WO2011008038A2

WO2011008038A2 - Group iii nitride semiconductor light-emitting device

Info

Publication number: WO2011008038A2
Application number: PCT/KR2010/004628
Authority: WO
Inventors: 김창태; 남기연
Original assignee: 주식회사 에피밸리
Priority date: 2009-07-15
Filing date: 2010-07-15
Publication date: 2011-01-20
Also published as: KR101100684B1; KR20110006778A; CN102549782A; TW201117425A; WO2011008038A3

Abstract

The present disclosure relates to a group III nitride semiconductor light-emitting device, and more particularly, to a group III nitride semiconductor light-emitting device which emits light through electron-hole recombination, and which comprises: a first electrode and a second electrode for supplying a current for the electron-hole recombination; a first branch electrode branched from the first electrode; and a second branch electrode branched from the second electrode, wherein the second branch electrode has a thickness at least a portion of which is different from the thickness of the first branch electrode.

Description

Group III nitride semiconductor light emitting device

The present disclosure relates to a group III nitride semiconductor light emitting device as a whole, and more particularly, to a group III nitride semiconductor light emitting device having an electrode structure for current diffusion.

Here, the group III nitride semiconductor light emitting device refers to a semiconductor optical device that generates light through recombination of electrons and holes, for example, a group III nitride semiconductor light emitting device. The group III nitride semiconductor consists of a compound of Al (x) Ga (y) In (1-x-y) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). In addition, the GaAs group III nitride semiconductor light emitting element used for red light emission, etc. are mentioned.

This section provides backgound information related to the present disclosure which is not necessarily prior art.

1 is a view illustrating an example of a conventional Group III nitride semiconductor light emitting device, wherein the Group III nitride semiconductor light emitting device is grown on the substrate 10, the buffer layer 20 grown on the substrate 10, and the buffer layer 20. n-type group III nitride semiconductor layer 30, active layer 40 grown on n-type group III nitride semiconductor layer 30, p-type group III nitride semiconductor layer 50 grown on active layer 40, p-type 3 The p-side electrode 60 formed on the group nitride semiconductor layer 50, the p-side bonding pad 70 formed on the p-side electrode 60, the p-type group III nitride semiconductor layer 50 and the active layer 40 The n-side electrode 80 and the passivation layer 90 are formed on the n-type group III nitride semiconductor layer 30 exposed by mesa etching.

As the substrate 10, a GaN-based substrate is used as the homogeneous substrate, and a sapphire substrate, a SiC substrate, or a Si substrate is used as the heterogeneous substrate. Any substrate may be used as long as the group III nitride semiconductor layer can be grown. When a SiC substrate is used, the n-side electrode 80 may be formed on the SiC substrate side.

The group III nitride semiconductor layers grown on the substrate 10 are mainly grown by MOCVD (organic metal vapor growth method).

The buffer layer 20 is intended to overcome the difference in lattice constant and thermal expansion coefficient between the dissimilar substrate 100 and the group III nitride semiconductor. US Pat. A technique for growing an AlN buffer layer having a thickness of US Pat. No. 5,290,393 describes Al (x) Ga (1-x) N having a thickness of 10 kPa to 5000 kPa at a temperature of 200 to 900 C on a sapphire substrate. (0 ≦ x <1) A technique for growing a buffer layer is described, and US Patent Publication No. 2006/154454 discloses growing a SiC buffer layer (seed layer) at a temperature of 600 ° C. to 990 ° C., followed by In (x Techniques for growing a Ga (1-x) N (0 <x≤1) layer are described. Preferably, the undoped GaN layer is grown prior to the growth of the n-type Group III nitride semiconductor layer 300, which may be viewed as part of the buffer layer 20 or as part of the n-type Group III nitride semiconductor layer 30. .

In the n-type group III nitride semiconductor layer 30, at least a region (n-type contact layer) in which the n-side electrode 80 is formed is doped with an impurity, and the n-type contact layer is preferably made of GaN and doped with Si. . U. S. Patent No. 5,733, 796 describes a technique for doping an n-type contact layer to a desired doping concentration by controlling the mixing ratio of Si and other source materials.

