KR101455798B1 - Nitride light emitting device having improved light emitting efficiency using plasmons - Google Patents

Abstract

The present invention relates to a light emitting device having improved light emitting efficiency and a method of manufacturing the same, and a light emitting device of the present invention includes a p-type reflective contact layer 110; A p-type nitride layer 120 formed on the p-type reflective contact layer 110; An active layer 130 formed on the p-type nitride layer 120; An n-type nitride layer 140 formed on the active layer 130; Type nitride layer 120 and the active layer 130 to form an n-type nitride layer 151. The n-type nitride layer 152 is formed of a metal nano- (150) having an n-type electrode (153) provided to be in contact with the n-type nitride semiconductor layer (140), thereby increasing the luminous efficiency due to a local plasmon resonance effect in the vertical nitride light emitting device And the light emitting efficiency can be further improved by excluding the electrode arrangement structure which is disadvantageous for the light extraction efficiency on the light emitting surface.

Description

TECHNICAL FIELD [0001] The present invention relates to a light emitting device having improved luminous efficiency due to plasmon and a method of manufacturing the same.

The present invention relates to a light emitting device and a method of fabricating the same, and more particularly, to a method of manufacturing a light emitting device and a method of manufacturing the same, which are capable of achieving local plasmon resonance without loss of a light emitting area through n-type electrodes of a trench structure and metal nano- Efficiency light emitting device and a method of manufacturing the same.

Materials that are currently of interest as high-brightness light emitting devices include, but are not limited to, semiconductors of III-V semiconductors, in particular Al, Al, Ga, Quaternary alloy.

On the other hand, the nitride-based light emitting device shows a low light extraction efficiency due to the refractive index of the material, and the difference between the refractive index of GaN (about 2.4) and the refractive index of air (about 1.0) Part is totally reflected and is not emitted to the outside, is absorbed in the device and is destroyed, and the luminous efficiency is low.

In order to improve the low luminous efficiency of such a nitride-based light emitting device, there is a proposal to improve the luminous efficiency of the semiconductor light emitting device using surface plasmon resonance.

For example, Japanese Unexamined Patent Application Publication No. 10-2011-0103229 (published on September 20, 2011) (hereinafter referred to as "Prior Art Document 1") discloses a semiconductor light emitting device comprising a first conductive semiconductor layer, A nano rod, an active layer formed so as to cover the nano-rod, and a plasmon generator which is formed to cover the active layer and which has a metal material and causes a surface plasmon of a metal material to resonate with light emitted from the active layer. A light emitting element is proposed.

As another example, Japanese Patent Application Laid-Open No. 10-1011108 (registered on January 19, 2011) (hereinafter referred to as "Prior Art 2") discloses a light emitting device using selective surface plasmon coupling and a method for the same, The present inventors have proposed a light emitting device and a method of manufacturing the same that improve the luminous efficiency by further improving the resonance or coupling effect of light with surface plasmons by selectively forming a metal nanoparticle layer only in the concave region adjacent to the active layer among the concave- have.

However, in the prior arts 1 and 2, the vertical light emitting device has a structure in which the electrode covers a part of the upper part of the light emitting device, and absorption of light by the electrode occurs, resulting in a relatively decreased light emitting area, .

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art, and it is an object of the present invention to provide a metal nanoparticle layer formed on an n-type electrode portion formed on a trench and a metal nanoparticle layer, In order to enhance the luminous efficiency due to the local plasmon resonance effect between the metal nanoparticle layer and the active layer, particularly, it is possible to eliminate the electrode arrangement structure which is disadvantageous for the light extraction efficiency on the light emitting surface of the vertical type light emitting device, And a method of manufacturing the same.

According to an aspect of the present invention, there is provided a light emitting device comprising: a p-type reflective contact layer; A p-type nitride layer formed on the p-type reflective contact layer; An active layer formed on the p-type nitride layer; An n-type nitride layer formed on the active layer; An n-type electrode provided on the p-type reflective contact layer, the p-type nitride layer, and the active layer, the n-type electrode being formed to be insulated by an insulating layer including metal nano- Lt; / RTI >

Preferably, in the light emitting device of the present invention, the p-type nitride layer includes a second plasmon generator having an insulating material including metal nanoparticles, and the metal nanoparticles of the second plasmon generator may be distributed within 100 nm from the active layer And the second plasmon generator may be positioned through the active layer.

Preferably, in the light emitting device of the present invention, the size of the metal nanoparticles is 1 nm to 100 nm.

