightness as well as a large light-generating region. Moreover, the active region in the device is also limited by the arrangement of the light emerging window and the electrodes for efficient current injection. At present, therefore, the requirement for high brightness is met by injecting more than the specified current into the actual device. However, increased current injection impairs device reliability.

On the other hand, decreasing the device size of light-emitting diode is expected to reduce production cost through improvement in yields. There is a strong demand for size reduction in the area where LEDs in an array having individual pixels for display. However, size reduction leads to an increased load per unit area, which contradicts the above-mentioned requirements for high brightness and high reliability.

Moreover, if the device size is to be reduced below tens of micrometers or less, the region for the active layer is greatly limited by the electrodes 504 and 505 (shown in FIG. 2) and the device separating grooves. The region where the conductive layers 503 and 501 come into contact with the electrodes 505 and 504 should be as large as possible to keep resistance low. However, enlarging the electrodes reduces the area through which light emerges from the active region, which leads to reduced brightness.

A need, therefore, exists to provide a micro-size light-emitting device with efficient light emergence, high brightness, minimum load on the active layer and controlling threading dislocations from the substrate that can be produced under optimal process conditions.

SUMMARY OF THE INVENTION

The present invention relates to semiconductor light-emitting devices and methods of producing same. The light-emitting devices of the present invention include a crystal structure formed by selective growth and oriented about a crystal plane with respect to a substrate such that the light-emitting properties can be enhanced.

Applicants have discovered that the light-emitting devices of the present invention can be produced, for example, under optimal process conditions, such as, without requiring additional production steps or process stages, by controlling threading dislocations from the substrate and maintaining desirable crystal properties, thereby also protecting the active layer from deterioration. In this regard, the light-emitting devices of the present invention are desirably reliable with minimum load on the active layer (e.g., light-generating region) and can provide an enhanced level of brightness due to, for example, the improved light emergence efficiency.

To this end, in an embodiment of the present invention, a semiconductor light-emitting device is provided. The semiconductor light-emitting device includes a substrate including a substrate surface positioned along a substrate surface plane, a crystal layer having a crystal surface oriented along a crystal surface plane diagonally intersecting the substrate surface plane, and a first conductive layer, an active layer, and a second conductive layer each formed along at least a portion of the crystal surface.

In an embodiment, the crystal layer is a wurtzite crystal structure.

In an embodiment, the crystal layer is composed of a nitride semiconductor material.

In an embodiment, the crystal layer is formed by selective growth on the substrate with a material layer capable of growth interposed therebetween.

In an embodiment, the material layer capable of growth is selectively removed during selective growth to form the crystal layer.

In an embodiment, the semiconductor light-emitting device further includes a masking layer having an opening through which the crystal layer is selectively grown.

In an embodiment, the crystal layer is formed by selective growth such that the crystal layer extends laterally from the opening in the masking layer.

In an embodiment, the substrate plane is a C-plane.

In an embodiment, the crystal surface plane includes at least one of a S-plane and a (11 22) plane.

In an embodiment, the crystal surface plane includes a plane having a plane orientation inclined at an angle ranging from about 5 to about 6 degrees with respect to at least one of a S-plane and a (11 22) plane.

In an embodiment, current is injected into the active layer.

In an embodiment, active layer includes InGaN.

In an embodiment, the crystal layer is a substantially symmetrical hexagonal structure.

In an embodiment, a portion of the crystal surface is oriented along a C-plane and positioned centrally along the crystal structure with respect to a second portion of the crystal surface that is oriented along the crystal surface plane which diagonally intersects the substrate surface plane.

In another embodiment according to the present invention, an image display unit is provided. The image display unit includes a number of semiconductor light-emitting devices arranged so as to emit light in response to a signal, each of the semiconductor light-emitting devices having a substrate including a substrate surface positioned along a substrate surface plane, a crystal layer including a crystal surface oriented along a crystal surface plane diagonally intersecting the substrate surface plane, and a first conductive layer, an active layer, and a second conductive layer each formed along at least a portion of the crystal surface.

In yet another embodiment according to the present invention, a lighting system is provided. The lighting system includes a number of semiconductor light-emitting devices, each of the semiconductor light-emitting devices having a substrate including a substrate surface positioned along a substrate surface plane, a crystal layer including a crystal surface oriented along a crystal surface plane diagonally intersecting the substrate surface plane, and a first conductive layer, an active layer, and a second conductive layer each formed along at least a portion of the crystal surface.

