KR20100003331A - Light emitting device and method of manufacturing the same - Google Patents

Light emitting device and method of manufacturing the same Download PDF

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Publication number
KR20100003331A
KR20100003331A KR1020080060714A KR20080060714A KR20100003331A KR 20100003331 A KR20100003331 A KR 20100003331A KR 1020080060714 A KR1020080060714 A KR 1020080060714A KR 20080060714 A KR20080060714 A KR 20080060714A KR 20100003331 A KR20100003331 A KR 20100003331A
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South Korea
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layer
blocking layer
type semiconductor
blocking
semiconductor layer
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KR1020080060714A
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Korean (ko)
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김경훈
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서울옵토디바이스주식회사
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Priority to KR1020080060714A priority Critical patent/KR20100003331A/en
Publication of KR20100003331A publication Critical patent/KR20100003331A/en

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Abstract

The present invention relates to a light emitting device and a method of manufacturing the same.

In the light emitting device according to the present invention, a blocking layer between the active layer and the P-type semiconductor layer is formed by stacking a first blocking layer and a second blocking layer, and the second blocking layer gradually decreases the concentration of one element, for example, Al. To form.

Therefore, the lattice of the blocking layer is gradually reduced to form a high quality P-type semiconductor layer, and since the energy barrier can be lowered adjacent to the P-type semiconductor layer, holes can be easily injected from the P-type semiconductor layer into the active layer. Make sure

Description

Light emitting device and method of manufacturing the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device and a method of manufacturing the same, and more particularly, to a light emitting device capable of improving luminous efficiency by forming a blocking layer by laminating a first blocking layer and a second blocking.

In general, nitrides such as GaN, AlN, InN, and the like have excellent thermal stability and have a direct transition type energy band structure, which has recently attracted much attention as a material for photoelectric devices in the blue and ultraviolet regions. In particular, GaN can be used in high temperature high power devices because the energy bandgap is very large at 3.4 eV at room temperature. In addition, GaN can control energy bandgap from 1.9eV (InN) to 3.4eV (GaN), 6.2eV (AlN) in combination with materials such as InN and AlN, and thus has a wide wavelength range from visible light to ultraviolet light. Because of this, the application of the optical device is a very large material.

A light emitting device using a gallium nitride-based semiconductor generally has an N-type GaN layer, an active layer, and a P-type GaN layer formed on a substrate, and an N-type electrode and a P-type electrode connected to the N-type GaN layer and the P-type GaN layer, respectively. It consists of. When a predetermined current is applied to the N-type electrode and the P-type electrode of the light emitting device, electrons provided from the N-type GaN layer and holes provided from the P-type GaN layer are recombined in the active layer to generate short wavelength light corresponding to green or blue. Will be released. Here, a P-type blocking layer is formed between the active layer and the P-type GaN layer, which is formed of a nitride semiconductor layer containing Al such as P-type AlGaN having a larger energy band gap than the P-type GaN layer. Since gallium nitride-based semiconductors have higher mobility and concentration than electrons, electrons may overflow. At this time, since the P-type AlGaN layer has a larger energy band gap than the P-type GaN layer, electrons provided from the N-type GaN layer can be effectively prevented from overflowing without recombination in the active layer.

However, when the blocking layer is formed of the P-type AlGaN layer, it is difficult to form a high-quality P-type GaN layer because the lattice constant is different from that of the P-type GaN layer formed thereon. In addition, since the blocking layer serves as an energy barrier layer when holes are injected into the active layer, the hole injection effect is reduced. Therefore, the holes recombined in the active layer is reduced, thereby lowering the luminous efficiency of the light emitting device.

The present invention provides a light emitting device capable of forming a high quality P-type GaN layer and improving light emission efficiency and a method of manufacturing the same.

According to the present invention, a blocking layer is formed by stacking a first blocking layer and a second blocking layer, and the second blocking layer is formed such that the concentration of one element is gradually reduced, thereby forming a high quality P-type GaN layer, and emitting efficiency It provides a light emitting device and a method of manufacturing the same that can be improved.