The active layer 40 is a layer that generates photons (light) through recombination of electrons and holes, and is mainly composed of In (x) Ga (1-x) N (0 <x≤1), and one quantum well layer (single quantum wells) or multiple quantum wells.

The p-type group III nitride semiconductor layer 50 is doped with an appropriate impurity such as Mg, and has an p-type conductivity through an activation process. U.S. Patent No. 5,247,533 describes a technique for activating a p-type group III nitride semiconductor layer by electron beam irradiation, and U.S. Patent No. 5,306,662 annealing at a temperature of 400 DEG C or higher to A technique for activating is described, and US Patent Publication No. 2006/157714 discloses a p-type III-nitride semiconductor layer without an activation process by using ammonia and a hydrazine-based source material together as a nitrogen precursor for growing the p-type III-nitride semiconductor layer. Techniques for having this p-type conductivity have been described.

The p-side electrode 60 is provided so that the current is well supplied to the entire p-type group III nitride semiconductor layer 500, and US Patent No. 5,563,422 is formed over almost the entire surface of the p-type group III nitride semiconductor layer. A light-transmitting electrode made of Ni and Au in ohmic contact with the p-type III-nitride semiconductor layer 500 is described. US Pat. No. 6,515,306 discloses n on the p-type III-nitride semiconductor layer. A technique is described in which a type superlattice layer is formed and then a translucent electrode made of indium tin oxide (ITO) is formed thereon.

On the other hand, the p-side electrode 60 can be formed to have a thick thickness so as not to transmit light, that is, to reflect the light toward the substrate side, this technique is referred to as flip chip (flip chip) technology. U. S. Patent No. 6,194, 743 describes a technique relating to an electrode structure including an Ag layer having a thickness of 20 nm or more, a diffusion barrier layer covering the Ag layer, and a bonding layer made of Au and Al covering the diffusion barrier layer.

The p-side bonding pad 70 and the n-side electrode 80 are for supplying current and wire bonding to the outside, and US Patent No. 5,563,422 describes a technique in which the n-side electrode is composed of Ti and Al.

The passivation layer 90 is formed of a material such as silicon dioxide and may be omitted.

Meanwhile, the n-type III-nitride semiconductor layer 30 or the p-type III-nitride semiconductor layer 50 may be composed of a single layer or a plurality of layers, and recently, the substrate 10 may be formed by laser or wet etching. A technique for manufacturing a vertical light emitting device by separating from group III nitride semiconductor layers has been introduced.

2 is a view showing an example of the electrode structure described in US Patent No. 5,563,422, wherein the p-side bonding pad 70 and the n-side electrode 80 are located at diagonal corners of the light emitting device to improve current spreading. It is described.

3 is a view showing an example of the electrode structure described in US Pat. No. 6,307,218, and the like between the p-

side bonding pads

71 and 71 and the n-

side electrodes

81 and 81 as the light emitting device becomes larger. A technique for improving current spreading by having

branch electrodes

91 and 91 at intervals is described.

However, the light emitting device having such an electrode structure has a problem in that current may be concentrated in a region R close to the p-

side bonding pads

71 and 71 or the n-

side electrodes

81 and 81.

This is described later in the section titled 'Details of the Invention.'

This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all, provided that this is a summary of the disclosure. of its features).

According to one aspect of the present disclosure (According to one aspect of the present disclosure), in the Group III nitride semiconductor light emitting device for generating light through the recombination of electrons and holes, supplying a current for recombination of electrons and holes A first electrode and a second electrode; A first branch electrode extending from the first electrode; And a second branch electrode extending from the second electrode, wherein at least a portion of the second branch electrode has a thickness different from that of the first branch electrode.

This will be described later in the section on Embodiments of the Invention.

