KR20160057664A - High efficiency light emitting device - Google Patents

High efficiency light emitting device Download PDF

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KR20160057664A
KR20160057664A KR1020140158544A KR20140158544A KR20160057664A KR 20160057664 A KR20160057664 A KR 20160057664A KR 1020140158544 A KR1020140158544 A KR 1020140158544A KR 20140158544 A KR20140158544 A KR 20140158544A KR 20160057664 A KR20160057664 A KR 20160057664A
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layer
doping
doped
concentration
dopant
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Korean (ko)
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문수영
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서울바이오시스 주식회사
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/025—Physical imperfections, e.g. particular concentration or distribution of impurities
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/04—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction
    • H01L33/06—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/26—Materials of the light emitting region
    • H01L33/30—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table
    • H01L33/32—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table containing nitrogen

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Abstract

A light emitting device is disclosed. The light emitting device includes an n-type nitride based contact layer including an Si dopant; a Ge doping layer located on the n-type nitride based contact layer and comprising a Ge dopant; An active layer located on the Ge doping layer; And the p-type nitride based semiconductor layer located on the active layer, wherein the Ge doping layer has a thickness within a range of 10 to 100 nm, and the electron concentration of the Ge doping layer is higher than the electron concentration of the n-type nitride based contact layer.

Description

[0001] HIGH EFFICIENCY LIGHT EMITTING DEVICE [0002]

The present invention relates to a light emitting device, and more particularly to a light emitting device having high efficiency and high reliability.

BACKGROUND ART [0002] Recently, nitride semiconductors widely used as base materials for light emitting devices such as light emitting diodes are grown by using a same substrate such as a gallium nitride substrate or a different substrate such as sapphire. Some of the factors affecting the crystallinity and luminous efficiency of these nitride-based semiconductors are influenced by the properties of the growth substrate.

For example, a nitride-based semiconductor formed by growing a heterogeneous substrate as a growth substrate has a high defect density due to a difference in lattice constant and a difference in thermal expansion coefficient between a growth substrate and a nitride-based semiconductor. Particularly, nitride-based semiconductors grown on a heterogeneous substrate suffer from stress and strain due to the difference in lattice constant, resulting in piezo-electric polarization inside. Furthermore, the nitride-based semiconductor grown on the growth substrate having the C plane as a growth plane grows in a (normal) direction to the C plane, and spontaneous polarization exists therein. Due to the piezoelectric polarization and the polarization due to the spontaneous polarization, the energy band of the nitride-based semiconductor is bent, which causes the distribution of holes and electrons in the active layer to be separated. As a result, the efficiency of recombination of electrons and electrons decreases, resulting in a lower luminous efficiency, a red shift phenomenon of light emission, and an increase in the forward voltage (V f ) of the light emitting device.

On the other hand, the doping concentration of the N-type and P-type semiconductor layers can be relatively increased in order to alleviate the lowering of the luminous efficiency by separating the distribution of holes and electrons. When the nitride-based semiconductor is doped at a relatively high concentration, the piezo-electric field is weakened, and the warping of the energy band is mitigated. However, the increase of the doping concentration is equivalent to the increase of the concentration of the impurity, which deteriorates the crystallinity of the nitride-based semiconductor, thereby decreasing the internal quantum efficiency and weakening the resistance to breakage of the light emitting device by the electrostatic discharge.

A problem to be solved by the present invention is to provide a light emitting device having a high efficiency and a high reliability by lowering the piezoelectric polarization without deteriorating the crystallinity of the semiconductor layer of the light emitting element.

A light emitting device according to an aspect of the present invention includes: an n-type nitride based contact layer including a Si dopant; A Ge doping layer positioned on the n-type nitride based contact layer and including a Ge dopant; An active layer located on the Ge doping layer; And a p-type nitride based semiconductor layer disposed on the active layer, wherein the Ge doping layer has a thickness within a range of 10 to 100 nm, and the electron concentration of the Ge doping layer is less than the electron concentration of the n-type nitride based contact layer high.

Accordingly, the Ge dopant is doped at a high concentration to improve the electron injection efficiency in the active layer of the light emitting device, thereby increasing the light emitting efficiency. In addition, even if doped at a high concentration, the crystallinity of the active layer of the light emitting element can be maintained without deteriorating.

The Ge doping layer may further include an Si dopant.

The Ge doping layer may have a thickness of 5 x 10 18 atoms / cm 3 to 8 x 10 20 atoms / cm 3 Lt; RTI ID = 0.0 > Ge < / RTI >

Further, the Ge doping layer may have a thickness of 1 x 10 19 atoms / cm 3 to 2 x 10 20 atoms / cm 3 Lt; RTI ID = 0.0 > Ge < / RTI >

The light emitting device may further include a lightly doped layer positioned below the Ge doping layer, and the lightly doped layer may include an n-type dopant having a lower concentration than the Ge doping layer.

