KR101349444B1

KR101349444B1 - Semiconductor light-emitting device and manufacturing method thereof

Info

Publication number: KR101349444B1
Application number: KR1020070060934A
Authority: KR
Inventors: 김경준
Original assignee: 엘지이노텍 주식회사
Priority date: 2007-06-21
Filing date: 2007-06-21
Publication date: 2014-01-15
Also published as: KR20090002195A

Abstract

The present invention relates to a nitride semiconductor light emitting device and a manufacturing method thereof.

A nitride semiconductor light emitting device according to the present invention includes: a substrate; An n-type contact layer formed on the substrate; An active layer formed on the n-type contact layer; A first p-type clad layer formed on the active layer; An InGaN quantum dot layer formed on the first p-type cladding layer; A GaN cap layer on the InGaN quantum dot layer; A second p-type cladding layer formed on the GaN cap layer; And a p-type contact layer formed on the second p-type cladding layer.

A nitride semiconductor light emitting device, a quantum dot,

Description

TECHNICAL FIELD The present invention relates to a nitride semiconductor light emitting device,

1 is a sectional view of a conventional nitride semiconductor light emitting device.

2 is a cross-sectional view illustrating a nitride semiconductor light emitting device according to an embodiment of the present invention.

Description of the Related Art

100: nitride semiconductor light emitting device 111: substrate

113: buffer layer 115: undoped-GaN layer

117: n-type contact layer 119: n-type cladding layer

121: active layer 123: first p-type cladding layer

125 InGaN quantum dot layer 127 GaN cap layer

129: second p-type cladding layer 131: p-type contact layer

In general, GaN, Aln, and InN among Group III-V compound semiconductors have a wide bandgap ranging from 0.7 to 6.2 eV, and thus are attracting attention in that various colors can be obtained through semiconductors.

1 is a cross-sectional view of a conventional nitride semiconductor light emitting device.

1, the nitride semiconductor light emitting device 10 includes a buffer layer 13 formed on a sapphire substrate 11, an undoped GaN layer 15 and an n-GaN layer (not shown) 17 are formed in this order. An active layer 19 formed of a single or multiple quantum well structure on the n-GaN layer and emitting light, and a p-GaN layer 21 are sequentially stacked on the active layer 19. The n-GaN layer 17 is mainly doped with Si and the p-GaN layer 21 is mainly doped with Mg.

A part of the p-GaN layer 21 is etched to a portion of the n-GaN layer 17 to expose the n-GaN layer 17 to the outside and form an n-type electrode in the n-GaN layer 17 And a p-type electrode is formed on the p-GaN layer 21.

Each layer may be formed by various methods such as electron beam evaporation, physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma laser deposition (PLD), dual-type thermal evaporator sputtering, MOCVD chemical vapor deposition) or the like.

This nitride semiconductor light emitting device has a principle that photons are generated by recombination of electrons and holes in the active layer 19 between P / N junctions.

Light generated in the active layer 19 is emitted in all directions. Research is underway to improve electrical characteristics and external quantum efficiency caused by contact resistance on the surface of each nitride layer when light is emitted.

The present invention provides a nitride semiconductor light emitting device and a method of manufacturing the same.

The present invention provides a nitride semiconductor light emitting device and a method for manufacturing the same, which are intended to improve luminous efficiency by forming roughness by forming a quantum dot layer using indium and a cap layer protecting the same on the active layer.

A nitride semiconductor light emitting device according to the present invention, a substrate; An n-type contact layer formed on the substrate; An active layer formed on the n-type contact layer; A first p-type clad layer formed on the active layer; An InGaN quantum dot layer formed on the first p-type cladding layer; A GaN cap layer on the InGaN quantum dot layer; A second p-type cladding layer formed on the GaN cap layer; And a p-type contact layer formed on the second p-type cladding layer.

A method of manufacturing a nitride semiconductor light emitting device according to an embodiment of the present invention includes: forming an n-type contact layer on a substrate; Forming an active layer on the n-type contact layer; Forming a first p-type cladding layer on the active layer; Forming an InGaN quantum dot layer on the first p-type cladding layer; Forming a GaN cap layer on the InGaN quantum dot layer; Forming a second p-type cladding layer on the GaN cap layer; And forming a p-type contact layer on the second p-type cladding layer.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

2, the nitride semiconductor light emitting device 100 includes a substrate 111, a buffer layer 113, an undoped GaN layer 115, an n-type contact layer 117, an n-type clad layer 119, and an active layer ( 121), a first p-type cladding layer 123, an InGaN quantum dot layer 125, a GaN cap layer 127, a second p-type cladding layer 129, and a p-type contact layer 131.