The light emitting device according to the present invention comprises an N-type semiconductor layer formed on the substrate; An active layer formed on the N-type semiconductor layer; A blocking layer formed on the active layer and having a first blocking layer and a second blocking layer laminated; And a P-type semiconductor layer formed on the blocking layer, wherein the second blocking layer is formed by gradually decreasing the concentration of one element.

The first blocking layer and the second blocking layer are formed of layers having different components.

The first blocking layer and the second blocking layer are formed of an AlGaN layer and an AlInGaN layer or an AlInGaN layer and an AlGaN layer, and the second blocking layer is formed by gradually decreasing Al concentration.

A first undoped semiconductor layer formed between the substrate and the N-type semiconductor layer; And a second undoped semiconductor layer formed between the blocking layer and the P-type semiconductor layer.

According to another aspect of the present invention, there is provided a method of manufacturing a light emitting device, including forming an active layer after forming an N-type semiconductor layer on a substrate; Stacking a first blocking layer and a second blocking layer on the active layer to form a blocking layer; And forming a P-type semiconductor layer on the blocking layer, wherein the second blocking layer is formed such that the concentration of one element gradually decreases.

The first blocking layer and the second blocking layer are formed by stacking an AlGaN layer and an AlInGaN layer or an AlInGaN layer and an AlGaN layer, and the second blocking layer is formed by gradually decreasing the Al concentration.

According to the present invention, a blocking layer is formed by stacking a first blocking layer and a second blocking layer between an active layer and a P-type semiconductor layer, and the second blocking layer is formed such that the concentration of one element, for example, Al is gradually reduced. Form. In addition, the first blocking layer and the second blocking layer are formed by stacking layers having different components. The first blocking layer is formed of an AlGaN layer and the second blocking layer is formed of an AlInGaN layer, or the first blocking layer is formed of AlInGaN. The second blocking layer may be formed of an AlGaN layer.

As described above, when the blocking layer is formed, the lattice is gradually reduced to form a high-quality P-type semiconductor layer, and the energy barrier can be lowered adjacent to the P-type semiconductor layer, so that holes are easily formed from the P-type semiconductor layer. It can be injected into the active layer. Therefore, the luminous efficiency of a light emitting element can be improved.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention and to those skilled in the art. It is provided for complete information. In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity, and like reference numerals designate like elements. In addition, if a part such as a layer, film, area, etc. is expressed as “upper” or “on” another part, each part is different from each part as well as being “right up” or “directly above” another part. This includes the case where there is another part between parts.

1 is a cross-sectional view of a light emitting device according to an embodiment of the present invention. 2 and 3 are schematic diagrams showing an energy barrier of a blocking layer and its adjacent layer according to the present invention and the prior art.

Referring to FIG. 1, a light emitting device according to an exemplary embodiment may include a buffer layer 20, an N-type semiconductor layer 30, an active layer 40, a blocking layer 50, which are sequentially formed on a substrate 10, and The P-type semiconductor layer 60, the first electrode 70 formed on the N-type semiconductor layer 30, and the second electrode 80 formed on the P-type semiconductor layer 60 are included. Here, the blocking layer 50 is formed by stacking the first blocking layer 51 and the second blocking layer 52. The second blocking layer 52 is formed by gradually decreasing the concentration of one element. In addition, a predetermined region of the P-type semiconductor layer 60, the blocking layer 50, and the active layer 40 is etched in the first electrode 70 to expose a portion of the N-type semiconductor layer 30, and then the N-type semiconductor layer. 30 is formed on the upper portion, and the second electrode 80 is formed on the P-type semiconductor layer 60.

The substrate 10 refers to a conventional wafer for fabricating a light emitting device, using any one of Al 2 O 3 , SiC, ZnO, Si, GaAs, GaP, LiAl 2 O 3 , BN, AlN, and GaN.

The buffer layer 20 is formed to reduce lattice mismatch between the substrate 10 and the N-type semiconductor layer 30 during crystal growth of the N-type semiconductor layer 30, and is formed using GaN or AlN, which is a semiconductor material.