1 is a view showing an example of a conventional group III nitride semiconductor light emitting device,

2 is a view showing an example of an electrode structure described in US Patent No. 5,563,422;

3 is a view showing an example of an electrode structure described in US Pat. No. 6,307,218;

4 is a view illustrating an example of an electrode structure of a group III nitride semiconductor light emitting device according to the present disclosure;

5 is a view showing another example of an electrode structure of a group III nitride semiconductor light emitting device according to the present disclosure;

6 is a view illustrating still another example of an electrode structure of a group III nitride semiconductor light emitting device according to the present disclosure;

7 is a view showing another example of an electrode structure of a group III nitride semiconductor light emitting device according to the present disclosure;

8 to 10 are enlarged views of parts A, B, and C in FIG. 7, respectively.

The present disclosure will now be described in detail with reference to the accompanying drawing (s).

However, in the description, a description of a configuration overlapping with that described in the background art of the present disclosure will be omitted and will be omitted below.

4 is a view illustrating an example of an electrode structure of a group III nitride semiconductor light emitting device according to the present disclosure. An electrode structure of the group III nitride semiconductor light emitting device according to the present disclosure extends from the

electrodes

110 and 120 and each electrode. Branched electrodes 113,123.

In the group III nitride semiconductor light emitting device, the

electrodes

110 and 120 may be electrically connected to the first electrode 110 electrically connected to any one of an n-type III-nitride semiconductor layer and a p-type III-nitride semiconductor layer. It consists of a second electrode 120 connected to.

In this example, each of the first electrode 110 and the second electrode 120 may be provided as one p-side bonding pad or one n-side electrode.

Each of the

branch electrodes

113 and 123 may be provided as one branch electrode, but a case in which a plurality of

branch electrodes

113a, 113b, 113c, 123a and 123b are provided will be described.

That is, the

branch electrodes

113 and 123 may include the plurality of

first branch electrodes

113a, 113b and 113c extending from the first electrode 110 and the plurality of second branch electrodes extending from the second electrode 120. 123a, 123b).

In the present example, at least two

branch electrodes

113 and 123 of the

branch electrodes

113 and 123 have different thicknesses.

This is to change the magnitude of the current flowing to each of the

branch electrodes

113 and 123.

As a result, a phenomenon in which current does not spread evenly between the first electrode 110 and the second electrode 120 and is concentrated in an arbitrary region, that is, a problem in which the current density becomes uneven is prevented.

More specifically described as follows.

In this example, the first electrode 110 and the second electrode 120 are provided symmetrically with respect to the center of the light emitting device, and are provided on the outer portion of the light emitting device.

Among the

first branch electrodes

113a, 113b and 113c extending from the first electrode 110, the first branch electrode 113a is positioned in the first region R1, and the first branch electrode 113b is second The first branch electrode 113b is positioned in the region R2, and the first branch electrode 113b is positioned in the third region R3.

Among the

second branch electrodes

123a and 123b extending from the second electrode 120, the second branch electrode 123a is positioned between the first branch electrode 113a and the first branch electrode 113b. The second branch electrode 123b is positioned between the first branch electrode 113b and the first branch electrode 113c.

In this case, in consideration of the arrangement of the first electrode 110 and the second electrode 120 and the arrangement of the branch electrodes 112 and 113, a virtual straight line connecting the first electrode 110 and the second electrode 120. The current flows to the first region R1 positioned at the second region R2 and the third region R3, and the current flows to the second region R2 as compared to the third region R3.

To prevent this, in the present example, the thickness T2 of the second branch electrode 123a is provided to be thicker than the thickness T1 of the first branch electrode 113a, and the thickness of the first branch electrode 113b is increased. The thickness T3 is thicker than the thickness T2 of the second branch electrode 123a.

In addition, the thickness of the branch electrode farther from the center of the light emitting device is provided. That is, the thickness of the branch electrode in FIG. 4 is provided in order of T1 <T2 <T3 <T4 <T5.

Therefore, since the magnitude of the current flowing through the branch electrode positioned in the region where the current is relatively less driven is greater than the magnitude of the current flowing through the branch electrode positioned in the region where the current is relatively driven, the problem of current flow is alleviated or solved. You can do it.

Meanwhile, in the present example, since the flow of current occurs between the

first branch electrodes

113a, 113b and 113c and the

second branch electrodes

123a and 123b, the current density is more uniformly distributed. The one

branch electrodes

113a, 113b and 113c and the

second branch electrodes

123a and 123b are preferably alternately positioned one by one in the outer direction from the center of the light emitting device.