In an embodiment, each of the semiconductor light-emitting devices in the lighting system are arranged so as to emit light in response to an identical signal.

In a further embodiment according to the present invention, a process for producing a semiconductor light-emitting device is provided. The process includes the steps of providing a substrate including a substrate surface oriented along a substrate surface plane, forming a crystal seed layer on the substrate surface, forming a masking layer on the crystal seed layer, wherein the masking layer includes an opening, forming a crystal layer by selective growth of the crystal seed layer through the opening of the masking layer, wherein the crystal layer includes a crystal layer surface oriented along a crystal layer plane that diagonally intersects the substrate surface, and forming each of a first conductive layer, an active layer, and a second conductive layer along at least a portion of the crystal layer surface.

In an embodiment, the substrate surface plane comprises a C-plane.

In an embodiment, the process for producing a semiconductor light-emitting device further includes the step of forming a number of semiconductor light-emitting devices spaced apart along the substrate.

In an embodiment, the process for producing a semiconductor light-emitting device further includes the step of forming an electrode on at least a side of each semiconductor light-emitting device.

According to an embodiment of the present invention, a semiconductor light-emitting device is provided. The semiconductor light-emitting device includes a substrate including a substrate surface positioned along a substrate surface plane, a crystal layer having a crystal layer surface oriented along a crystal surface plane defined as a S-plane which diagonally intersects the substrate surface plane, and a layer of a first conductivity type, an active layer, and a layer of a second conductivity type each formed along the S-plane.

In an embodiment, the crystal layer is a wurtzite crystal structure.

In an embodiment, the crystal layer is composed of a nitride semiconductor material.

In an embodiment, the crystal layer is formed by selective growth on the substrate with a material layer capable of growth interposed therebetween.

In an embodiment, the material layer capable of growth is selectively removed during selective growth to form the crystal layer.

In an embodiment, the semiconductor light-emitting further includes a masking layer having an opening through which the crystal layer is selectively grown.

In an embodiment, the crystal layer is formed by selective growth such that the crystal layer extends laterally from the opening in the masking layer.

In an embodiment, the substrate surface plane comprises a C+ plane.

In an embodiment, current is injected into the active layer.

According to yet another embodiment of the present invention, a semiconductor light-emitting device is provided. The semiconductor light-emitting device includes a substrate including a substrate surface positioned along a substrate surface plane, a crystal layer in the shape of approximately hexagonal pyramid and having a face oriented along an S-plane that diagonally intersects the substrate surface plane, and a layer of a first conductivity type, an active layer, and a layer of a second conductivity type each formed along at least a portion of the approximately hexagonal pyramid.

In an embodiment, current is injected into the active layer such that a current density is lower near or at an apex of the approximately hexagonal pyramid than in the face of the approximately hexagonal pyramid.

According to a further embodiment of the present invention, a semiconductor light-emitting device is provided. The semiconductor light-emitting device includes a substrate including a substrate surface positioned along a substrate surface plane, a crystal layer in the shape of an approximately hexagonal prismoid, having a face oriented about an S-plane, and a top region oriented about a C-plane, and a layer of a first conductivity type, an active layer, and a layer of a second conductivity type each formed along at least a portion of the approximately hexagonal prismoid.

According to yet another embodiment of the present invention, an image display unit in provided. The image display unit includes a number of semiconductor light-emitting devices arranged so as to emit light in response to a signal, each of the semiconductor light-emitting devices having a substrate including a substrate surface positioned along a substrate surface plane, a crystal layer having a crystal surface oriented along a crystal surface plane defined as a S-plane which diagonally intersects the substrate surface plane, and a first conductive layer, an active layer, and a second conductive layer each formed along at least a portion of the crystal surface.

In an embodiment according to the present invention, a lighting system is provided. The lighting system includes a number of semiconductor light-emitting devices, each of the semiconductor light-emitting devices having a substrate including a substrate surface positioned along a substrate surface plane, a crystal layer having a crystal surface oriented along a crystal surface plane defined as a S-plane which diagonally intersects the substrate surface plane, and a first conductive layer, an active layer, and a second conductive layer each formed along at least a portion of the crystal surface.

In an embodiment, each of the semiconductor light-emitting devices in the lighting system are arranged so as to emit light in response to an identical signal.