The N-type semiconductor layer 30 is a layer for injecting electrons into the active layer 40, it is preferable to use a GaN layer doped with N-type impurities, not limited to this, it is possible to have a material layer of various semiconductor properties. That is, a compound in which nitrides such as GaN, InN, AlN (Group III-V) and the like are mixed at a constant ratio may be used. In addition, the N-type semiconductor layer 30 may be formed of a multilayer film. Meanwhile, an N-type cladding layer (not shown) may be further formed on the N-type semiconductor layer 30, and the N-type cladding layer may be formed using GaN, AlGaN, or InGaN.

The active layer 40 has a predetermined band gap and is a region where quantum wells are made to recombine electrons and holes, and is preferably formed using InGaN. In this case, the emission wavelength generated by the combination of electrons and holes is changed according to the type of material constituting the active layer 40. Therefore, it is preferable to adjust the semiconductor material contained in the active layer 40 according to the target wavelength. In addition, the active layer 40 may be formed in a multilayer structure in which a quantum well layer and a barrier layer are alternately stacked.

The blocking layer 50 functions to prevent electrons provided from the N-type semiconductor layer 30 from overflowing without being recombined in the active layer 40. The blocking layer 50 according to the present invention is formed by stacking a first blocking layer 51 and a second blocking layer 52. In addition, in the blocking layer 50 according to the present invention, the first blocking layer 51 and the second blocking layer 52 are formed of materials different from each other. For example, the first blocking 51 may be formed of an AlInGaN layer, the second blocking layer 52 may be formed of an AlGaN layer, the first blocking layer 51 may be formed of an AlGaN layer, and the second blocking layer ( 52) may be formed of an AlInGaN layer. The second blocking layer 52 according to the present invention is formed such that the concentration of one element, for example, Al gradually decreases, so that Al is not added at the end. That is, when the second blocking layer 50 is formed of an AlGaN layer, after the first blocking layer 51 is formed of the AlInGaN layer, the inflow of the In source is stopped and the AlGaN layer is formed while the inflow of the Al source gradually decreases. The region in contact with the P-type semiconductor layer 60 is formed so that Al source does not flow. Thus, when the blocking layer 50 is formed as a double layer of the first blocking layer 51 and the second blocking layer 52 formed by decreasing the concentration of one element, the lattice gradually decreases, so that the high quality P-type semiconductor layer 60 is formed. Can be formed. In addition, since the energy barrier of the blocking layer 50 is lowered as shown in FIG. 2 than the conventional energy barrier shown in FIG. 3, holes from the P-type semiconductor layer 60 can be easily injected into the active layer 40. Make sure Therefore, the luminous efficiency of a light emitting element can be improved. On the other hand, the second blocking layer 52 is formed to a thickness of 10 to 1000 GPa, and the first blocking layer 51 and the second blocking layer 52 are P-type impurities, for example magnesium (Mg) or zinc (Zn). ) Is formed by doping.

The P-type semiconductor layer 60 is a layer for injecting holes into the active layer 40, it is preferable to use a GaN layer in which P-type impurities are implanted, and not limited to this, a material layer of various semiconductor properties is possible, for example InGaN can be used. In addition, the N-type semiconductor layer 30 and the P-type semiconductor layer 60 may be formed of a multilayer film.

The first electrode 70 and the second electrode 80 are formed using a metal material such as Cr, Au, Al, etc., and are formed in a single layer or multiple layers. Predetermined regions of the P-type semiconductor layer 60, the blocking layer 50, and the active layer 40 are etched in the first electrode 70 to expose a portion of the N-type semiconductor layer 30, and then the N-type semiconductor layer 30 ) Is formed on top.

Meanwhile, the above-described material layers may include metal organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), and molecular beam growth method. (Molecular Beam Epitaxy; MBE), hydride vapor phase growth (Hydride Vapor Phase Epitaxy; HVPE) and the like formed using a variety of deposition or growth methods.

