KR20130017649A - Light emmitting device - Google Patents

Abstract

The light emitting device according to the embodiment, the substrate; A first semiconductor layer on the substrate; An electron confinement layer formed in the first semiconductor layer to confine electrons transferred from the first semiconductor layer; An active layer formed on the first semiconductor layer; And a second semiconductor layer on the active layer.

Description

Light Emitting Device

An embodiment relates to a light emitting element.

Light emitting diodes (LEDs) are semiconductor devices that convert electrical energy into light. Light emitting diodes have the advantages of low power consumption, semi-permanent life, fast response speed, stability and environmental friendliness compared to conventional light sources such as fluorescent and incandescent lamps. Therefore, a lot of researches are being actively conducted to replace the existing light source with a light emitting diode. Light emitting diodes are increasingly being used as light sources of liquid crystal display devices, light sources of electronic signs, and light sources of lighting devices such as various lamps and street lamps.

In order to increase the marketability of the light emitting diode, it is necessary to increase the luminous efficiency. Therefore, various techniques for increasing the luminous efficiency have recently been proposed.

The embodiment provides a light emitting device having high luminous efficiency.

The embodiment provides a light emitting device with low power consumption.

The light emitting device according to the embodiment, the substrate; A first semiconductor layer on the substrate; An electron confinement layer formed in the first semiconductor layer to confine electrons transferred from the first semiconductor layer; An active layer formed on the first semiconductor layer; And a second semiconductor layer on the active layer.

The light emitting device according to the embodiment includes an electron binding layer to increase luminous efficiency.

The light emitting device according to the embodiment includes an electron binding layer to reduce power consumption.

1 is a cross-sectional view of a light emitting device according to the first embodiment.
2 is a cross-sectional view of a light emitting device according to a second embodiment.
3 is a cross-sectional view of a light emitting device according to a third embodiment.
4 is a table obtained by dividing an example of experiments according to the degree of doping of the electron flux layer of the light emitting device according to the first embodiment.
5 is a table showing experimental results according to each experimental example.

In the description of an embodiment, each layer (film), region, pattern, or structure is formed “on” or “under” a substrate, each layer (film), region, pad, or pattern. In the case where it is described as "to", "on" and "under" include both "directly" or "indirectly" formed. Also, the criteria for top, bottom, or bottom of each layer will be described with reference to the drawings.

Hereinafter, embodiments will be described with reference to the accompanying drawings. The thickness and size of each layer in the drawings are exaggerated, omitted, or schematically shown for convenience and clarity of explanation. In addition, the size of each component does not entirely reflect the actual size.

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

Referring to FIG. 1, the light emitting device according to the first embodiment may include a substrate 100, a buffer layer 103 on the substrate 100, an undoped semiconductor layer 105, a first semiconductor layer 110, and an active layer 130. ), The second semiconductor layer 240, and the transparent electrode layer 150 may be sequentially stacked, and may include the electron binding layer 120 inserted in the middle of the first semiconductor layer 110. The first electrode 170 may be formed on a portion of the first semiconductor layer 110. The second electrode 160 may be formed on the transparent electrode layer 150.

The substrate 100 may be formed of, for example, at least one of single crystal, SiC, GaAs, GaN, ZnO, Si, GaP, InP, and Ge, but is not limited thereto.

In order to promote growth of a layer stacked on the substrate 100 and to improve luminous efficiency of the light emitting device, a predetermined pattern or a slope may be formed on the upper surface of the substrate 100, but is not limited thereto.

The buffer layer 103 and the undoped semiconductor layer 105 may be stacked on an upper surface of the substrate 100. Having the composition formula of the buffer layer 103 and the undoped semiconductor layer 105 is _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1) Semiconductor material, for example, InAlGaN, GaN, AlGaN, AlInN, InGaN, AlN, InN, or the like. The buffer layer 103 and the undoped semiconductor layer 105 may have a significantly lower electrical conductivity than the first and second conductivity type semiconductor layers 112 and 116 because the conductive dopant is not doped. The buffer layer 103 is used to mitigate the lattice mismatch between the semiconductor layers to be formed thereon and the substrate 100. The buffer layer 103 may be formed by Metal Organic Chemical Vapor Deposition (MOCVD) or Vapor-Phase Epitaxy (VPE).