Next, a method of manufacturing a light emitting device according to the present invention includes a first step of sequentially laminating an n-type nitride layer, an active layer, and a p-type nitride layer on a growth substrate; A second step of penetrating the p-type nitride layer and the active layer to form a trench structure to a predetermined depth of the n-type nitride layer; A third step of forming a p-type reflective contact layer on the surface of the p-type nitride layer; A fourth step of forming an insulating layer on the surface of the p-type reflective contact layer including the surface of the trench structure so that metal nanoparticles are insulated and distributed in the trench structure; A fifth step of forming an n-type electrode in the trench structure of the fourth step; A sixth step of forming a conductive layer on the surface of the n-type electrode and the insulating layer and bonding the substrate; And a seventh step of separating the growth substrate bonded to the n-type nitride layer.

The method may further include forming a p-type electrode in the p-type reflective contact layer after the sidewall etching after the seventh step. In the seventh step, And forming a roughness on the surface of the n-type nitride layer having been separated.

In the semiconductor light emitting device according to the present invention, a metal nanoparticle layer is formed around an n-type electrode formed on a trench, and a metal nanoparticle layer is interposed on an upper portion or a lower portion of an active layer other than the n-type electrode. It is possible to increase the luminous efficiency due to the local plasmon resonance effect in the vertical type nitride light emitting device and to improve the light emission efficiency by the scattering, diffraction and refractive index difference between the light generated in the active layer and the plasmon generating part, The light extraction efficiency can be increased by changing the path. Further, the light emitting efficiency can be further improved by eliminating the electrode arrangement structure which is disadvantageous for the light extraction efficiency on the light emitting surface.

Also, the method of manufacturing a semiconductor light emitting device according to the present invention can provide an efficient manufacturing process of a light emitting device in which an n-type electrode can be formed in a plasmon generating portion having a trench structure in a vertical type nitride light emitting device.

1 is a cross-sectional view of a light emitting device according to a first embodiment of the present invention.
2 is a cross-sectional view illustrating a light emitting device according to a second embodiment of the present invention.
3 is a cross-sectional view of a light emitting device according to a third embodiment of the present invention.
4 is a view schematically showing a manufacturing process of a light emitting device according to the present invention.

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

1 is a cross-sectional view of a light emitting device according to a first embodiment of the present invention. In the light emitting device 100 of the present invention, a P-type reflective contact layer 110, a p- The active layer 130 and the n-type nitride layer 140 are stacked on one another and include a trench-type plasmon generator 150.

The substrate 101 is provided as a base layer in which a light emitting device is provided, and a GaN based substrate, SiC or SI substrate, ZnO, sapphire substrate, or the like can be used.

A conductive layer 102 and an insulating layer 103 may be formed on the substrate 101. The conductive layer 102 is contacted with the n-type electrode 153 constituting the plasmon generating part 150, .

The p-type reflective contact layer 110 reflects light generated by the active layer 130 and amplified by the plasmon resonance effect to improve light output, and a p-type electrode 111 is formed in a part of the upper surface .

As the p-type reflective contact layer 110, a highly reflective metal material may be used. For example, a sliver or aluminum (Al) may be used to provide a relatively low light absorption and a low contact resistance, A multi-layer structure combining a metal or a semi-metal may be used for low light absorption and low contact resistance.

The p-type nitride layer 120 and the n-type nitride layer 140 are p-type and n-type nitride semiconductor layers doped with a p-type impurity and an n-type impurity, respectively. Examples of the nitride semiconductor include aluminum (Al) GaN, AlN, InN, AlGaN, AlInN, GaInN, AlInGaN, and the like, which are exemplified by GaN, GaN, In, and N .

The active layer 130 is stacked between the p-type nitride layer 120 and the n-type nitride layer 140 and is formed in a single or multi-layer quantum well structure formed of a nitride semiconductor containing indium and gallium And recombination of electrons and holes is made to emit light.

The plasmon generator 150 includes a trench structure in which an upper end portion of the p-type reflective contact layer 110, the p-type nitride layer 120, and the active layer 130 is positioned within the n-type nitride layer 140 The n-type electrode 153 is in contact with the n-type nitride layer 140 at the top end and the p-type reflective contact layer 152 is formed at the other end by the insulating layer 152 including the metal nanoparticles 151 110, the p-type nitride layer 120, and the active layer 130 are insulated. The lower end of the n-type electrode 153 is in contact with the conductive layer 102.

In the present invention, the metal nanoparticles 151 may be formed of one metal such as silver (Ag), aluminum (Al), copper (Cu), gold (Au), Ni, Ti, Pt, Pd, Cr, ), And the size is preferably about 1 nm to 300 nm in order to improve the plasmon resonance effect.

The light emitting device 100 of the present invention generates a surface plasmon resonance phenomenon in which electrons located on the surface of the metal nanoparticles are resonated by the interaction between the light generated in the active layer 130 and the metal nanoparticles 151 The light emitting recombination speed of the active layer 130 is increased and the luminous efficiency can be increased.