In addition, the above embodiment has described a horizontal structure in which the first electrode 70 and the second electrode 80 are horizontally formed, but the first electrode 70 and the second electrode 80 are vertically formed, that is, The first electrode 70 may be formed in a vertical structure formed through the substrate 10.

Hereinafter, a method of manufacturing a light emitting device according to an exemplary embodiment of the present invention configured as described above will be described with reference to FIG. 4.

S10: A buffer layer 20 is formed on the substrate 10. The buffer layer 20 is formed by depositing a GaN layer by introducing ammonia (NH 3 ) as a nitrogen source and trimethylgallium (TMGa) as a gallium (Ga) source at a temperature of 450 to 550 ° C. Instead of the GaN layer, various materials such as an AlN layer, a GaInN layer, an AlGaInN layer, or a SiN layer may be formed as a buffer layer. The growth temperature and thickness may vary depending on the device or the growth system. Meanwhile, the surface of the substrate 10 may be nitrided after thermal cleaning the substrate 10 before the buffer layer 20 is formed on the substrate 10. The thermal cleaning process is carried out at a temperature of 950-1050 ° C. or slightly higher. After the thermal cleaning, a nitrogen source such as ammonia (NH 3 ) is introduced at a temperature of 700 to 1000 ° C. to nitride the surface of the substrate 10. Nitriding is a process for facilitating the formation of a nitride film and is selectively performed according to a system or growth conditions.

S20: An N-type semiconductor layer 30 is formed on the buffer layer 20, wherein the N-type semiconductor layer is formed of a GaN layer doped with N-type impurities. To this end, a GaN layer doped with silicon is formed by introducing TMGa as a gallium source, ammonia (NH 3 ) as a nitrogen source, and SiH 4 or SiH 6 as an N-type impurity at a temperature of about 900 to 1000 ° C. Meanwhile, in order to form InN, AlN, or the like instead of GaN as the N-type semiconductor layer 30, indium and aluminum sources may be introduced instead of gallium sources.

S30: The active layer 40 is formed on the N-type semiconductor layer 30. The active layer 40 has a single quantum well structure (SQW) or a double hetero structure (DH) or a multi quantum well structure formed of, for example, an InGaN layer. (MQW). To this end, an InGaN layer is formed by introducing trimethylindium (TMIn) as an indium source, TMGa as a gallium source, and ammonia (NH 3 ) as a nitrogen source at a temperature of 700 to 850 ° C.

S40: The blocking layer 50 is formed by stacking the first blocking layer 51 and the second blocking layer 52 on the active layer 40. The first blocking layer 51 may be formed of an AlInGaN layer, the second blocking layer 52 may be formed of an AlGaN layer, the first blocking layer 51 may be formed of an AlGaN layer, and the second blocking layer 52 may be formed of an AlGaN layer. It can be formed from an AlInGaN layer. Here, the case where the first blocking layer 51 and the second blocking layer 52 are formed of the AlGaN layer and the AlInGaN layer will be described. First, TMGa is used as a gallium source, trimethyaluminum (TMAl) as an aluminum source, and ammonia (NH 3 ) as a nitrogen source is introduced to form the first blocking layer 51 as an AlGaN layer. For example, it is formed by introducing a magnesium (Mg) source. Magnesium (Mg) sources are formed, for example, by introducing biscyclopentadienylmagnesium (Cp 2 Mg). The source is introduced to form a first blocking layer 51 to a predetermined thickness, and then a second blocking layer 52 is formed. In order to form the second blocking layer 52, TMIn is further introduced as an indium source while maintaining the inflow of gallium source, nitrogen source, and P-type impurities, and the aluminum source is gradually reduced. The aluminum source is introduced by setting the flow rate to be reduced at equal intervals according to the thickness of the second blocking layer 52 that is set in advance. On the other hand, the blocking layer 50 may be formed by stacking the first blocking layer 51 and the second blocking layer 52 at a temperature of 900 ~ 1100 ℃, the blocking layer 50 at a temperature of less than 900 ℃ If formed, the crystallinity of the blocking layer 50 is reduced, and the active layer 40 may be damaged when the blocking layer 50 is formed at a temperature of 1100 ° C. or higher.