In addition, in the present example, the first electrode 110 and the second electrode 120 are positioned so that an imaginary straight line connecting the first electrode 110 and the second electrode 120 passes through the center of the light emitting device. Since the

first branch electrodes

113a, 113b and 113c and the

second branch electrodes

123a and 123b positioned at symmetry with respect to an imaginary straight line may have the same thickness, the first and second The thickness design of the branch electrodes becomes simpler.

In addition, in the present example, the shape of the first electrode 110 and the second electrode 120 is not limited to the circle shown in FIG. 4, and may be provided as an ellipse, a polygon, or the like.

In the present example, the thicknesses T1, T2, and T3 of the branch electrodes are values that can be determined through experiments according to the size, shape, distribution shape of the branch electrodes, position of the electrode, and shape of the light emitting device.

That is, the objective of the present disclosure may be achieved by thinly adjusting the thickness of the branch electrode passing through the region where the current density increases through experiments.

On the other hand, in the present example, the spacing between the branch electrodes may be provided uniformly, but the spacing in the first region R1 where the current density is relatively large is in the second region R2 where the current density is relatively small. It is preferable to provide larger than the interval of.

5 is a view illustrating another example of an electrode structure of the group III nitride semiconductor light emitting device according to the present disclosure. The electrode structure according to the present example is similar to the example of the electrode structure described above, but includes the first electrode 210. ) And at least one of the second electrodes 220 are different in that two or

more split electrodes

211 and 212 supplied with divided currents are joined to each other.

Bonding wires to which current is supplied are coupled to each of the

split electrodes

211 and 212.

As a result, the current supplied through one bonding wire is dividedly supplied through the plurality of bonding wires, thereby enabling stable current supply.

In particular, the larger the area of the light emitting device is, the larger the amount of current for driving the light emitting device is, which is useful in this case.

In addition, in the present example, the thickness of the

branch electrodes

213 and 223 is the same as that of the above-described example. It is provided thinner than the thickness of.

In addition, in the present example, it is preferable that an imaginary straight line connecting the first electrode 210 and the second electrode 220 is positioned past the center of the light emitting device.

6 is a view illustrating another example of an electrode structure of the group III nitride semiconductor light emitting device according to the present disclosure. The electrode structure according to the present example is similar to the example of the electrode structure described above. At least one of the 310 and the second electrode 320 is different in that two or more

divided electrodes

311 and 312 supplied with divided currents are spaced apart from each other.

This is to achieve stable current supply by dividing and supplying the driving current of the light emitting device as the area of the light emitting device increases as in the above-described example.

In addition, by positioning the divided

electrodes

311 and 312 spaced apart from each other, it is possible to achieve uniform current density.

Also, in the present example, the thickness of the branch electrodes 313 and 323 is the same as that of the above-described example, and the branch electrodes positioned in the region where the current density is relatively high are located in the region where the current density is relatively low. It is provided thinner than the thickness of.

7 is a view illustrating another example of an electrode structure of the group III nitride semiconductor light emitting device according to the present disclosure. The electrode structure according to the present example is similar to the example of the electrode structure described above, but includes the first branch electrode. The thickness of at least one branch electrode of the

branch electrodes

413a, 413b, and 413c and the

second branch electrodes

423a and 423b is changed along its length direction.

This is to alleviate or eliminate the difference in current density by varying the thickness of each part, considering that a difference in current density occurs in each region where each part of one branch electrode is located.

That is, the thickness of the portion located in the region where the current density is relatively high among the portions forming one branch electrode is provided to be thinner than the thickness of the portion positioned in the region where the current density is relatively low.

8 to 10, when a part of the second branch electrode or a part of the first branch electrode is positioned around the first electrode 410 or the second electrode 420, the first electrode 410 and the first electrode 410 are located. A relatively high current density is formed between a portion of the second branch electrode 423b, or between the second electrode 420 and a portion of the

first branch electrodes

413b, 413c, so as to eliminate or alleviate it. The thickness a1, b1, c1 of the electrode or a part of the second branch electrode is thinner than the thickness a2, b2, c2 of the remaining part.