The first semiconductor layer 110 may be stacked on the undoped semiconductor layer 105. The first semiconductor layer 100 may be an n-type semiconductor layer including an n-type dopant. The n-type semiconductor layer may be selected from a semiconductor material having a compositional formula of Al _x Ga _{1 - x} N (0 ≦ _x ≦ 1), for example, GaN, AlN, AlGaN, and the like, and n-type such as Si, Ge, Sn, or the like. Dopants may be doped.

The first semiconductor layer 110 may include a first region 113, a second region 115, and a third region 117.

In the first region 113, an n-type dopant may be heavily doped. The first region 113 may be doped with an n-type dopant at a concentration of 10 ²¹ to 10 ²² atoms / cm 3. In the second region 115, n-type dopants may be doped at a lower concentration than the first region 113. The second region 115 may be doped at a concentration of 10 ¹⁷ to 10 ¹⁸ atoms / cm 3. The third region 117 may have a higher doping concentration than the second region 115 and a lower doping concentration than the first region 113. The third region 117 may be doped at a concentration of 10 ¹⁹ to 10 ²¹ atoms / cm 3. The higher the doping concentration, the stronger the conductivity of the semiconductor layer.

The electron binding layer 120 may be formed between the first region 113 and the second region 115. The electron binding layer 120 may be an n-type semiconductor layer including an n-type dopant. The electron binding layer 120 may be formed of a material having a composition formula of GaxIn (1-x) N (0 <x <1).

The first semiconductor layer 110 may be formed by metal organic chemical vapor deposition (MOCVD) or vapor-phase epitaxy (VPE).

Since the electron binding layer 120 includes In (Indium), the energy band gap is reduced compared to the first semiconductor layer 110, and thus, the first electrode 170 and the first region ( Electrons introduced through the 113 are accumulated in the electron binding layer 120. As the electrons are accumulated in the electron binding layer 120, electrons are evenly distributed on the front of the electron binding layer 120. Then, when the electrons are introduced into the active layer 130, the electrons are widely introduced and as a result, in the active layer 130. Luminous efficiency increases with front emission.

The electron binding layer 120 may be formed of a super lattice having a heterogeneous junction periodically. The period of the superlattice structure may be formed from 1 cycle to 20 cycles. The electron-bonding layer may be formed to a thickness between 1 kPa and 200 kPa. The electron binding layer 120 may be formed of a superlattice structure of n-type InGaN / InGaN. The electron binding layer 120 may be formed of a superlattice structure of n-type InGaN / InGaN having different In contents and the same Si content. The electron-bonding layer 120 may have a superlattice structure of n-type InGaN / InGaN having the same In content and different Si content. The electron thin film layer 120 may be formed of a superlattice structure of n-type InGaN / InGaN having different In contents and Si contents. The electron binding layer 120 may be formed in a structure in which one layer of InGaN / InGaN is not doped with Si.

The active layer 130 may be formed on the first semiconductor layer 110. The active layer 130 may be formed in a quantum well structure. When the active layer 130 has a quantum well structure, for example, a well layer having a composition formula of InxAlyGa1-yN (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) and InaAlbGa1-a-bN It may have a single or quantum well structure having a barrier layer having a compositional formula of (0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ a + b ≦ 1). The well layer may be formed of a material having an energy band gap lower than the energy band gap of the barrier layer.

The active layer 130 may generate light by energy generated during recombination of electrons and holes provided from the first semiconductor layer 110 and the second semiconductor layer 140.

The second semiconductor layer 140 may be formed on the active layer 130. The second semiconductor layer 140 may be a semiconductor film (for example, a p-GaN layer) having a p-type conductivity. According to an embodiment of the present invention, the second semiconductor layer 140 may be a magnesium-doped GaN film (Mg-doped GaN). The second semiconductor layer 14 may be formed by Metal Organic Chemical Vapor Deposition (MOCVD) or Vapor-Phase Epitaxy (VPE).