The Ge doping layer and the lightly doped layer may be repeatedly laminated at least twice to form a superlattice structure.

In addition, the lightly doped layer may be modulated and doped.

Also, the Ge doping layer may be doped with Ge.

In some embodiments, the light emitting device may further include a second Ge doping layer located at the lower end of the lightly doped layer and including a Ge dopant, And may include a high concentration of n-type dopant.

The lightly doped layer may be modulated and doped.

Also, the Ge doping layer may be doped with Ge.

The light emitting device may further include a super lattice layer disposed between the n-type nitride-based contact layer and the Ge doping layer and having two or more layers having different composition ratios and having one or more layers stacked.

The Ge dopant concentration in the Ge doping layer may be higher than the Si dopant concentration in the Ge doping layer.

In some embodiments, the Ge doping layer may comprise at least one of GaN, AlGaN, InGaN, and AlInGaN, wherein the mole fraction of Ga in each of AlGaN, InGaN and AlInGaN is in the range of mole fractions of Al and / or In .

The active layer may include a multiple quantum well structure in which a barrier layer and a well layer are repeatedly stacked, and the barrier layer may include a Ge-doped layer.

Further, the barrier layer may include low concentration doping layers located above and below the Ge doped layer, and the low concentration doping layer may include a Ge dopant at a lower concentration than the Ge doped layer of the barrier layer, Or undoped.

According to the present invention, a heavily doped Ge-doped Ge layer is located below the active layer, thereby improving the electron injection efficiency of the active layer and improving the luminous efficiency of the light emitting device. Further, since Ge is doped in the Ge doping layer at a relatively high concentration, a light emitting device having improved resistance to electrostatic discharge can be provided.

1 is a cross-sectional view illustrating a light emitting device according to an embodiment of the present invention.
2A and 2B are enlarged cross-sectional views illustrating a structure of a Ge doping layer according to embodiments of the present invention.
3A and 3B are enlarged cross-sectional views illustrating the structure of an active layer according to embodiments of the present invention.
4A and 4B are cross-sectional views illustrating a light emitting device according to another embodiment of the present invention.
5 is a cross-sectional view illustrating a light emitting device according to another embodiment of the present invention.
6 is a cross-sectional view illustrating a light emitting device according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so that those skilled in the art can sufficiently convey the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the width, length, thickness, etc. of components may be exaggerated for convenience. It is also to be understood that when an element is referred to as being "above" or "above" another element, But also includes the case where there are other components in between. Like reference numerals designate like elements throughout the specification.

The respective composition ratios, growth methods, growth conditions, thicknesses, and the like for the nitride-based semiconductor layers described below are examples, and the present invention is not limited to the following examples. For example, when expressed by AlGaN, the composition ratio of Al and Ga can be variously applied according to the needs of a person having ordinary skill in the art (hereinafter, "a typical technician"). The nitride-based semiconductor layers described below may be grown using various methods commonly known to those skilled in the art. For example, metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or hydride Vapor Phase Epitaxy) and the like. However, in the embodiments described below, it is described that the semiconductor layers are grown in the growth chamber using MOCVD. In the growth process of the nitride-based semiconductor layers, sources introduced into the growth chamber may use sources known to those skilled in the art. For example, TMGa and TEGa may be used as the Ga source, and TMAl and TEAl TMIn, TEIn, etc. may be used as the In source, and NH 3 may be used as the N source. However, the present invention is not limited thereto.

Also, in the embodiments disclosed below, the degree of doping, which is defined as 'high doping' and 'low doping', is relative and is not limited to a specific value above or below a specific value. In addition, 'low concentration doping' described herein includes not only doping at a relatively low concentration but also undoped without containing a dopant.

FIGS. 1A and 1B are cross-sectional views illustrating a light emitting device according to an embodiment of the present invention, FIGS. 2A and 2B are enlarged cross-sectional views illustrating a structure of a Ge doping layer according to embodiments of the present invention, FIG. 3B is an enlarged cross-sectional view illustrating a structure of an active layer according to embodiments of the present invention. FIG.

1, a light emitting device 100 according to an embodiment of the present invention includes an n-type nitride based contact layer 130, a Ge doping layer 160, an active layer 170, and a p-type nitride based semiconductor layer 180 ). Further, the light emitting device 100 may further include a growth substrate 110, a nitride-based undoped layer 120, and a superlattice layer 150.