In yet another embodiment according to the present invention, a process for producing a semiconductor light-emitting device is provided. The process includes the steps providing a substrate including a substrate surface oriented along a substrate surface plane, forming a masking layer on the substrate, wherein the masking layer includes an opening, forming a crystal layer by selective growth through the opening of the masking layer, wherein the crystal layer includes a crystal layer surface oriented along a crystal layer plane defined as a S-plane which diagonally intersects the substrate surface plane, and forming each of a first conductive layer, an active layer, and a second conductive layer along at least a portion of the crystal layer surface.

In an embodiment, the substrate surface plane is a C+ plane.

In an embodiment, the process for producing a semiconductor light-emitting device further includes the steps of forming a number of the semiconductor light-emitting devices on the substrate, and subsequently separating the semiconductor light-emitting devices.

In an embodiment, each separated semiconductor light-emitting device has at least one electrode formed on a side.

In a further embodiment according to the present invention, a semiconductor light-emitting device is provided. The semiconductor light-emitting device includes a substrate having a substrate surface positioned along a substrate surface plane, a crystal grown layer formed by selective growth having a crystal surface oriented along a crystal surface plane diagonally intersecting the substrate surface plane, an active layer which is formed along at least a portion of the crystal grown layer that emits light upon injection of an amount of current, and a reflecting region which is formed substantially parallel to the crystal surface plane and reflects at least a portion of the light emerging from the active layer.

In an embodiment, the active layer is formed from a compound semiconductor having a wurtzite crystal structure.

In an embodiment, the active layer is approximately parallel to the crystal surface plane.

In an embodiment, the active layer is approximately parallel to a S-plane.

In an embodiment, the active layer is approximately parallel to a plane having a plane orientation inclined at an angle ranging from about 5 to about 6 degrees with respect to at least one a S-plane and a (11 22) plane.

In an embodiment, the reflecting region includes at least two reflecting planes that intersect at an angle less than 180.degree..

In an embodiment, the active layer is formed from a nitride compound semiconductor.

In an embodiment, the active layer is formed from a gallium nitride compound semiconductor.

In an embodiment, the active layer contains In.

In an embodiment, the active layer is separated for each device.

In an embodiment, the semiconductor light-emitting device further includes an underlying layer formed on the substrate, wherein the selective growth of the crystal grown layer is derived from the underlying layer.

According to an embodiment of the present invention a process for producing a semiconductor light-emitting device is provided. The process includes the steps of providing a substrate including a substrate surface oriented along a substrate surface plane, selectively growing a crystal layer having a crystal surface oriented along a crystal surface plane diagonally intersecting the substrate surface plane, forming an active layer approximately parallel to the crystal surface plane, and forming a reflecting region substantially parallel to the crystal surface plane.

According to another embodiment of the present invention, a semiconductor light-emitting device is provided. The semiconductor light-emitting device includes a substrate having a substrate surface oriented along a substrate surface plane, a first grown layer having a first grown layer conductivity type formed on the substrate, a masking layer formed on the first grown layer, a second grown layer of a second grown layer conductivity type formed by selective growth through an opening in the masking layer having a crystal surface oriented along a crystal surface plane, a first cladding layer including a first cladding layer conductivity type formed along at least a portion of the crystal surface plane, an active layer, and a second cladding layer including a second cladding layer conductivity type, wherein at least one of the first cladding layer, the active layer, and the second cladding layer cover the masking layer surrounding the opening.

In an embodiment, the first grown layer conductivity type, the second grown layer conductivity type, and the first cladding layer conductivity type are all of a first conductivity type and the second cladding layer conductivity type is of a second conductivity type.

In an embodiment, the crystal surface plane of the second grown layer diagonally intersects the substrate surface plane.

In an embodiment, the first and second grown layers are composed of a wurtzite crystal structure.

In an embodiment, the second grown layer is composed of a nitride semiconductor.

In an embodiment, the substrate surface plane is a C-plane.

According to yet another embodiment of the present invention, a semiconductor light-emitting device is provided. The semiconductor light-emitting device includes a substrate, a first grown layer including a first grown layer conductivity type formed on the substrate, a masking layer formed on the first grown layer, a second grown layer including a second grown layer conductivity type formed by selective growth through an opening in the masking layer and having a crystal surface oriented along a crystal surface plane, a first cladding layer including a first cladding layer conductivity type formed along at least a portion of the crystal surface plane, an active layer, and a second cladding layer including a second cladding layer conductivity type, wherein the first cladding layer, the active layer, and the second cladding layer are formed as to substantially cover the second grown layer.

