KR20090028931A

KR20090028931A - Semiconductior light emitting device

Info

Publication number: KR20090028931A
Application number: KR20070094083A
Authority: KR
Inventors: 김선운; 김현경; 이동주; 한재호
Original assignee: 삼성전기주식회사
Priority date: 2007-09-17
Filing date: 2007-09-17
Publication date: 2009-03-20

Abstract

The present invention relates to a semiconductor light emitting device, and an embodiment of the present invention provides a substrate, a light emitting structure formed by sequentially stacking a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on the substrate, A semiconductor light emitting device includes at least one through hole formed in the stacking direction to penetrate the light emitting structure, and first and second electrodes formed to be electrically connected to the first and second conductive semiconductor layers, respectively.

According to the present invention, it is possible to provide a semiconductor light emitting device having improved light extraction efficiency by forming a hole penetrating the light emitting device.

Description

Semiconductor light emitting device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device and a method of manufacturing the same, and more particularly, to a semiconductor light emitting device and a method of manufacturing the light extraction efficiency is improved by forming a hole through the light emission.

A light emitting diode (LED), which is one of semiconductor light emitting devices, is a semiconductor device capable of generating light of various colors based on recombination of electrons and holes at a junction portion of a p and n type semiconductor when current is applied thereto. These LEDs have a number of advantages over filament based light emitting devices, such as long life, low power, excellent initial driving characteristics, high vibration resistance, and high tolerance for repetitive power interruptions. In recent years, group III nitride semiconductors capable of emitting light in a blue short wavelength region have been in the spotlight.

1 is a cross-sectional view showing a semiconductor light emitting device according to the prior art.

The semiconductor light emitting device 10 includes an n-type semiconductor layer 12, an active layer 13, a p-type semiconductor layer 14, and a transparent electrode layer 15 sequentially grown on the sapphire substrate 11. The n-side and p-side electrodes 16a and 16b are formed on the n-type semiconductor layer 12 and the transparent electrode layer 15, respectively.

In the case of the semiconductor light emitting device 10, not all light generated from the active layer 13 can be emitted to the outside, it is necessary to minimize the ratio of light trapped inside the light emitting device by total reflection in order to improve the luminous efficiency. have. In particular, in the case of a light emitting device using a nitride semiconductor, the degree of reflection varies depending on the angle of incidence when incident on the air / GaN interface. In this case, theoretically, when the incident angle is 26 ° or more, all light generated in the active layer is totally internally reflected.

Therefore, there is a need in the art for a method of improving the luminous efficiency by reducing the total internal reflection.

The present invention is to solve the above problems, an object of the present invention is to provide a semiconductor light emitting device and a method of manufacturing the light extraction efficiency is improved by forming a hole through the light emitting device.

In order to achieve the above object, one embodiment of the present invention,

A light emitting structure formed by stacking a substrate, a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer sequentially on the substrate, at least one through hole formed in the stacking direction to penetrate the light emitting structure, Provided is a semiconductor light emitting device including first and second electrodes formed to be electrically connected to first and second conductive semiconductor layers, respectively.

In this case, the through hole is preferably formed to extend through the substrate.

In some embodiments, the through hole formed in the substrate may have a smaller size toward the first conductive semiconductor layer.

In addition, the through hole formed in the light emitting structure may be larger in size toward the second conductive semiconductor layer in the first conductive semiconductor layer.

Considering the aspects for improving light extraction efficiency and preventing holes from filling in the process of forming the light emitting structure, the size of the through hole is preferably 3 to 30 μm. Furthermore, the shape of the through hole is preferably circular.

On the other hand, in the case of a horizontal structure semiconductor light emitting device, it is preferable that the first conductive semiconductor layer is an n-type semiconductor layer, and the second conductive semiconductor layer is a p-type semiconductor layer.

Additionally, the transparent electrode layer formed on the second conductive semiconductor layer may be further included. In this case, the through hole may be formed to extend through the transparent electrode layer.

The first electrode may be formed in a region where the active layer is not formed on an upper surface of the first conductive semiconductor layer, and the second electrode may be formed on the transparent electrode layer.