Hereinafter, various embodiments of the present disclosure will be described.

(1) A group III nitride semiconductor light emitting element comprising a plurality of branch electrodes having different thicknesses. This can improve the concentration of the current.

(2) A group III nitride semiconductor light emitting element comprising a branch electrode having a thickness changed in the longitudinal direction. As a result, the concentration of current can be relaxed or eliminated.

(3) A group III nitride semiconductor light emitting element comprising an electrode in which a plurality of split electrodes are bonded together so that a plurality of wires can be bonded together with the embodiments of (1) or (2). This can improve the concentration of current even if the wire is poorly bonded to any of the split electrodes.

(4) A group III nitride semiconductor light emitting element comprising an electrode in which a plurality of split electrodes are positioned to be spaced apart from each other in accordance with the embodiment of (1) or (2). Thereby, the current density of a large area light emitting element can be improved uniformly.

According to the group III nitride semiconductor light emitting device according to the present disclosure, the current density between different branch electrodes can be made uniform, and the current density of the entire light emitting device can be improved uniformly.

According to the group III nitride semiconductor light emitting device according to the present disclosure, the current density formed around one branch electrode can be made uniform, and the current density of the entire light emitting device can be improved uniformly.

According to the group III nitride semiconductor light emitting device according to the present disclosure, even if a wire is poorly bonded to any one of the split electrodes, the concentration of current can be improved.

According to the group III nitride semiconductor light emitting device according to the present disclosure, the current density imbalance due to the large driving current of the large area light emitting device can be improved.

Claims

In the group III nitride semiconductor light emitting device for generating light through the recombination of electrons and holes,

A first electrode and a second electrode supplying a current for recombination of electrons and holes;

A first branch electrode extending from the first electrode; And

And a second branch electrode extending from the second electrode, wherein at least a portion of the second branch electrode has a thickness different from that of the first branch electrode.
The method according to claim 1,

The group III nitride semiconductor light-emitting device having a thickness of the second branch electrode having the same thickness in the longitudinal direction and different from the thickness of the first branch electrode.
The method according to claim 2,

The thickness of the branch electrode positioned in the second region having a relatively small current density is thicker than the thickness of the branch electrode positioned in the first region having a relatively large current density formed in the light emitting device through the first electrode and the second electrode. Group III nitride semiconductor light emitting device.
The method according to claim 2,

The group III nitride semiconductor light emitting device of claim 1, wherein the first branch electrodes and the second branch electrodes are alternately positioned in the outer direction from the center of the light emitting element.
The method according to claim 3,

The first electrode and the second electrode are each provided with one electrode, the group III nitride semiconductor light emitting device, characterized in that the virtual straight line connecting the first electrode and the second electrode is located through the center of the light emitting device.
The method according to claim 3,

At least one of the first electrode and the second electrode is provided by joining two or more divided electrodes supplied with a divided current, and a virtual straight line connecting the first electrode and the second electrode is positioned past the center of the light emitting device. Group III nitride semiconductor light emitting device.
The method according to claim 3,

At least one of the first electrode and the second electrode is a group III nitride semiconductor light emitting device, characterized in that provided by at least two divided electrodes which are spaced apart by a predetermined distance and connected by the first branch electrode or the second branch electrode. .
The method according to claim 1,

The group III nitride semiconductor light emitting device of claim 2, wherein the thickness of the second branch electrode is changed in the longitudinal direction.
The method according to claim 8,

Part 3 of the second branch electrode positioned adjacent to the first electrode, or a portion of the first branch electrode positioned adjacent to the second electrode is thinner than the rest of the branch electrode group III Nitride semiconductor light emitting device.
The method according to claim 8,

At least one electrode of the first electrode and the second electrode is provided with at least two divided electrodes which are spaced apart from each other,

A group III nitride semiconductor light emitting device, characterized in that a portion of the branch electrode positioned adjacent to each split electrode is thinner than the rest of the branch electrode.