S50: After the blocking layer 50 is formed, the aluminum source and the indium source are stopped while the temperature is maintained at 900 to 1100 ° C., and the gallium source, the nitrogen source, and the magnesium source are introduced to the P-type semiconductor layer (60). ) To form a P-type GaN layer.

Subsequently, predetermined regions of the P-type semiconductor layer 60, the blocking layer 50, and the active layer 40 are etched to expose the predetermined region of the N-type semiconductor layer 30, and the upper portions of the N-type semiconductor layer 30 are formed on the N-type semiconductor layer 30. The second electrode 80 is formed on the first electrode 70 and the P-type semiconductor layer 60. Of course, the first electrode 70 may be formed to etch a predetermined region behind the substrate 10 to expose the N-type semiconductor layer 30 and to be connected to the N-type semiconductor layer 30.

In addition, triethylgallium (TEGa) may be used as the source of gallium in addition to trimethylgallium (TMGa), and triethylaluminum (TEAl) and trimethyl in addition to trimethyaluminum (TMAl) as the aluminum source. Trimethylaminealuminum (TMAAl) or dimethylethylaminealuminum (DMEAAl) may be used. In addition, as the nitrogen source, monomethylhydrazine (MMHy) and dimethylhydrazine (DMHy) may be used in addition to ammonia (NH 3 ), and triethylindium (TEIn) may be used as the indium source.

5 is a cross-sectional view of a light emitting device according to another embodiment of the present invention.

Referring to FIG. 5, a light emitting device according to another exemplary embodiment of the present invention may include a buffer layer 20, a first undoped semiconductor layer 25, an N-type semiconductor layer 30, and an active layer that are sequentially formed on the substrate 10. 40, the blocking layer 50, the second undoped semiconductor layer 55, the P-type semiconductor layer 60 and the contact layer 65, and the first electrode 70 formed on the N-type semiconductor layer 30. ) And a second electrode 80 formed on the P-type semiconductor layer 60. Here, the blocking layer 50 is formed by stacking the first blocking layer 51 and the second blocking layer 52. In the light emitting device according to another embodiment of the present invention, the first and second undoped semiconductor layers 25 and 55 and the contact layer 65 are further formed as compared with the light emitting device according to the embodiment.

Substrate 10, buffer layer 20, first type semiconductor layer 30, active layer 40, blocking layer 50, second type semiconductor layer 60, first electrode 70 and second electrode ( 80 is the same as the light emitting device according to an embodiment of the present invention, so a detailed description thereof will be omitted.

The first undoped semiconductor layer 25 is preferably formed of an undoped GaN layer, and since the first undoped semiconductor layer 25 is formed, the N-type semiconductor layer 30 thereon is higher in quality and faster. It can form using a material.

The second undoped semiconductor layer 55 is preferably formed of an undoped GaN layer and is formed during the growth stop period of forming the P-type semiconductor layer 60 in the blocking layer 50.

The contact layer 65 is preferably formed of a GaN layer doped with P-type impurities at a higher concentration than the P-type semiconductor layer 60. The contact layer 65 is formed to improve the adhesive property of the second electrode 80.

Meanwhile, a transparent electrode (not shown) may be formed on the contact layer 65, or the transparent electrode may be formed on the P-type semiconductor layer 60 without forming the contact layer 65. The transparent electrode is formed using an ITO film, a Ni / Au film, or the like, and is formed by sputtering, E-Beam Evaporation, Chemical Vapor Deposition (CVD), and ion plating (ion-plating). By using a method or the like. For example, a method of forming an ITO film using sputtering includes reactive sputtering using an In—Sn alloy target, sputtering using an In 2 O 3 —Sn 2 O 2 oxide target, and the like.