The growth substrate 110 is not limited as long as it can grow the nitride based semiconductor layer, and may be an insulating or conductive substrate. The growth substrate 110 may be, for example, a sapphire substrate, a silicon substrate, a silicon carbide substrate, an aluminum nitride substrate, or a gallium nitride substrate. In addition, the growth substrate 110 may include a growth surface on which the nitride based semiconductor layer is grown, and the growth surface may be a crystal surface having characteristics of polarity, non-polarity, or anti-polarity. Therefore, the nitride-based semiconductor layer grown on the growth substrate 110 may have a polar growth plane such as a c-plane, a non-polar growth plane such as an a-plane or an m-plane, or a non- Lt; / RTI >

The nitride-based undoped layer 120 may be positioned on the growth substrate 110 and may include a nitride semiconductor such as (Al, Ga, In) N. For example, the nitride-based undoped layer 120 may comprise u-GaN. The nitride-based undoped layer 120 does not contain impurities such as Si or Mg, and can have a relatively good crystallinity. Accordingly, the crystallinity of the other semiconductor layers located on the nitride-based on-pattern layer 120, which will be described later, can be improved.

However, the growth substrate 110 and the nitride-based on-pattern layer 120 may be omitted depending on the type of the light emitting device. When the light emitting device 100 according to the present embodiment is applied to a flip chip type light emitting device or a vertical type light emitting device, the growth substrate 110 can be removed, and the nitride based on p layer 120 Can be removed together with the growth substrate 110.

On the other hand, a buffer layer (not shown) may be interposed between the nitride-based undoped layer 120 and the growth substrate 110.

The buffer layer may include AlGaN and / or GaN, and may be grown on the growth substrate 110 at a temperature of about 500 to 600 ° C. The buffer layer can serve as a nucleus layer in which the nitride-based semiconductor can grow when the growth substrate 110 is a substrate different from the nitride-based semiconductor, and the nitride-based semiconductor grown on the buffer layer and the growth substrate 110 It may also serve to mitigate stress and strain due to lattice mismatch.

The n-type nitride-based contact layer 130 may include a nitride-based semiconductor such as (Al, Ga, In) N, and may further include a dopant such as Si, Ge, or Te to have an n- . In particular, the n-type nitride based contact layer 130 may include Si as a dopant. Si may be contained in the n-type nitride-based contact layer 130 at a concentration of 1 x 10 17 atoms / cm 3 or more and 5 x 10 19 atoms / cm 3 or less. The n-type nitride based contact layer 130 may have a thickness of several micrometers and may be composed of a single layer or multiple layers.

For example, the n-type nitride based contact layer 130 may be formed by introducing into the growth chamber a Group III atom source such as Al, Ga, In, etc., a Group V atom source such as N, and a Si dopant source such as Silane It can be grown. At this time, growing Si with a dopant is superior to application of Te or Ge to a dopant. Accordingly, the n-type nitride-based contact layer 130 is grown so as to include Si as a dopant, so that the growth process of the n-type nitride-based contact layer 130 can be performed relatively easily.

Since the n-type nitride-based contact layer 130 contains Si at a concentration of not less than 1 x 10 17 atoms / cm 3 and not more than 5 x 10 19 atoms / cm 3 , the crystallinity is not significantly deteriorated by the Si dopant. Accordingly, the n-type nitride-based contact layer 130 can maintain relatively good crystallinity even when it contains Si rather than Ge as a dopant.

However, the present invention is not limited thereto, and the n-type nitride based contact layer 130 may include Ge and / or Te as an n-type dopant.

The superlattice layer 150 may be located on the n-type nitride based contact layer 130. The superlattice layer 150 may include a structure in which two-component to four-component nitride-based semiconductor layers including a nitride-based semiconductor such as (Al, Ga, In) N are stacked. At this time, each of the layers stacked in the superlattice layer 150 may have a thickness of several to several tens of nanometers. Further, the stacked structure may include a structure in which two or more layers are repeatedly stacked. For example, the superlattice layer 150 may include a structure in which a GaN layer and an InGaN layer are repeatedly stacked, a structure in which a GaN layer and an AlInGaN layer are repeatedly stacked, and the like.

Since the superlattice layer 150 includes a structure in which nitride-based semiconductor layers having different compositions are stacked, stress and strain due to lattice mismatching can be alleviated, and defects such as dislocations can propagate along the growth direction of the semiconductor layer To the semiconductor layers to be grown. In particular, the superlattice layer 150 is disposed under the active layer 170, thereby improving the crystallinity of the active layer 170. [

The Ge doping layer 160 may be located on the superlattice layer 150 and may also be located below the active layer 170. In particular, the Ge doping layer 160 may be located directly below the active layer 170. The Ge doping layer 160 may include a nitride based semiconductor such as GaN, AlGaN, InGaN, or AlInGaN containing (Al, Ga, In) N, and may include GaN in particular. In addition, when the Ge doping layer 160 contains AlGaN, InGaN, or AlInGaN, the mole fraction of Ga may be higher than the mole fraction of Al and / or In. The Ge doping layer 160 can be grown by introducing a Group III atom source such as Al, Ga, In, etc., a Group V atom source such as N, and a Ge dopant atom source into the growth chamber. At this time, IBGe (Isobutylgermane) may be used as a Ge dopant atom source, but the present invention is not limited thereto.