In another embodiment of the present invention, a vertical structure semiconductor light emitting device may be provided, in which case, the substrate is a conductive substrate, the first electrode is formed on the lower surface of the conductive substrate, and the second electrode is the second conductive. It may be formed on the upper surface of the type semiconductor layer.

In the case of such a vertical structure semiconductor light emitting device, it is preferable that the first conductive semiconductor layer is a p-type semiconductor layer, and the second conductive semiconductor layer is an n-type semiconductor layer.

As described above, according to the present invention, it is possible to provide a semiconductor light emitting device having improved light extraction efficiency by forming a hole penetrating the light emitting device.

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

However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

2A is a cross-sectional view illustrating a semiconductor light emitting device according to an embodiment of the present invention, and FIG. 2B is a perspective view.

2A and 2B, the semiconductor light emitting device 20 according to the present embodiment may include an n-type semiconductor layer 22 and an active layer 23 sequentially formed on the sapphire substrate 21 and the sapphire substrate 21. and a p-type semiconductor layer 24 and a transparent electrode layer 25, in addition to the n-side and p-side electrodes 26a and 26b.

In addition, the semiconductor light emitting device 20 includes the sapphire substrate 21, the n-type semiconductor layer 22, the active layer 23, the p-type semiconductor layer 24, and the transparent electrode layer 25 to improve light extraction efficiency. A plurality of through holes H penetrate is formed.

Hereinafter, the components constituting the semiconductor light emitting device 20 will be described in detail.

The sapphire substrate 21 is provided as a substrate for semiconductor single crystal growth, and has a hexagonal-Rhombo R3c symmetry and has a lattice constant of 13.001 Å in the c-axis direction and 4.765 Å in the a-axis direction. Have a distance between them. In particular, the C surface of the sapphire substrate 21 is relatively easy to grow a nitride thin film, and is mainly used as a nitride growth substrate because it is stable at high temperatures.

In this embodiment, in order for the nitride thin film to have a through hole H, a hole is preferentially formed in the sapphire substrate 21, and a nitride thin film is formed along the hole of the sapphire substrate 21 to form a through hole. A structure having (H) can be obtained.

As described above, although the hole is formed in the sapphire substrate 21 in terms of the process, the present invention is not limited thereto, and the hole may not be formed in the sapphire substrate 21 depending on the embodiment. .

On the other hand, the semiconductor single crystal growth substrate that can be employed in the present invention is not limited to the sapphire substrate 21, SiC, MgAl ₂ O ₄ , MgO, LiAlO ₂ and LiGaO ₂ and the like can be generally used for single crystal growth It is also possible to adopt a substrate made.

Although not shown, a buffer layer may be first grown on the sapphire substrate 21 and then the n-type semiconductor layer 22 may be grown.

The n-type and p-type semiconductor layers 22 and 24 and the active layer 23 constituting the light emitting structure will be described. First, the n-type and p-type semiconductor layers 22 and 24 are preferably made of a nitride semiconductor. In the present specification, the term "nitride semiconductor" means a binary component or a three component system represented by Al x In y Ga (1-xy) N (0≤x≤1, 0≤y≤1, 0≤x + y≤1). It means a ternary or quaternary compound semiconductor.

That is, the n-type and p-type semiconductor layers 22 and 24 have an Al x In y Ga (1-xy) N composition formula, where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ x + y ≦ 1. The n-type impurity and the p-type impurity may be made of a semiconductor material, and typically, GaN, AlGaN, InGaN. In addition, Si, Ge, Se, Te or C may be used as the n-type impurity, and the p-type impurity may be representative of Mg, Zn or Be.

The active layer 23 is composed of an undoped nitride semiconductor layer having a single or multiple quantum well structure, and emits light having a predetermined energy by recombination of electrons and holes.

The n-type and p-type semiconductor layers 22 and 24 and the active layer 23 are formed of a semiconductor single crystal growth process, in particular, an organometallic vapor deposition method (MOCVD), a molecular beam growth method (MBE), and the like known as a nitride single crystal growth process. It can be grown by a method such as hybrid vapor deposition (HVPE).