In an embodiment, the first grown layer conductivity type, the second grown layer conductivity type, and the first cladding layer conductivity type are all composed of a first conductivity type while the second cladding layer conductivity type is composed of a second conductivity type.

According to still another embodiment of the present invention, a semiconductor light-emitting device is provided. The semiconductor light-emitting device includes a substrate, a first grown layer of a first grown layer conductivity type formed on the substrate, a masking layer formed on the first grown layer, a second grown layer of a second grown layer conductivity type formed by selective growth through an opening in the masking layer and including a crystal surface oriented along a crystal surface plane, a first cladding layer of a first cladding layer conductivity type formed along at least a portion of the crystal surface plane, an active layer, and a second cladding layer of a second cladding layer conductivity type, wherein the first cladding layer, the active layer, and the second cladding layer are formed substantially parallel to the crystal surface plane such that an end region of at least one of the first cladding layer, the active layer, and the second cladding layer contacts the masking layer.

In an embodiment, the first grown layer conductivity type, the second grown layer conductivity type, and the first cladding layer conductivity type are all of a first conductivity type while the second cladding layer conductivity type is of a second conductivity type.

In an embodiment according to the present invention, an image display unit is provided. The image display unit includes a number of semiconductor light-emitting devices arranged so as to emit light in response to a signal, each of the semiconductor light-emitting devices having a substrate, a first grown layer of a first conductivity type formed on the substrate, a masking layer formed on the first grown layer, a second grown layer of the first conductivity type formed by selective growth through an opening in the masking layer and including a crystal surface oriented along a crystal surface plane, a first cladding layer of the first conductivity type formed along at least a portion of the crystal surface plane, an active layer, and a second cladding layer of a second conductivity type, wherein the first cladding layer, the active layer, and the second cladding layer are formed substantially parallel to the crystal surface plane such that an end region of at least one of the first cladding layer, the active layer, and the second cladding layer extends to the masking layer in proximity to the opening.

In another embodiment according to the present invention, a lighting system is provided. The lighting system includes a number of semiconductor light-emitting devices, each of the semiconductor light-emitting devices having a substrate, a first grown layer including a first conductivity type formed on the substrate, a masking layer formed on the first grown layer, a second grown layer including the first conductivity type formed by selective growth through an opening in the masking layer and including a crystal surface oriented along a crystal surface plane, a first cladding layer including the first conductivity type formed along at least a portion of the crystal surface plane, an active layer, and a second cladding layer of a second conductivity type, wherein the first cladding layer, the active layer, and the second cladding layer are formed substantially parallel to the crystal surface plane such that an end region of at least one of the first cladding layer, the active layer, and the second cladding layer extends to the masking layer in proximity to the opening.

In an embodiment, the lighting system is configured such that each of the semiconductor light-emitting devices are arranged so as to emit light in response to an identical signal.

According to yet another embodiment of the present invention, a process for producing a semiconductor light-emitting device is provided. The process includes the steps of providing a substrate including a substrate surface oriented along a substrate surface plane, forming a first grown layer on the substrate, forming a masking layer having an opening on the first grown layer, selectively growing a second grown layer through the opening in the masking layer, wherein the second grown layer includes a crystal surface oriented along a crystal surface plane, and forming a cladding layer of a first conductivity type, an active layer, and a cladding layer of a second conductivity type each substantially parallel to the crystal surface plane extending to the masking layer in proximity to the opening.

In an embodiment, the crystal surface plane of the second grown layer diagonally intersects the substrate surface plane.

According to a further embodiment of the present invention, a semiconductor light-emitting device is provided. The semiconductor light-emitting device includes a substrate having a substrate surface oriented along a substrate surface plane, and an active layer formed along at least a portion of a selectively grown crystal layer via a window region along the substrate surface plane such as to be disposed between a first conductive layer and a second conductive layer and oriented along an active layer plane that is not parallel to the substrate surface plane, and wherein an area of the active layer is larger than at least one of an area of the window region and a projected area of the crystal layer derived from projecting the crystal layer to the substrate surface plane in a normal direction.

In an embodiment, the active layer is composed of a compound semiconductor having a wurtzite crystal structure.

In an embodiment, the active layer is substantially parallel to a S-plane.

In an embodiment, the active layer is formed such that it extends laterally from the window region.