The Ge doping layer 160 may include a relatively high concentration of electrons. Specifically, the electron concentration of the Ge doping layer 160 may be higher than the electron concentration of the n-type nitride based contact layer 130. In other words, the Ge doping layer 160 may include electrons of relatively high density.

The Ge doping layer 160 may include a nitride-based semiconductor layer containing Ge as a dopant, and may include, for example, 5 x 10 18 atoms / cm 3 to 8 x 10 20 atoms / cm 3 Ge atoms in the concentration range, more preferably 1 x 10 19 atoms / cm 3 to 2 x 10 20 atoms / cm 3 density Based semiconductor layer containing Ge atoms in the range of from 0.1 to 10 mu m. The Ge doping layer 160 may comprise a single layer or multiple layers, and where the Ge doping layer 160 comprises multiple layers, at least some of the layers may comprise Ge as a dopant. The Ge doping layer 160 may serve as an electron injecting layer for supplying electrons to the active layer 170 and may include a relatively high concentration of Ge atoms as described above so that a large amount of electrons are injected into the active layer 170 Can supply. Therefore, the electron concentration in the active layer 170 can be increased to improve the luminous efficiency of the luminous means 100. [

Also, since the Ge doping layer 160 includes a Ge dopant having a relatively high concentration, it is possible to alleviate the bending phenomenon of the energy band due to the piezoelectric polarization inside the light emitting element. Accordingly, the degree of spatial separation of electrons and holes in the active layer 170 can be reduced, and the luminous efficiency of the luminous means 100 can be improved. Further, the forward voltage V f of the light emitting device 100 can be prevented from increasing.

On the other hand, the Ge doping layer 160 can contain Ge as an n-type dopant and can maintain excellent crystallinity and have a relatively low surface roughness as compared with a Si-doped layer containing Si as an n-type dopant. When Si is used as a dopant to form a nitride-based semiconductor into an n-type conductivity, Si is substituted with a site of a group III atom (Ga, Al, In). However, since Si is not an element located at the same cycle as Ga, the diameter of Si atoms is smaller than the diameter of Ga atoms. Therefore, when Si is doped to GaN or AlGaN, InGaN, or AlInGaN having a relatively high Ga mole fraction, Si atoms are substituted for one Ga atom site, and the probability of occurrence of a defect due to lattice mismatch is high. In addition, since the size of Si atoms is small, tensile stress is generated in the lattice around the portion substituted with Si, and lattice mismatching or cracking due to stress and strain may occur. In addition, Si has a strong bonding force with N relatively, and there is a high probability that two or more Si atoms are positioned at one Ga atom site. Therefore, the higher the doping concentration of Si, the higher the probability that Si atoms having strong bonding force with N are arranged at one site, thereby deteriorating the crystallinity of the nitride-based semiconductor. As described above, a layer serving as an electron injecting layer requires a high dopant concentration, but there are limitations in increasing the doping concentration of Si owing to such problems that may occur when Si is excessively doped.

For example, when Si is doped to a concentration of 1 x 10 19 atoms / cm 3 or more, a peak having a broad width can be observed in XRD measurement. At this time, the full width at half maximum (FWHM) of the peak may be very large, about 150 arcsec or more. As described above, the surface of the nitride semiconductor containing a relatively high concentration of Si has a rough surface characteristic, and the surface roughness RMS (root mean square) value of the semiconductor layer is very high. In the case of a nitride-based semiconductor containing a relatively high concentration of Si as described above, the crystallinity thereof can be extremely deteriorated. If the Si-doped layer is located below the active layer, the crystallinity of the active layer is deteriorated Reduces the internal quantum efficiency, and weakens the resistance to electrostatic discharge.