Although the technical spirit of the present invention has been described in detail according to the above embodiment, it should be noted that the above embodiment is for the purpose of description and not for the purpose of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

1 is a cross-sectional view of a light emitting device according to an embodiment of the present invention.

2 is a schematic view showing an energy barrier of a light emitting device according to an embodiment of the present invention.

3 is a schematic view showing an energy barrier of a conventional light emitting device.

4 is a flowchart illustrating a method of manufacturing a light emitting device according to an embodiment of the present invention.

5 is a cross-sectional view of a light emitting device according to another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10 substrate 20 buffer layer

30: N-type semiconductor layer 40: active layer

50: blocking layer 51: first blocking layer

52: second blocking layer 60: p-type semiconductor layer

70: first electrode 80: second electrode

Claims (7)

An N-type semiconductor layer formed on the substrate; An active layer formed on the N-type semiconductor layer; A blocking layer formed on the active layer and having a first blocking layer and a second blocking layer laminated; And P-type semiconductor layer formed on the blocking layer, The second blocking layer is a light emitting device formed by gradually decreasing the concentration of one element. The light emitting device of claim 1, wherein the first blocking layer and the second blocking layer are formed of layers having different components. The light emitting device of claim 2, wherein the first blocking layer and the second blocking layer are formed of an AlGaN layer and an AlInGaN layer, or an AlInGaN layer and an AlGaN layer. The light emitting device of claim 3, wherein the second blocking layer is formed by gradually decreasing Al concentration. The semiconductor device of claim 1, further comprising: a first undoped semiconductor layer formed between the substrate and the N-type semiconductor layer; And And a second undoped semiconductor layer formed between the blocking layer and the p-type semiconductor layer. Forming an N-type semiconductor layer on the substrate and then forming an active layer; Stacking a first blocking layer and a second blocking layer on the active layer to form a blocking layer; And Forming a P-type semiconductor layer on the blocking layer; The second blocking layer is a method of manufacturing a light emitting device to form so that the concentration of one element gradually decreases. 7. The light emitting device of claim 6, wherein the first blocking layer and the second blocking layer are formed by stacking an AlGaN layer and an AlInGaN layer or an AlInGaN layer and an AlGaN layer, and the second blocking layer is formed by gradually reducing the Al concentration. Method of manufacturing the device.
KR1020080060714A 2008-06-26 2008-06-26 Light emitting device and method of manufacturing the same KR20100003331A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20130015112A (en) 2011-08-02 2013-02-13 서울옵토디바이스주식회사 Light emitting diode and method of fabricating the same
KR20140096846A (en) * 2013-01-29 2014-08-06 엘지이노텍 주식회사 Light emitting device
WO2017049053A1 (en) * 2015-09-17 2017-03-23 Crystal Is, Inc. Ultraviolet light-emitting devices incorporating two-dimensional hole gases

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20130015112A (en) 2011-08-02 2013-02-13 서울옵토디바이스주식회사 Light emitting diode and method of fabricating the same
KR20140096846A (en) * 2013-01-29 2014-08-06 엘지이노텍 주식회사 Light emitting device
WO2017049053A1 (en) * 2015-09-17 2017-03-23 Crystal Is, Inc. Ultraviolet light-emitting devices incorporating two-dimensional hole gases
US9680057B2 (en) 2015-09-17 2017-06-13 Crystal Is, Inc. Ultraviolet light-emitting devices incorporating two-dimensional hole gases
US9806227B2 (en) 2015-09-17 2017-10-31 Crystal Is, Inc. Ultraviolet light-emitting devices incorporating graded layers and compositional offsets
US10211368B2 (en) 2015-09-17 2019-02-19 Crystal Is, Inc. Ultraviolet light-emitting devices incorporating graded layers and compositional offsets
US10211369B2 (en) 2015-09-17 2019-02-19 Crystal Is, Inc. Ultraviolet light-emitting devices incorporating two-dimensional hole gases
US10700237B2 (en) 2015-09-17 2020-06-30 Crystal Is, Inc. Ultraviolet light-emitting devices incorporating graded layers and compositional offsets

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