The substrate 111 is formed of sapphire, GaN, SiC, ZnC, GaAs, or Si, and a buffer layer 113 is formed on the substrate. The buffer layer 113 is to reduce the difference in lattice constant between the substrate 111 and the GaN layer 117, and GaN, AlN, AlGaN, InGaN and Al _X Ga _Y ln _1-XY N (O≤X, O≤ Y, X + Y ≦ 1) and the like may be used. An undoped GaN layer 115 is grown on the buffer layer without dopant doping.

An n-type contact layer 117 is formed on the undoped GaN layer 115. The n-type contact layer 117 is an n-GaN layer and is doped with a dopant such as silicon (Si) do. As the n-type dopant, Si, Ge, Se, Te, or the like may be added.

The active layer 121 having a single quantum well or multiple quantum well (MQW) structure is formed on the n-type contact layer 117. The active layer 121 may be formed of InGaN / GaN MQW or AlGaN / GaN MQW. Alternatively, an n-type cladding layer 119 may be formed on the n-type contact layer 117, and an active layer 121 may be formed thereon. Here, the n-type cladding layer is un-doped or n-type doped Al _X Ga _Y In ₁ _-X- _Y N / Al _X Ga _Y In ₁ _-X- _Y N (0≤X, 0≤Y, X + A pair of Y≤1) may be formed of one or more clad layers.

After the active layer 121 is formed, one or more p-type cladding layers 123 and 129 may be formed on the active layer 121, and the p-type contact layer 131 is formed on the last p-type cladding layer 129.

The one or more p-type cladding layers 123 and 129 may be grown as p-AlGaN layers, and at least one stack between the first p-type cladding layer 123 and the p-type contact layer 131 to create roughness. Structures may be added.

To this end, a first p-type cladding layer 123 is formed on the active layer 121, an InGaN quantum dot layer 125 is formed on the p-type cladding layer 123, and on the InGaN quantum dot layer 125. A GaN cap layer 127 may be formed to protect a quantum dot (QD), and a second p-type cladding layer 129 may be formed on the GaN cap layer 127, and then a p-type contact layer 131 may be formed. have.

When the InGaN quantum dot layer 125 is grown, an In-rich InGaN QD is formed by inserting an amount of In about 10 to 500 times more than the amount of Ga. At this time, in order for Incorporation of In to be well, the formation temperature of the InGaN quantum dot layer 125 is 600-800 ° C and the growth time is about 3-30 seconds. Here, as the growth time increases, the size and height of the quantum dots QD increase. The size of such a quantum dot has a diameter (Diameater) of 50 to 200 nm and a height of 1 to 20 nm.

Here, the InGaN quantum dot layer 125 has a large lattice mismatch with the p-type AlGaN layer 123 at the bottom, thereby promoting three-dimensional growth of the quantum dots.

After the InGaN quantum dot layer 125 is formed, a GaN capping layer 127 is formed. The GaN capping layer 127 is a layer for maintaining the quantum dot shape as it is, and is N-rich or Ga-rich GaN. It is formed of a cap layer. Here, N-rich or Ga-rich typically represents an amount larger than that used in other existing layers. In addition, the GaN cap layer 127 is grown for 3 to 30 seconds at a growth temperature of 600 ~ 800 ℃.

When the InGaN quantum dot layer 125 and the GaN cap layer 127 are paired, they may be formed as 1 to 10 pairs. In addition, an n-type or p-type dopant may be doped into at least one of the InGaN quantum dot layer 125 and the GaN cap layer 127.

A second p-type cladding layer 129 is formed on the GaN cap layer 127, and the second p-type cladding layer 129 may be formed of a p-AlGaN layer.

Accordingly, the p-type contact layer 131 is formed on the second p-type cladding layer 129. In this case, roughness of the surface of the second p-type cladding layer 129 and the p-type contact layer 131 is roughened by the lower InGaN quantum dot layer 125 and the GaN cap layer 127.