On the other hand, Ge is located on the same cycle as Ga, and there is no great difference in the size of the atoms. Therefore, when Ge is used as a dopant in order to form a nitride-based semiconductor into an n-type conductivity, stress and strain induced in the surrounding lattice are very small due to lattice mismatch even when Ge is replaced with a Ga atomic site. Therefore, even if Ge is substituted in the nitride-based semiconductor as a dopant, the degree of deterioration of crystallinity due to lattice mismatch is relatively small, and the probability of occurrence of defects such as cracks is also very low. In addition, Ge is weaker in binding force with N than Si, so that even if Ge is excessively doped, the probability of N atoms attracting a plurality of Ge atoms is low and the probability that two or more Ge atoms are positioned at one Ga atom site is low . Furthermore, Ge atoms are larger in size than Si atoms, and there is a high probability that only one Ge atom exists in one Ga atom site. Therefore, even if the doping concentration of Ge increases, the probability that only one Ge atom is located at one Ga atomic site increases, thereby minimizing the deterioration of the crystallinity of the nitride-based semiconductor. Thus, in the case of a nitride-based semiconductor containing Ge as a dopant, it may contain a relatively high concentration of Ge.

For example, when Ge is doped to a concentration of 1 x 10 19 atoms / cm 3 or more, a peak having a narrow width can be observed in XRD measurement. Further, even when Ge is doped at a concentration of 1 x 10 20 atoms / cm 3 or more, a peak having a narrow width can be observed in XRD measurement. At this time, the half width of the peaks can be observed to be about 50 arcsec or less. In addition, the surface of the nitride-based semiconductor containing Ge at a relatively high concentration has surface characteristics with low roughness. Therefore, the surface roughness RMS (Root Mean Square) of the nitride semiconductor layer including Ge may be relatively low.

That is, Ge is doped at a concentration of about 5 x 10 18 atoms / cm 3 to 8 x 10 20 atoms / cm 3 Concentration, more preferably 1 x 10 19 atoms / cm 3 to 2 x 10 20 atoms / cm 3 The crystallinity of the nitride based semiconductor layer is not deteriorated. Therefore, since the light emitting device 100 includes the Ge doping layer 160 doped with a high concentration, the crystallinity of the active layer 170 can be maintained to be excellent and the internal quantum efficiency can be prevented from being reduced, , The efficiency of injecting electrons from the Ge doping layer 160 into the active layer 170 is improved to increase the internal quantum efficiency and reduce the forward voltage. In addition, the Ge doping layer 160, the active layer 170, and the p-type nitride-based semiconductor layer 180 can be made excellent in crystallinity by the Ge doping layer 160 doped with a high concentration of Ge, The extension of the depletion layer formed in the light emitting device 100 can be suppressed by increasing the internal capacitance of the light emitting device 100 to improve the resistance to electrostatic discharge.

Further, the Ge doping layer 160 may further include Si as a dopant. The Si dopant doped into the Ge doping layer 160 can be doped with a relatively small concentration compared to the Ge dopant and thus the crystallinity of the Ge doping layer 160 deteriorates even though the Ge doping layer 160 includes an Si dopant It does not.

On the other hand, the Ge doping layer 160 may be a single layer or a multilayer. As shown in FIG. 2A, the Ge-doped layer 160 may include a nitride-based semiconductor layer containing Ge as a dopant, and the nitride-based semiconductor layer formed in the form of a single layer may be, for example, Ge-doped A GaN layer, an AlGaN layer, an InGaN layer, or an AlInGaN layer. At this time, the thickness of the Ge doping layer 160 may be 100 nm or less, and further, it may be within the range of 10 to 100 nm. When the thickness of the Ge doping layer 160 is greater than 100 nm, the crystallinity of the Ge doping layer 160 may deteriorate. When the thickness of the Ge doping layer 160 is less than 10 nm, the electron injection efficiency may be too low, When the thickness is within the range, the electron injection efficiency and the crystallinity of the Ge doping layer 160 can be excellent. This will be described in detail in the following experimental examples. However, the present invention is not limited thereto.

Alternatively, the Ge doping layer 160 may be composed of multiple layers, and may include a structure in which at least two or more different layers are repeatedly stacked, as shown in FIG. 2B. Referring to FIG. 2B, the Ge doping layer 160 may include a high-concentration Ge-doped layer 161 and a low-concentration doped layer 163. That is, the lightly doped layer 163 may be disposed under the relatively heavily doped Ge doping layer 161, and the lightly doped layer 163 may have a lower n-type dopant than the heavily doped Ge layer 161 It may have a dopant concentration. The highly doped Ge doping layer 161 may have substantially similar characteristics to the Ge doping layer 160 described in FIG. 2A, but its thickness is not limited.

Further, the high-concentration Ge doping layer 161 and the low-concentration doping layer 163 may be super lattice structures repeatedly laminated at least twice. At this time, the heavily doped Ge doping layer 161 has a thickness of about 5 x 10 18 atoms / cm 3 to about 8 x 10 20 atoms / cm 3 Concentration, and further, Ge at a concentration within a range of 1 x 10 19 atoms / cm 3 to 2 x 10 20 atoms / cm 3 . The lightly doped layer 163 may contain a relatively low concentration of Ge compared to the heavily doped Ge layer 161 and may also be an undoped layer not containing Ge. For example, the high-concentration Ge doping layer 161 may be a Ge-doped GaN layer, an AlGaN layer, an InGaN layer, or an AlInGaN layer, and the low-concentration Ge doping layer 161 may be an undoped GaN layer, an AlGaN layer, Layer, or an AlInGaN layer.