In an embodiment, the semiconductor light-emitting device further includes a first electrode connected to the first conductive layer, and a second electrode connected to the second conductive layer, wherein the first electrode and second electrode are capable of injecting current into the active layer.

In an embodiment, the active layer is a nitride compound semiconductor.

In an embodiment, the active layer is a gallium nitride compound semiconductor.

In an embodiment, the active layer contains In.

In an embodiment, the semiconductor light-emitting device further includes a number of semiconductor light-emitting devices selectively grown such that the active layer of each semiconductor light-emitting device is separated from the active layer of adjacent semiconductor light-emitting devices.

In an embodiment, the selective growth is derived from an underlying layer formed on the substrate.

According to an embodiment of the present invention, a semiconductor light-emitting device is provided. The semiconductor light-emitting device includes a substrate having a substrate surface oriented along a substrate surface plane, and an active layer formed by selective growth such as to be disposed between a first conductive layer and a second conductive layer and oriented along an active layer plane that is not parallel to the substrate surface plane, and wherein a portion of the active layer is directed away from the active layer plane towards the substrate.

According to yet an embodiment of the present invention, a semiconductor light-emitting device is provided. The semiconductor light-emitting device includes a substrate including a substrate surface oriented along a substrate surface plane, and an active layer formed along at least a portion of a selectively grown crystal layer such as to be disposed between a first conductive layer and a second conductive layer and oriented along an active layer plane that is not parallel to the substrate surface plane, and wherein an area of the active layer greater than or equal to a sum of a projected area of the crystal layer derived from projecting the crystal layer to the substrate in a normal direction and an area in which at least one of the conductive layers contacts a respective electrode formed on the substrate.

According to a further embodiment of the present invention, a process for producing a semiconductor light-emitting device is provided. The process includes the steps of forming an underlying layer on a substrate, forming a masking layer having a window region on the underlying layer, selectively growing a crystal grown layer through the window region, and forming a first conductive layer, an active layer, and a second conductive layer on a surface of the crystal grown layer, wherein the active layer includes a crystal surface with a surface area larger than a projected area derived from projecting the crystal surface toward the substrate in a normal direction.

According to another embodiment of the present invention, a process for producing a semiconductor light-emitting device is provided. The process includes the steps of providing a first substrate including a first substrate surface oriented along a first substrate surface plane, forming a crystal seed layer on the first substrate surface, forming a masking layer on the crystal seed layer, wherein the masking layer includes an opening, forming a crystal layer by selective growth of the crystal seed layer through the opening of the masking layer, wherein the crystal layer includes a crystal layer surface oriented along a crystal layer plane that diagonally intersects the first substrate surface plane, forming each of a first conductive layer, an active layer, and a second conductive layer along at least a portion of the crystal layer surface, embedding each of the first conductive layer, the active layer and the second conductive layer and the second conductive layer in a resin material layer formed on a second substrate, removing the second substrate by laser abrasion, separating the crystal seed layer and masking layer from a substrate region of the substrate, and forming an electrode on at least a portion of the substrate region.

In an embodiment, the crystal seed layer and the masking layer are separated by peeling off.

Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the Figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view showing a structure of a semiconductor light-emitting device.

FIG. 2 is a sectional view showing another structure of a semiconductor light-emitting device.

FIGS. 3A and 3B are diagrams showing the step of forming a mask in the production of the semiconductor light-emitting device in Example 1 of an embodiment of the present invention, wherein FIG. 3A is a sectional view and FIG. 3B is a perspective view.

FIGS. 4A and 4B are diagrams showing the step of forming a silicon-doped GaN layer in the production of the semiconductor light-emitting device in Example 1 of an embodiment of the present invention, wherein FIG. 4A is a sectional view and FIG. 4B is a perspective view.

FIGS. 5A and 5B are diagrams showing the step of forming a window for crystal growth in the production of the semiconductor light-emitting device in Example 1 of an embodiment of the present invention, wherein FIG. 5A is a sectional view and FIG. 5B is a perspective view.

FIGS. 6A and 6B are diagrams showing the step of forming an active layer etc. in the production of the semiconductor light-emitting device in Example 1 of an embodiment of the present invention, wherein FIG. 6A is a sectional view and FIG. 6B is a perspective view.

FIGS. 7A and 7B are diagrams showing the step of forming an electrode in the production of the semiconductor light-emitting device in Example 1 of an embodiment of the present invention, wherein FIG. 7A is a sectional view and FIG. 7B is a perspective view.