The p-type contact layer 131 is formed by adding Mg, Zn, Ca, Sr, Ba, or the like to GaN as a p-type dopant.

This roughness serves to reduce the contact resistance, thereby improving the electrical properties and the external quantum efficiency. In the roughness at this time, the density of the projections is made from 1 × 10 ⁸ / cm ² to 5 × 10 ¹⁰ / cm ² .

According to the present invention, carrier confinement is increased due to quantum dots uniformly formed in a small size on the active layer, thereby increasing supply of carriers to the active layer, thereby increasing efficiency of internal light emission.

In addition, a transparent electrode layer (not shown) may be formed on the p-type contact layer 131, and the transparent electrode layer may be selected from materials of ITO, ZnO, IrOx, RuOx, and NiO.

Although the present invention has been described above with reference to the embodiments, these are merely examples and are not intended to limit the present invention. Those skilled in the art to which the present invention pertains should be provided within the scope not departing from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not possible.

For example, each component specifically shown in the embodiments of the present invention can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

According to the nitride semiconductor light emitting device according to the present invention and a method of manufacturing the same, by forming a quantum dot using indium and a cap layer thereof on the p-type cladding layer on the active layer, the roughness is made to improve the internal light emission efficiency, the contact resistance is reduced Electrical characteristics can be improved.

Claims

Board;

An n-type contact layer formed on the substrate;

An active layer formed on the n-type contact layer;

A first p-type clad layer formed on the active layer;

An InGaN quantum dot layer formed on the first p-type cladding layer;

A GaN cap layer formed on the InGaN quantum dot layer;

A second p-type cladding layer formed on the GaN cap layer;

And a p-type contact layer formed on the second p-type cladding layer.

The method according to claim 1,

The InGaN quantum dot layer is a nitride semiconductor light emitting device comprising an In-rich InGaN quantum dot in the amount of In more than the amount of Ga.

The method according to claim 1,

The surface of the second p-type cladding layer or the p-type contact layer has a roughness, the roughness has a density of the projection of 1 × 10 ⁸ / cm ² ~ 5 × 10 ¹⁰ / cm ² .

4. The method according to any one of claims 1 to 3,

A quantum dot of the InGaN quantum dot layer is a nitride semiconductor light emitting device having a diameter of 50 ~ 200nm, a height of 1 ~ 20nm.

4. The method according to any one of claims 1 to 3,

The GaN cap layer is a nitride semiconductor light emitting device comprising a GaN layer formed of N-rich or Ga-rich.

4. The method according to any one of claims 1 to 3,

Wherein the pair of the InGaN quantum dot layer and the GaN cap layer are formed in a pair of 1 to 10 pairs.

4. The method according to any one of claims 1 to 3,

At least one of the InGaN quantum dot layer and the GaN cap layer is doped with an n-type or p-type dopant.

4. The method according to any one of claims 1 to 3,

A buffer layer formed on the substrate between the substrate and the n-type contact layer; And an undoped GaN layer on the buffer layer.

9. The method of claim 8,

A nitride semiconductor light emitting device comprising an n-type cladding layer formed between the n-type contact layer and the active layer.

The nitride semiconductor light emitting device according to any one of claims 1 to 3, wherein at least one of the first and second p-type clad layers is formed of an AlGaN layer.

Forming an n-type contact layer on the substrate;

Forming an active layer on the n-type contact layer;

Forming a first p-type cladding layer on the active layer;

Forming an InGaN quantum dot layer on the first p-type cladding layer;

Forming a GaN cap layer on the InGaN quantum dot layer;

Forming a second p-type cladding layer on the GaN cap layer;

And forming a p-type contact layer on the second p-type cladding layer.

12. The method of claim 11,

Wherein the InGaN quantum dot layer is doped with In in an amount of 10 to 500 times the amount of Ga.

The method of claim 11 or 12,

The GaN cap layer is formed of N-rich or Ga-rich nitride semiconductor light emitting device manufacturing method.

The method of claim 11 or 12,

A method of manufacturing a nitride semiconductor light emitting device comprising 1 to 10 pairs of the InGaN quantum dot layer and the GaN cap layer as a pair.

The method of claim 11 or 12,

Forming a buffer layer on a substrate below the n-type contact layer, and forming an undoped GaN layer on the buffer layer.

The method of claim 11 or 12,

The n-type cladding layer is formed between the n-type contact layer and the active layer.