The transparent electrode layer 150 may be formed on the second semiconductor layer 140. The transparent electrode layer 150 may prevent current from being biased around the second electrode 170 by spraying a current.

The translucent electrode layer 150 may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO), and indium gallium tin (IGTO). oxide), aluminum zinc oxide (AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), IrOx, RuOx, Ni, Ag or Au using one or more can be implemented in a single layer or multiple layers.

The second electrode 160 may be formed in a portion of the light transmissive electrode layer 150. For example, the first electrode 170 and the second electrode 160 may be formed in a single layer or a multilayer structure including at least one of AU, Al, Ag, Ti, Cu, Ni, or Cr. It is not limited

Referring to the operation principle of the light emitting device, electrons introduced through the first electrode 170 are introduced into the electron binding layer 120 through the first region 113. The electrons are stacked in the electron flux layer 120 having a narrow energy band gap and spread to a wide area, and then the electrons flow into the second area 115. Electrons introduced into the second region 115 are spread more widely by the second region 115 having a relatively low conductivity, and are then provided to the active layer 130 through the third region 117 to provide the first agent. Light is generated by recombination with holes provided to the active layer 130 through the second electrode 160 and the second semiconductor layer 140.

2 is a cross-sectional view of a light emitting device according to a second embodiment.

2, the light emitting device according to the second embodiment includes a substrate 200, a buffer layer 203 on the substrate 200, an undoped semiconductor layer 205, a first semiconductor layer 210, and an active layer 230. In addition, the second semiconductor layer 240 and the transparent electrode layer 250 may have a stacked structure, and may include an electron binding layer 220 inserted in the middle of the first semiconductor layer 210. The first electrode 270 may be formed on a portion of the first semiconductor layer 210, and the second electrode 260 may be formed on the transparent electrode layer 250.

Compared to the first embodiment, the second embodiment differs only in the position of the electron flux layer 220, and the rest of the configuration is almost the same. Therefore, in the description of the second embodiment, detailed description of the same parts as in the first embodiment will be omitted.

The first semiconductor layer 210 may include a first region 213, a second region 215, and a third region 217.

In the first region 213, an n-type dopant may be heavily doped. The first region 213 may be doped with an n-type dopant at a concentration of 10 ²¹ to 10 ²² atoms / cm 3. In the second region 215, n-type dopants may be doped at a lower concentration than the first region 213. The second region 215 may be doped at a concentration of 10 ¹⁷ to 10 ¹⁸ atoms / cm 3. The third region 217 may have a higher doping concentration than the second region 215, and may have a lower doping concentration than or equal to the first region 213. The third region 217 may be doped at a concentration of 10 ¹⁹ to 10 ²¹ atoms / cm 3. The higher the doping concentration, the stronger the conductivity of the semiconductor layer.

The electron confinement layer 220 may be formed between the first region 213. The electron confinement layer 220 may be an n-type semiconductor layer including an n-type dopant. The electron binding layer 220 may be formed of a material having a composition formula of GaxIn (1-x) N (0 <x <1).

Since the electron binding layer 220 includes In (Indium), the energy band gap is reduced compared to the first semiconductor layer 210, and thus, the first electrode 270 and the first region ( Electrons introduced through the 213 are accumulated in the electron binding layer 220. As the electrons are accumulated in the electron binding layer 220, the electrons are evenly distributed on the entire surface of the electron binding layer 220, and when the electrons are introduced into the active layer 230, the electrons are widely introduced and as a result, in the active layer 230. Luminous efficiency increases with front emission.

The electron binding layer 120 may be formed of a super lattice having a heterogeneous junction periodically.