FIGS. 8A and 8B are diagrams showing the step of separating devices in the production of the semiconductor light-emitting device in Example 1 of an embodiment of the present invention, wherein FIG. 8A is a sectional view and FIG. 8B is a perspective view.

FIG. 9 is a sectional view showing the structure of the semiconductor light-emitting device in Example 1 of an embodiment of the present invention.

FIGS. 10A and 10B are diagrams showing the step of forming a mask in the production of the semiconductor light-emitting device in Example 2 of an embodiment of the present invention, wherein FIG. 10A is a sectional view and FIG. 10B is a perspective view.

FIGS. 11A and 11B are diagrams showing the step of selective removal in the production of the semiconductor light-emitting device in Example 2 of an embodiment of the present invention, wherein FIG. 11A is a sectional view and FIG. 11B is a perspective view.

FIGS. 12A and 12B are diagrams showing the step of forming a crystal layer in the production of the semiconductor light-emitting device in Example 2 of an embodiment of the present invention, wherein FIG. 12A is a sectional view and FIG. 12B is a perspective view.

FIGS. 13A and 13B are diagrams showing the step of forming an active layer in the production of the semiconductor light-emitting device in Example 2 of an embodiment of the present invention, wherein FIG. 13A is a sectional view and FIG. 13B is a perspective view.

FIGS. 14A and 14B are diagrams showing the step of forming an electrode in the production of the semiconductor light-emitting device in Example 2 of an embodiment of the present invention, wherein FIG. 14A is a sectional view and FIG. 14B is a perspective view.

FIGS. 15A and 15B are diagrams showing the step of separating devices in the production of the semiconductor light-emitting device in Example 2 of an embodiment of the present invention, wherein FIG. 15A is a sectional view and FIG. 15B is a perspective view.

FIG. 16 is a sectional view showing the semiconductor light-emitting device in Example 2 of an embodiment of the present invention.

FIGS. 17A and 17B are diagrams showing the step of separating devices in a modified way in the production of the semiconductor light-emitting device in Example 2 of an embodiment of the present invention, wherein FIG. 17A is a sectional view and FIG. 17B is a perspective view.

FIGS. 18A and 18B are diagrams showing the step of forming a mask in the production of the semiconductor light-emitting device in Example 3 of an embodiment of the present invention, wherein FIG. 18A is a sectional view and FIG. 18B is a perspective view.

FIGS. 19A and 19B are diagrams showing the step of forming a crystal layer in the production of the semiconductor light-emitting device in Example 3 of an embodiment of the present invention, wherein FIG. 19A is a sectional view and FIG. 19B is a perspective view.

FIGS. 20A and 20B are diagrams showing the step of forming an active layer in the production of the semiconductor light-emitting device in Example 3 of an embodiment of the present invention, wherein FIG. 20A is a sectional view and FIG. 20B is a perspective view.

FIGS. 21A and 21B are diagrams showing the step of forming an electrode in the production of the semiconductor light-emitting device in Example 3 of an embodiment of the present invention, wherein FIG. 21A is a sectional view and FIG. 21B is a perspective view.

FIGS. 22A and 22B are diagrams showing the step of separating devices in the production of the semiconductor light-emitting device in Example 3 of an embodiment of the present invention, wherein FIG. 22A is a sectional view and FIG. 22B is a perspective view.

FIG. 23 is a sectional view showing the semiconductor light-emitting device in Example 3 of an embodiment of the present invention.

FIGS. 24A and 24B are diagrams showing the step of forming a mask in the production of the semiconductor light-emitting device in Example 4 of an embodiment of the present invention, wherein FIG. 24A is a sectional view and FIG. 24B is a perspective view.

FIGS. 25A and 25B are diagrams showing the step of forming a crystal layer in the production of the semiconductor light-emitting device in Example 4 of an embodiment of the present invention, wherein FIG. 25A is a sectional view and FIG. 25B is a perspective view.

FIGS. 26A and 26B are diagrams showing the step of forming an active layer in the production of the semiconductor light-emitting device in Example 4 of an embodiment of the present invention, wherein FIG. 26A is a sectional view and FIG. 26B is a perspective view.

FIGS. 27A and 27B are diagrams showing the step of forming an electrode in the production of the semiconductor light-emitting device in Example 4 of an embodiment of the present invention, wherein FIG. 27A is a sectional view and FIG. 27B is a perspective view.