Further, in each of the high-concentration Ge doping layer 161 and / or the low-concentration doping layer 163, the n-type dopant may be modulation-doped. Further, the heavily doped Ge layer 161 and the lightly doped layer 163 may further include Si as an n-type dopant.

The total thickness of the Ge doping layer 160 including the superlattice structure may be 10 nm or more and 100 nm or less. When the thickness of the Ge doping layer 160 is larger than 100 nm, the crystallinity of the Ge doping layer 160 may be deteriorated. When the thickness of the Ge doping layer 160 is smaller than 10 nm, the electron injection efficiency may be too low. The thickness of each of the layers included in the superlattice structure may be from several nm to several tens nm, and the number of cycles of layers repeatedly laminated is not limited.

In addition to the structure of FIG. 2B, the light emitting device may further include a second Ge doping layer (not shown) located under the lightly doped layer 163. The second Ge doping layer may include an n-type dopant at a higher concentration than the lightly doped layer (163). In addition, the second Ge doping layer may include an n-type dopant at a lower concentration than the heavily doped Ge doping layer 161. Further, the high-concentration Ge doping layer 161, the low-concentration doping layer 163 and the second Ge doping layer may be formed in a superlattice structure in which the layers are stacked one or more times.

Referring again to FIG. 1, the active layer 170 may be located on the Ge doping layer 160. Furthermore, the active layer 170 may be located directly above the Ge doping layer 160 and may contact the Ge doping layer 160.

The active layer 170 may include a nitride-based semiconductor such as (Al, Ga, In) N and may be grown on the Ge doping layer 160. In addition, the active layer 170 may have a multiple quantum well structure (MQW) including a plurality of barrier layers and a well layer.

The multiple quantum well structure of the active layer 170 may include a barrier layer 171 having a relatively large band gap energy and a well layer 173 having a relatively small band gap energy. For example, the barrier layer 171 may be a GaN layer and the well layer 173 may be an InGaN layer. The element and the composition of the well layer 173 can be determined in consideration of the peak wavelength of the light to be emitted from the light emitting device 100 and the barrier layer 171 is formed in consideration of the band gap energy of the well layer 173 The element and composition of the nitride-based semiconductor constituting the barrier layer 171 can be determined so as to have a relatively larger band gap energy.

On the other hand, when the active layer 170 has a multiple quantum well structure, the barrier layer 171 may include a Ge-doped barrier layer.

Referring to FIG. 3A, the barrier layer 171 may be a Ge-doped barrier layer. The barrier layer 171 is Ge-doped to have an n-type conductivity, so that electrons can be supplied from the barrier layer 171 to the well layer 173. [ Therefore, the electron density in the well layer 173 increases, and the luminous efficiency of the luminous means 100 can be improved. According to the embodiment of the present invention, since the dopant included in the barrier layer 171 is Ge, even if the barrier layer 171 contains a dopant, the crystallinity of the barrier layer 171 due to the dopant does not deteriorate or deteriorate Can be minimized. Accordingly, since the barrier layer 171 includes a Ge-doped barrier layer, it is possible to improve the luminous efficiency while maintaining the crystallinity of the active layer 170. On the other hand, the barrier layer 171 has a Ge doping concentration of about 1 x 10 18 atoms / cm 3 to 5 x 10 18 atoms / cm 3 to 8 x 10 20 atoms / cm 3 More preferably 1 x 10 19 atoms / cm 3 to 2 x 10 20 atoms / cm 3 Concentration, but the present invention is not limited thereto.

Referring to FIG. 3B, the barrier layer 171 may include a Ge-doped barrier layer 171a and an undoped nitride-based semiconductor layer 171b. The undoped nitride based semiconductor layer 171b may be located above and below the Ge-doped barrier layer 171a. In one barrier layer, the thickness value of the Ge-doped barrier layer 171a may be less than or equal to the sum of the thicknesses of the two undoped nitride based semiconductor layers 171b. Thus, the maximum ratio of the thickness of the Ge-doped barrier layer 171a to the thickness of the two undoped nitride based semiconductor layers 171b may be 1: 1. The Ge doping concentration of the Ge-doped barrier layer 171a is about 1 x 10 18 atoms / cm 3 to 5 x 10 18 atoms / cm 3 to 8 x 10 20 atoms / cm 3 And more preferably in the range of 1 x 10 19 atoms / cm 3 to 2 x 10 20 atoms / cm 3 , but the present invention is not limited thereto.