Referring to the operation principle of the light emitting device according to the second embodiment, electrons introduced through the first electrode 270 are introduced into the electron binding layer 220 through the first region 213. The electrons are stacked in the electron flux layer 220 having a narrow energy band gap and spread to a wide area, and then flow through the upper part of the first area 213 to the second area 215. Electrons introduced into the second region are spread more widely by the second region 215 having a relatively low conductivity and then provided to the active layer 230 through the third region 217 to provide the second electrode 260. ) And light is generated by recombination with holes provided to the active layer 230 through the second semiconductor layer 240.

The difference between the first embodiment and the second embodiment is the difference of the position of the electron-bonding layer in the first semiconductor layer, and the position of the electron-bonding layer is not limited to the first and second embodiments but is defined in any one of the first semiconductor layers. Even if the position is located, the electrons are stacked and dispersed in a wide area to increase the luminous efficiency.

3 is a cross-sectional view of a light emitting device according to a third embodiment.

Referring to FIG. 3, the light emitting device according to the third embodiment may include a substrate 300, a buffer layer 303 on the substrate 300, an undoped semiconductor layer 305, a first semiconductor layer 310, and a superlattice layer ( 380, the second semiconductor layer 340, and the transmissive electrode layer 350 are sequentially stacked, and the electron thin layer 320 interposed between the first semiconductor layer 310 and the superlattice layer 380. It may include. The first electrode 370 may be formed on a portion of the first semiconductor layer 310, and the second electrode 360 may be formed on the transparent electrode layer.

Compared to the first embodiment, the third embodiment has almost the same configuration except that a superlattice layer is formed between the active layer and the electron flux layer. Therefore, in the description of the third embodiment, detailed description of the same parts as in the first embodiment will be omitted.

The superlattice layer 380 is formed of a super lattice with a heterogeneous junction periodically. The superlattice layer 380 may be formed by periodically alternating materials having different energy levels. The superlattice layer 380 may be formed by varying the doping level of the same material.

The electron binding layer 320 may be inserted between the first semiconductor layer 310 and the superlattice layer 380. The electron confinement layer 320 may be an n-type semiconductor layer including an n-type dopant. The electron binding layer 320 may be formed of a material having a composition formula of GaxIn (1-x) N (0 <x <1).

Since the electron binding layer 320 includes In (Indium), the energy band gap is reduced as compared with the first semiconductor layer 310, and thus the first electrode 370 and the first semiconductor layer are reduced. Electrons introduced through the 310 are accumulated in the electron binding layer 320. As the electrons are accumulated in the electron binding layer 320, electrons are evenly distributed on the front surface of the electron binding layer 320, and when the electrons are introduced into the active layer 330, the electrons are widely introduced, and as a result, in the active layer 330 Luminous efficiency increases with front emission.

The electron binding layer 320 may be formed of a super lattice having a heterogeneous junction periodically.

Referring to the operation principle of the light emitting device according to the third embodiment, the electrons introduced through the first electrode 370 flow into the electron flux layer 320 through the first semiconductor layer 310. The electrons are stacked on the electron flux layer 320 having a narrow energy band gap and spread to a wide area, and are then provided to the active layer 330 through the superlattice layer 380 to provide the second electrode 360. And light is generated by recombination with holes provided to the active layer 330 through the second semiconductor layer 340.

Although not illustrated, the first semiconductor layer 310 may include a first region, a second region, and a third region.

The first region may be heavily doped with an n-type dopant. The first region may be doped with an n-type dopant at a concentration of 10 ²¹ to 10 ²² atoms / cm 3. The second region may be doped with an n-type dopant at a lower concentration than the first region. The second region may be doped at a concentration of 10 ¹⁷ to 10 ¹⁸ atoms / cm 3. The third region may have a higher doping concentration than the second region and a lower doping concentration than the first region. The third region may be doped at a concentration of 10 ¹⁹ to 10 ²¹ atoms / cm 3. The higher the doping concentration, the stronger the conductivity of the semiconductor layer. As described in the first and second embodiments, the second region spreads electrons with low conductivity.