FIGS. 28A and 28B are diagrams showing the step of separating devices in the production of the semiconductor light-emitting device in Example 4 of an embodiment of the present invention, wherein FIG. 28A is a sectional view and FIG. 28B is a perspective view.

FIG. 29 is a sectional view showing the semiconductor light-emitting device in Example 4 of an embodiment of the present invention.

FIGS. 30A and 30B are diagrams showing the step of forming an electrode in the production of the semiconductor light-emitting device in Example 5 of an embodiment of the present invention, wherein FIG. 30A is a sectional view and FIG. 30B is a perspective view.

FIGS. 31A and 31B are diagrams showing the step of separating devices in the production of the semiconductor light-emitting device in Example 5 of an embodiment of the present invention, wherein FIG. 31A is a sectional view and FIG. 31B is a perspective view.

FIG. 32 is a sectional view showing the semiconductor light-emitting device in Example 5 of an embodiment of the present invention.

FIGS. 33A and 33B are diagrams showing the step of forming a p-electrode in the production of the semiconductor light-emitting device in Example 6 of an embodiment of the present invention, wherein FIG. 33A is a sectional view and FIG. 33B is a perspective view.

FIGS. 34A and 34B are diagrams showing the step of separating devices in the production of the semiconductor light-emitting device in Example 6 of an embodiment of the present invention, wherein FIG. 34A is a sectional view and FIG. 34B is a perspective view.

FIGS. 35A and 35B are diagrams showing the step of forming an n-electrode in the production of the semiconductor light-emitting device in Example 6 of an embodiment of the present invention, wherein FIG. 35A is a sectional view and FIG. 35B is a perspective view.

FIGS. 36A, 36B and 36C are diagrams showing the step of forming an n-electrode in a modified way according to an embodiment of the present invention, wherein FIG. 36A is a schematic sectional view snowing the laser abrasion step, FIG. 36B is a schematic sectional view showing the RIE step, and FIG. 36C is a schematic sectional view showing the step of forming an n-electrode.

FIG. 37 is a sectional view showing the semiconductor light-emitting device in Example 6 of an embodiment of the present invention.

FIG. 38 is a rear perspective view showing another structure of the semiconductor light-emitting device in Example 6 of an embodiment of the present invention.

FIGS. 39A and 39B are diagrams showing the step of forming a transparent electrode in the production of the modified semiconductor light-emitting device in Example 6 of an embodiment of the present invention, wherein FIG. 39A is a sectional view and FIG. 39B is a perspective view.

FIG. 40 is a sectional view showing the modified semiconductor light-emitting device in Example 6 of an embodiment of the present invention.

FIG. 41 is a perspective view showing the step of forming a mask in the production of the semiconductor light-emitting device in Example 7 of an embodiment of the present invention.

FIG. 42 is a perspective view showing the step of forming an active layer in the production of the semiconductor light-emitting device in Example 7 of an embodiment of the present invention.

FIG. 43 is a perspective view showing the step of forming an electrode in the production of the modified semiconductor light-emitting device in Example 7 of an embodiment of the present invention.

FIG. 44 is a sectional view showing the semiconductor light-emitting device in Example 7 of an embodiment of the present invention.

FIGS. 45A and 45B are diagrams showing the step of forming a mask in the production of the semiconductor light-emitting device in Example 8 of an embodiment of the present invention, wherein FIG. 45A is a sectional view and FIG. 45B is a perspective view.

FIGS. 46A and 46B are diagrams showing the step of forming a crystal layer in the production of the semiconductor light-emitting device in Example 8 of an embodiment of the present invention, wherein FIG. 46A is a sectional view and FIG. 46B is a perspective view.

FIGS. 47A and 47B are diagrams showing the step of forming an active layer in the production of the semiconductor light-emitting device in Example 8 of an embodiment of the present invention, wherein FIG. 47A is a sectional view and FIG. 47B is a perspective view.

FIGS. 48A and 48B are diagrams showing the step of forming an electrode in the production of the semiconductor light-emitting device in Example 8 of an embodiment of the present invention, wherein FIG. 48A is a sectional view and FIG. 48B is a perspective view.

FIGS. 49A and 49B are diagrams showing the step of separating devices in the production of the semiconductor light-emitting device in Example 8 of an embodiment of the present invention, wherein FIG. 49A is a sectional view and FIG. 49B is a perspective view.