Since the transparent electrode layer 25 formed on the p-type semiconductor layer 24 performs an ohmic contact function and is positioned on a light emission path, the transparent electrode layer 25 is preferably made of a material having high light transmittance. Preferably, the transparent electrode layer 25 may be made of ITO, ZnO, In ₂ O ₃ , SnO ₂ .

As described above, the semiconductor light emitting device 20 according to the present exemplary embodiment includes a through hole H formed through the sapphire substrate 21, the light emitting structures 22, 23, and 24, and the transparent electrode layer 25. do.

The interfacial area with the outside (air) from which the light is emitted to the outside from the light emitting device 20 may be increased by the through hole H. Accordingly, light trapped inside by the total reflection in the prior art may be moved to the outside. It provides more opportunities for release.

In addition, since the incident angle of light may be more varied at the external interface by the through hole (H) than in the conventional case, the light extraction efficiency may be improved by such a factor. The effect of improving the light extraction efficiency by the through hole H may be understood in more detail with reference to FIG. 4, which illustrates some of the paths of light emitted from the active layer 23.

On the other hand, as described above, the hole of the sapphire substrate 21 may be previously formed by a laser or the like, the hole formed in the light emitting structure may be naturally formed on the sapphire substrate 21 through a single crystal growth process. In this case, since the hole may be filled through the lateral growth in the single crystal growth process, it is necessary to appropriately select the size (W) of the through hole (H). In addition, when the size W of the through hole H is too large, the area of the active layer 23 may be so small that the luminous efficiency may be reduced.

Considering these matters, the size W of the through hole H is preferably 3 to 30 μm. That is, when the size W of the through hole H is smaller than 3 μm, problems may occur in the formation of the hole due to lateral growth. When the size of the through hole H is smaller than 30 μm, the hole may become too large, resulting in a decrease in luminous efficiency. Problems such as the inhibition of stability may occur. On the other hand, in the present embodiment has been described the preferred size (W) on the basis of the case where the through-hole (H) is circular, the above conditions can be applied even if the shape other than circular.

In addition, the probability that the tube discharged from the active layer 23 by the through hole H may be increased to the outside, but at the same time, the area of the active layer 23 may be reduced. Therefore, the size and number of the through holes H need to be appropriately adjusted. Particularly, when the size of the light emitting device is relatively large, for example, when the size of the light emitting device is about 1000 μm × 1000 μm, the reduction of the active layer area is relatively insignificant. Therefore, the adoption of the through hole H may be more effective. Can be.

In relation to the shape of the through hole (H), as shown in Figure 2b the circular may be generally employed, but is not limited to this, through hole (H) having a shape such as a polygon or ellipse may also be employed. Can be.

The n-side and p-side electrodes 26a and 26b function as electrodes for electrical connection of the device. In this case, the n-side and p-side electrodes 26a and 26b are generally made of Au or an alloy containing Au. The n-side and p-side electrodes 26a and 26b may be formed by a deposition method or a sputtering process, which is a conventional metal layer growth method.

Hereinafter, another embodiment of the present invention will be described with reference to FIGS. 3 and 4.

3 is a cross-sectional view illustrating a semiconductor light emitting device according to another embodiment of the present invention, and FIG. 4 illustrates a path in which light is emitted to the outside in the semiconductor light emitting device.

First, referring to FIG. 3, the semiconductor light emitting device 30 according to the present embodiment has a sapphire substrate 31, an n-type semiconductor layer 32, an active layer 33, and a p-type semiconductor layer, similarly to the case of FIG. 2. 34, a transparent electrode layer 35, and n-side and p-side electrodes 36a and 36b.

In the case of the present embodiment, the difference from the case of Figure 2 is that the size of the through-hole (H) may vary depending on the stacking direction, the description of the other components can be replaced by the above-described details, through the following Only the description of the hole (H) size change will be described.