Meanwhile, in the light emitting device 100 of the present invention, the p-type reflective contact layer 110 can reflect the light generated in the active layer 130 and the light amplified by the plasmon resonance effect upward to improve the light output .

In addition, the light emitting device 100 of the present invention provides a structure in which the n-type electrode 153 is not exposed to the upper portion of the device, so that degradation in luminous efficiency due to absorption of light in the electrode, And it is possible to improve the light output by inducing an increase in effective light emission area by a uniform current spreading effect.

FIG. 2 is a cross-sectional view of a light emitting device according to a second embodiment of the present invention. FIG. 3 is a cross-sectional view of a light emitting device according to a third embodiment of the present invention. The same reference numerals are used for the same components, and redundant descriptions are omitted.

2, and 3, the p-type nitride layer 120 is formed separately from the plasmon generating portion 150 by using an insulating material 162 (172) including metal nanoparticles 161 (171) 2 plasmon generating units 160 and 170 so that the second plasmon generating units 160 and 170 disposed in the vicinity of the plasmon generating unit 150 simultaneously generate a local plasmon resonance effect The internal quantum efficiency and the light extraction efficiency can be improved to improve the light output.

3, the second plasmon generator 170 may penetrate the active layer 130 to form a trench structure up to a partial region of the n-type nitride layer 140. Referring to FIG.

On the other hand, the second plasmon generator 160 (170) of the trench structure of the second embodiment (see FIG. 2) and the third embodiment (see FIG. 3) It should be understood that it may be provided in the vicinity.

FIG. 4 is a view illustrating a manufacturing process of the light emitting device according to the present invention. Referring to FIG. 4, a method of manufacturing the light emitting device according to the present invention will be described.

In the first step (a), the n-type nitride layer 140, the active layer 130, and the p-type nitride layer 120 are sequentially stacked on the growth substrate 10. Although not shown, a buffer layer may be grown first to mitigate lattice mismatch between the growth substrate 10 and the n-type nitride layer 140 prior to growing the n-type nitride layer 140 on the growth substrate 10 . This buffer layer may be a low temperature nucleation layer including AlN or GaN.

In this embodiment, the p-type nitride layer 120 and the n-type nitride layer 140 are made of aluminum-indium-gallium-nitrogen (AlxInyGazN: x + y + z = 1), and the active layer is formed by a multi quantum well (MQW) structure formed of a nitride semiconductor containing indium and gallium, aluminum and gallium .

On the other hand, the growth substrate 10 can be a sapphire substrate which is easy to grow the nitride semiconductor and is stable at high temperature. The growth of the nitride semiconductor layer can be sequentially performed using semiconductor growth equipment such as MOCVD, molecular beam epitaxy (MBE), hybrid vapor deposition (HVPE), etc. In particular, the organic metal chemical vapor deposition .

The second step (b) uses the photoresist as a mask to penetrate the p-type nitride layer 120 and the active layer 130 to a certain depth of the n-type nitride layer 140 to form the trench structure TS . The trench structure may have one or more regular or irregular patterned shapes in the light emitting device. In addition, the arrangement period, size, and number of the patterns can be selected in order to maximize the surface plasmon resonance effect and luminous efficiency of the light emitting device. An ICP (Inductively Coupled Plasma) / RIE (Reactive Ion Etching) method can be used as an etching method.

In the third step (c), the p-type reflective contact layer 110 is formed on the surface of the p-type nitride layer 120 after masking using a photo-resist on the surface other than the trench structure formation. Remove the photogistosts in the mashed area using the lift-off method.

The fourth step (d) (e) (f) includes the step of forming the p-type reflective contact layer 110 including the surface of the trench structure TS so that the metal nanoparticles 151 are electrically insulated and distributed in the trench structure TS. Insulating layers 103 and 152 are formed on the surface. For reference, the insulating layer formed on the surface of the trench structure (TS) is denoted by reference numeral 152 in the present embodiment, and the insulating layer formed on the surface of the p-type reflective contact layer 110 is denoted by reference numeral 103. However, It is to be understood that an insulating layer may be formed.

In the fourth step, metal nanoparticles may be formed by well-known methods such as annealing, dipping, spin coating, and spray-coating. The size density of the metal nanoparticles determining the properties of the plasmon resonance effect can be determined by annealing time and temperature, dipping time and frequency, spin coating time and speed.