FIG. 50 is a sectional view showing the semiconductor light-emitting device in Example 8 of an embodiment of the present invention.

FIGS. 51A and 51B are diagrams showing the step of forming an electrode in the production of the modified semiconductor light-emitting device in Example 8 of an embodiment of the present invention, wherein FIG. 51A is a sectional view and FIG. 51B is a perspective view.

FIG. 52 is a sectional view showing the modified semiconductor light-emitting device in Example 8 of an embodiment of the present invention.

FIGS. 53A and 53B are diagrams showing the step of forming an electrode in the production of the semiconductor light-emitting device in Example 9 of an embodiment of the present invention, wherein FIG. 53A is a sectional view and FIG. 53B is a perspective view.

FIG. 54 is a partial perspective view showing an apparatus that utilizes the semiconductor light-emitting device in Example 10 of an embodiment of the present invention.

FIG. 55 is a sectional view showing the structure of the semiconductor light-emitting device in Example 11 of an embodiment of the present invention.

FIG. 56 is a sectional view illustrating the area W1 of the window region of the semiconductor light-emitting device in Example 11 of an embodiment of the present invention.

FIG. 57 is a sectional view illustrating the projected area W2 of the crystal grown layer of the semiconductor light-emitting device in Example 11 of an embodiment of the present invention.

FIG. 58 is a perspective view showing the structure of the semiconductor light-emitting device in Example 12 of an embodiment of the present invention that is characterized by the crystal grown layer which is formed in a stripe pattern.

FIG. 59 is a perspective view showing the structure of the semiconductor light-emitting device in Example 13 of an embodiment of the present invention that is characterized by the crystal grown layer which is formed in a pattern of elongated quadrangular prismoids.

FIG. 60 is a perspective view showing the structure of the semiconductor light-emitting device in Example 14 of an embodiment of the present invention that is characterized by the crystal grown layer which is formed in a pattern of quadrangular prismoids.

FIG. 61 is a perspective view showing the structure of the semiconductor light-emitting device Example 15 of an embodiment of the present invention that is characterized by the crystal grown layer which is formed in a pattern of hexagonal pyramids.

FIG. 62 is a perspective view showing the structure of the semiconductor light-emitting device Example 16 of an embodiment of the present invention that is characterized by the crystal grown layer which is formed in a pattern of hexagonal prismoids.

FIG. 63 is a perspective view showing the step of forming an underlying layer for growth in the production of the semiconductor light-emitting device in Example 17 of an embodiment of the present invention.

FIG. 64 is a perspective view showing the step of forming window regions in the production of the semiconductor light-emitting device in Example 17 of an embodiment of the present invention.

FIG. 65 is a perspective view showing the step of forming a crystal grown layer in the production of the semiconductor light-emitting device in Example 17 of an embodiment of the present invention.

FIG. 66 is a perspective view showing the step of forming a layer of a second conductivity type in the production of the semiconductor light-emitting device in Example 17 of an embodiment of the present invention.

FIG. 67 is a perspective view showing the step of forming a contact region in the production of the semiconductor light-emitting device in Example 17 of an embodiment of the present invention.

FIG. 68 is a perspective view showing the step of forming an electrode in the production of the semiconductor light-emitting device in Example 17 of an embodiment of the present invention.

FIG. 69 is a sectional view showing the semiconductor light-emitting device in Example 18 of an embodiment of the present invention.

FIG. 70 is a sectional view showing the structure of the semiconductor light-emitting device in Example 19 of an embodiment of the present invention.

FIG. 71 is a sectional view showing a portion of the semiconductor light-emitting device in Example 19 of an embodiment of the present invention.

FIG. 72 is a perspective view showing the model of crystal grown layer that is used as the basis for calculations in production of the semiconductor light-emitting device in the Examples of an embodiment of the present invention.

FIG. 73 is a schematic diagram showing the model which is used for calculations of angle dependence in production of the semiconductor light-emitting device in Examples of an embodiment of the present invention.

FIG. 74 is a line graph showing the angle dependence on the light emergence efficiency which is obtained from the above-mentioned calculations in accordance with an embodiment of the present invention.

FIG. 75 is a schematic diagram showing the model which is used for calculations of height dependence in production of the semiconductor light-emitting device in Examples of an embodiment of the present invention.

FIG. 76 is a line graph showing the height dependence on the light emergence efficiency which is obtained from the above-mentioned calculations in accordance with an embodiment of the present