As shown in FIG. 3, the size of the through hole H varies in the thickness direction of the sapphire substrate 31, that is, in the stacking direction of the light emitting structure. Specifically, holes formed in the sapphire substrate 31 become smaller in size from the lower surface of the sapphire substrate 31 to the n-type semiconductor layer 32, and holes formed in the light emitting structure are formed in the n-type semiconductor layer 32. The size becomes larger toward the p-type semiconductor layer 34.

As a method of forming a hole in the sapphire substrate 31, a laser or a mechanical method can be generally used. In particular, in the case of forming a hole using a laser, as shown in FIG. 3, the size of the hole may be changed in the thickness direction of the sapphire substrate 31 due to the characteristics of the process.

In addition, the size of the hole in the light emitting structure increases along the stacking direction because the light emitting structure and nitride semiconductor single crystal grown around the hole of the sapphire substrate 31 form a crystal plane according to the crystallographic structure. have. That is, in the case of GaN having a wurtzite crystal structure, the {10-1-1} plane has a high strain energy and a Ga-shaped (incorporation) is reduced compared to the growth plane (0001) surface. Will grow.

As shown in FIG. 4, in the semiconductor light emitting device 30 of the present embodiment, the number of cases in which the light emitted from the active layer 33 can be emitted to the outside is greater than that in the related art, and thus, the luminous efficiency can be improved. have.

That is, if the through hole H is not formed, the light reflected from the interface with the outside and returned to the light emitting structure may be extinguished by resorption, etc. In the present embodiment, the light returned to the light emitting structure is the through hole. The additional interface formed by (H) may be emitted to the outside, and even if not emitted, there may be an opportunity to be reflected again and released to another interface.

In particular, in the present embodiment illustrated in FIGS. 3 and 4, as the size of the through hole H is changed, an effect of increasing the interface area with the outside can be expected.

In the above-described embodiment, the case where the electrode structure of the semiconductor light emitting element is a horizontal structure has been described, but the present invention is not limited thereto. That is, although not shown separately, it will be apparent to those skilled in the art that the hole structure employed in the present invention may be employed in a vertical structure in which n-side and p-side electrodes are formed in different directions of the light emitting structure.

The present invention is not limited by the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

21: sapphire substrate 22: n-type semiconductor layer

23: active layer 24: p-type semiconductor layer

25: transparent electrode layers 26a, 26b: n-side and p-side electrodes

H: through hole

Claims

Board;

A light emitting structure in which a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer are sequentially stacked on the substrate;

At least one through hole formed in the stacking direction to penetrate the light emitting structure; And

First and second electrodes formed to be electrically connected to the first and second conductive semiconductor layers, respectively;

Semiconductor light emitting device comprising a.

The method of claim 1,

And the through hole extends to pass through the substrate.

The method of claim 2,

The through hole formed in the substrate is smaller in size toward the first conductive semiconductor layer, characterized in that the semiconductor light emitting device.

The method of claim 1,

The through hole formed in the light emitting structure is larger in size toward the second conductive semiconductor layer from the first conductive semiconductor layer, characterized in that the semiconductor light emitting device.

The method of claim 1,

The size of the through hole is a semiconductor light emitting device, characterized in that 3 ~ 30㎛.

The method of claim 1,

The through hole is a semiconductor light emitting device, characterized in that the circular shape.

The method of claim 1,

And the first conductive semiconductor layer is an n-type semiconductor layer, and the second conductive semiconductor layer is a p-type semiconductor layer.

The method of claim 1,

And a transparent electrode layer formed on the second conductive semiconductor layer.

The method of claim 8,

And the through hole extends to pass through the transparent electrode layer.

The method of claim 8,

And the first electrode is formed in a region where the active layer is not formed on an upper surface of the first conductive semiconductor layer, and the second electrode is formed on the transparent electrode layer.

The method of claim 1,

The substrate is a conductive substrate, the first electrode is formed on the lower surface of the conductive substrate and the second electrode is a semiconductor light emitting device, characterized in that formed on the upper surface of the second conductive semiconductor layer.

The method of claim 11,

And the first conductive semiconductor layer is a p-type semiconductor layer, and the second conductive semiconductor layer is an n-type semiconductor layer.