The crystallinity of the barrier layer 171 can be further improved by locating the undoped nitride-based semiconductor layers 171b having relatively high crystallinity at the top and bottom of the Ge-doped barrier layer 171a. By controlling the thickness of the Ge-doped barrier layer 171a within the above-mentioned range, the undoped nitride-based semiconductor layers 171b are disposed on the upper and lower portions of the Ge-doped barrier layer 171a to improve the crystallinity The effect can be maximized.

The p-type nitride-based semiconductor layer 180 may include a nitride-based semiconductor such as (Al, Ga, In) N and may be grown on the active layer 170. The p-type nitride semiconductor layer 180 may include a p-type dopant, for example, Mg as a dopant. The p-type nitride semiconductor layer 180 may be formed using any known technique, and a detailed description thereof will be omitted herein.

The structure of the light emitting device 100 according to the present embodiment can be applied and applied to various types of light emitting devices.

4A and 4B are cross-sectional views illustrating a light emitting device according to another embodiment of the present invention.

The light emitting devices 100a and 100b of FIGS. 4A and 4B differ from the light emitting device 100 of FIG. 1 in that they further include a capacitor forming layer 140. Hereinafter, the light emitting devices 100a and 100b of FIGS. 4A and 4B will be mainly described, and detailed description of the same configuration will be omitted.

4A, the light emitting device 100a includes an n-type nitride based contact layer 130, a capacitor forming layer 140, a Ge doping layer 160, an active layer 170, and a p-type nitride based semiconductor layer 180 ). Further, the light emitting device 100a may further include a growth substrate 110 and a nitride-based lift-off layer 120.

The capacitor forming layer 140 may be interposed between the n-type nitride based contact layer 130 and the Ge doping layer 160 and may include a heavily doped layer 141 and a heavily doped layer 143. The lightly doped layer 143 is located on the heavily doped layer 141 and thus can be sandwiched between the Ge doped layer 1600 and the heavily doped layer 141.

The highly doped layer 141 may include a nitride-based semiconductor such as GaN, AlGaN, InGaN, or AlInGaN containing (Al, Ga, In) N, and may include GaN in particular. Further, when the high-concentration doping layer 141 contains AlGaN, InGaN, or AlInGaN, the molar fraction of Ga may be higher than the mole fraction of Al and / or In. The highly doped layer 141 can be grown by introducing a Group III atom source such as Al, Ga, In, etc., a Group V atom source such as N, and a Ge dopant atom source into the growth chamber. At this time, IBGe (Isobutylgermane) may be used as a Ge dopant atom source, but the present invention is not limited thereto.

The heavily doped layer 141 may contain a relatively high concentration of Ge as a dopant and may include, for example, at least about 1 x 10 18 atoms / cm 3, at least about 5 x 10 18 atoms / cm 3, and at most about 8 x 10 20 atoms / cm 3 More preferably 1 x 10 19 atoms / cm 3 to 2 x 10 20 atoms / cm 3 The Ge atoms in the concentration range can be contained as a dopant. Since the high concentration doping layer 141 contains Ge as a dopant, excellent crystallinity can be maintained even if doped at a relatively high concentration. At this time, the thickness of the highly doped layer 141 may be 100 nm or less, and further, it may be within the range of 10 to 100 nm. The highly doped layer 141 has a thickness within a range of 10 to 100 nm, and thus can have excellent crystallinity.

The lightly doped layer 143 may include a nitride-based semiconductor such as GaN, AlGaN, InGaN, or AlInGaN containing (Al, Ga, In) N, and may include GaN in particular. The lightly doped layer 143 may contain a relatively low concentration of Ge dopant relative to the heavily doped layer 141 and may also be undoped.

The capacitor forming layer 140 includes the high concentration doping layer 141 and the low concentration doping layer 143 located on the high concentration doping layer 141 so that the high concentration doping layer 141 / (160) may be sequentially stacked. Accordingly, a lightly doped (or undoped) layer is displayed between the heavily doped layers, so that a capacitor can be formed inside the light emitting device 100a. When a reverse voltage is applied to the light emitting device 100a due to a cause of electrostatic discharge or the like, such a capacitor can save charges and prevent the light emitting device 100a from being damaged by reverse bias according to a reverse voltage. Accordingly, by including the capacitor forming layer 140, the light emitting device 100a improves the internal capacitance and improves the resistance to electrostatic discharge, thereby improving the electrical reliability of the light emitting device 100a.

Also, by doping the heavily doped layer 141 included in the capacitor forming layer 140 with Ge, the crystallinity of the other layers grown on the capacitor forming layer 140 can be prevented from deteriorating.