The metal nanoparticles 151 are formed in the trench structure TS after the first insulating layer 103a is formed to have a small thickness on the surface of the trench structure TS and the p-type reflective contact layer 110, (E) on the surface of the first insulating layer 103a in the trench structure TS and filling the trench structure TS with an insulating material, a trench structure TS is again formed for n-type electrode contact with the n-type nitride layer 140 And the insulating layers 103 and 152 are formed (f). The formation of the first insulating layer 103a can prevent leakage through metal and metal nanoparticles which may cause a decrease in luminescence characteristics when the metal is directly in contact with the quantum well. As a specific example of the present invention, a material usable as an insulating layer can be silicon dioxide (SiO 2), silicon nitride (Si 3 N 4), spin-on-glass (SOG), or the like, which are generally used as dielectric materials in the semiconductor field. In addition, although the method of forming the re-trench for contacting the n-type electrode is not limited to a specific method, wet chemical etching or dry etching can be used by using a photoresist as a mask. .

In the fifth step (g), the n-type electrode 151 is formed by filling the trench structure formed in the fourth step with a conductive material for electrical connection with the n-type nitride layer 140.

In the sixth step (h), a conductive layer 102 is formed on the surface of the n-type electrode 151 and the insulating layer 103, and the substrate 101 is bonded. A conductive layer used for substrate bonding (adhesion) may use a eutectic metal material such as AuSn. The bonding substrate prevents the light emitting device including the semiconductor layer and the active layer from being bent or partially dropped during the lift-off process for separating the growth substrate, and stably supports the light emitting device.

In a seventh step (i), the growth substrate 10 bonded to the n-type nitride layer 140 is separated.

The growth substrate 10 may be separated by a lift off process, and the lift-off process may be a laser lift-off process using a laser or a chemical lift-off process for separating chemically.

On the other hand, the surface of the n-type nitride layer 140 on which the growth substrate 10 is separated can form a roughness 141 in order to maximize the effect of emitting light generated in the device to the outside, The shape of the roughness may be spherical, hemispherical, hexagonal, or microlens array.

Next, the light emitting device thus manufactured may include a step (j) of forming a p-type electrode 111 for electrical connection to the p-type reflective contact layer 110 after sidewall etching.

Meanwhile, although not described in detail in this embodiment, the second plasmon generator may be formed similar to the process (b) to (f) for forming the plasmon generator. The distance between the active layer and the plasmon generating part (metal nanoparticle forming part) is particularly important, and the metal nanoparticles of the second plasmon generating part should be distributed at a certain distance or less from the active layer under conditions in which plasmon resonance can occur. Specifically, .

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. It will be apparent to those of ordinary skill in the art.

100: light emitting element 101: substrate
102: conductive layer 103: insulating layer
110: p-type reflective contact layer 111: p-type electrode
120: p-type nitride layer 130: active layer
140: n-type nitride layer 150: plasmon generator
151: metal nanoparticles 152: insulating layer
153: n-type electrode 160, 170: second plasmon generator

Claims (8)

a p-type reflective contact layer;
A p-type nitride layer formed on the p-type reflective contact layer;
An active layer formed on the p-type nitride layer;
An n-type nitride layer formed on the active layer;
A n-type electrode having an n-type electrode formed on the p-type reflective contact layer, the p-type nitride layer, and the active layer, the n-type nitride layer having a front end contacted with the n-type nitride layer, And a light emitting element. The light emitting device according to claim 1, wherein the p-type nitride layer further includes a second plasmon generator having an insulating material including metal nanoparticles. 3. The light emitting device of claim 2, wherein the second plasmon generator is located through the active layer. The light emitting device according to claim 2, wherein the metal nanoparticles of the second plasmon generator are distributed within 100 nm from the active layer. The light emitting device according to any one of claims 1 to 4, wherein the metal nanoparticles have a size of 1 nm to 100 nm. A first step of sequentially laminating an n-type nitride layer, an active layer, and a p-type nitride layer on a growth substrate;
A second step of penetrating the p-type nitride layer and the active layer to form a trench structure to a predetermined depth of the n-type nitride layer;
A third step of forming a p-type reflective contact layer on the surface of the p-type nitride layer;
A fourth step of forming an insulating layer on the surface of the p-type reflective contact layer including the surface of the trench structure so that metal nanoparticles are insulated and distributed in the trench structure;
A fifth step of forming an n-type electrode in the trench structure of the fourth step;
A sixth step of forming a conductive layer on the surface of the n-type electrode and the insulating layer and bonding the substrate;
And a seventh step of separating the growth substrate bonded to the n-type nitride layer. 7. The method of claim 6, further comprising forming a p-type electrode in the p-type reflective contact layer after the sidewall etching after the seventh step. [7] The method of claim 6, wherein the seventh step further comprises forming a roughness on the surface of the n-type nitride layer on which the growth substrate is separated.

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