In addition, in the case where the first semiconductor layer includes the first to third regions, the electron-bonding layer has an effect of increasing the luminous efficiency by stacking electrons and dispersing the electrons into a wide region, even if located anywhere in the first semiconductor layer.

4 and 5 are tables showing experimental results of the first embodiment.

4 is a table showing a test example according to the degree of doping of the electron-bonding layer of the light emitting device according to the first embodiment, Figure 5 is a table showing the test results according to each test example.

4 and 5, the first to fourth experimental examples change the doping degree with the electron-bonding layer as in the first embodiment, and the reference is the test result when there is no electron-bonding layer.

The thickness of the electron-bonding layer in the first to fourth experimental examples is fixed at 50 kPa.

The degree of doping in the first to fourth experimental examples is based on the doping concentration in the first region of the first embodiment. When the doping concentration of the first region is referred to as C _Si , the doping concentration of the electron bonding layer of the first experimental example is 0.3C _Si and has a concentration of 30% of the first region, and the doping of the electron bonding layer of the second experimental example. The concentration was 0.53C _Si and the concentration of 53% of the first region, the doping concentration of the electron binding layer of the third experimental example was 0.75C _Si had a concentration of 75% of the first region, the electron of the fourth experimental example The doping concentration of the confinement layer is doped with C _{Si so} as to have the same concentration as the doping concentration of the first region.

In FIG. 5, forward voltages (VF), threshold voltages (VT), reverse currents (IR), reverse voltages (VR), and peak wavelengths of the first to fourth experimental examples are illustrated. (peak wavelength, WP), dominant wavelength (WD), full width at half maximum (WH), and optical power (power, PO) were measured, respectively.

It can be seen that the optical power PO of the first to fourth embodiments is higher than that of the reference not including the electron-bonding layer. In particular, in the third embodiment, since the optical power of 16.69mW is measured at 20mA, it can be seen that the optical power of 10% is increased compared to the standard 15.17mW.

The increase in the optical power has the effect of increasing the luminous efficiency and reducing the power consumption.

In addition, the features, structures, effects, and the like described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments can be combined and modified by other persons having ordinary skill in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

Although the above description has been made 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 are not illustrated above without departing from the essential characteristics of the present embodiments. It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiments 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.

100,200,300: substrate 103,203,303: buffer layer
105,205,305: undoped semiconductor layer 110,210,310: first semiconductor layer
113,213,313: first area 115,215,315: second area
117,217,317: third region 120,220,320: electron binding layer
130, 230, 330: active layer 140, 240, 340: second semiconductor layer
150, 250, 350: transparent electrode layer 160, 260, 360: second electrode
170,270,370: first electrode 380: superlattice layer

Claims (12)

Board;
A first semiconductor layer on the substrate;
An electron confinement layer formed in the first semiconductor layer to confine electrons transferred from the first semiconductor layer;
An active layer formed on the first semiconductor layer; And
A light emitting device comprising a second semiconductor layer on the active layer. The method of claim 1,
Wherein the first semiconductor layer comprises a first semiconductor layer,
A heavily doped first region;
A lightly doped second region; And
And a third region doped at a level between the first region and the second region. The method of claim 2,
The electron binding layer is positioned between the first region and the second region. The method of claim 2,
The electron binding layer is positioned in the first region. The method of claim 1,
The electron binding layer is a light emitting device formed of a super lattice structure. The method of claim 5,
The electron binding layer is a light emitting device formed of a superlattice structure of n-type InGaN / InGaN. The method of claim 1,
The electron binding layer is formed of a material having a composition of Ga x In (1-x) N (0 <x <1). The method of claim 1,
And a superlattice layer formed between the active layer and the first semiconductor layer. 9. The method of claim 8,
The electron binding layer is positioned in a contact area under the superlattice layer. The method of claim 1,
The electron binding layer has a thickness of between 1 Å to 200 Å. The method of claim 2,
The doping concentration of the electron binding layer is a light emitting device of 53% to 75% of the first region. The method of claim 1,
The electron binding layer has a narrower energy band gap than the first semiconductor layer.

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