4B, the light emitting device 100b includes an n-type nitride based contact layer 130, a capacitor forming layer 140, a superlattice layer 150, a Ge doping layer 160, an active layer 170, and a p Type semiconductor layer 180. The nitride- Further, the light emitting device 100b may further include a growth substrate 110 and a nitride-based on-pattern layer 120.

The light emitting device 100b of FIG. 4b differs from the light emitting device 100a of FIG. 4a in that it further includes a superlattice layer 150 and the structure of the capacitor forming layer 140 is different. Hereinafter, differences will be mainly described, and detailed description of the same configuration will be omitted.

The superlattice layer 150 may be positioned between the Ge doping layer 160 and the capacitor forming layer 140 and the capacitor forming layer 140 may be located between the n type nitride based contact layer 130 and the superlattice layer 150 As shown in FIG. The superlattice layer 150 is substantially similar to that described with reference to FIG. 1, and a detailed description thereof will be omitted.

The capacitor forming layer 140 includes a first heavily doped layer 141, a second heavily doped layer 145 and a heavily doped layer 145 disposed between the first heavily doped layer 141 and the second heavily doped layer 145, (143). Accordingly, a lightly doped layer interposed between the heavily doped layers is provided, so that a capacitor can be formed inside the light emitting device 100b. Accordingly, the capacitance of the light emitting device 100b can be improved, and the resistance to electrostatic discharge can be improved to improve the electrical reliability of the light emitting device 100b.

Meanwhile, the first high-concentration doping layer 141 and the second high-concentration doping layer 145 are substantially similar to the high-concentration doping layer 141 described with reference to FIG. 4A, and a detailed description thereof will be omitted. However, the material and doping concentration of the first high-concentration doping layer 141 and the second high-concentration doping layer 145 may be the same or different from each other.

5 is a cross-sectional view illustrating a light emitting device according to another embodiment of the present invention.

The light emitting device 100c of FIG. 5 may be formed from the light emitting device 100 having the structure of FIG. 1, and a detailed description of the same configuration will be omitted.

5, the light emitting device 100c includes an n-type nitride-based contact layer 130, a Ge doping layer 160, an active layer 170, and a p-type nitride-based semiconductor layer 180. Further, the light emitting device 100c may further include a growth substrate 110, a nitride-based undoped layer 120, a superlattice layer 150, a first electrode 191, and a second electrode 193 .

The light emitting device 100c may include a mesa including a p-type nitride semiconductor layer 180, an active layer 170, a Ge doping layer 160, and a superlattice layer 150, The n-type nitride based contact layer 130 may be partially exposed. The mesa may be formed by partially removing the p-type nitride semiconductor layer 180, the active layer 170, the Ge doping layer 160, and the superlattice layer 150 through photolithography and etching processes.

The first electrode 191 is located on a region where the n-type nitride based contact layer 130 is partially exposed and can be electrically connected to the n-type nitride based contact layer 130. The second electrode 193, Type semiconductor layer 180 and may be electrically connected to each other. The first and second electrodes 191 and 193 may be electrically connected to an external power source to supply power to the light emitting device 100c.

Accordingly, a horizontal type light emitting device can be provided, and the light emitting device 100c of the present embodiment can also be applied and applied to a flip chip type light emitting device. Further, the growth substrate 110 and / or the nitride-based on-pattern layer 120 may be separated and removed.

6 is a cross-sectional view illustrating a light emitting device according to another embodiment of the present invention.

6, the light emitting device 100d includes an n-type nitride-based contact layer 130, a Ge doping layer 160, an active layer 170, and a p-type nitride-based semiconductor layer 180. Further, the light emitting device 100d may further include a superlattice layer 150, a first electrode 191, and a second electrode 193.

The light emitting device 100d removes the growth substrate 110 in the structure of the light emitting device 100 of FIG. 1 and the nitride based on-pattern layer 120 may be additionally removed after the growth substrate 110 is removed . Type nitride semiconductor layer 130 is formed on the lower surface of the exposed n-type nitride-based contact layer 130 by removing the growth substrate 110 and the nitride-based on-pattern layer 120, and the p- The vertical light emitting device shown in FIG. 6 can be provided by forming the second electrode 193 on the first electrode 180.

However, the structures of the light emitting device described in Figs. 5 and 6 are merely illustrative, and the present invention is not limited thereto.

Hereinafter, the variation of the surface roughness RMS according to the doping concentration of the Ge doping layer and the thickness of the Ge doping layer will be described.

(Experimental Example 1)

According to the above-described embodiments, a Ge doping layer having a thickness of 10 nm was formed. Table 1 shows the results of measuring the surface roughness RMS of the Ge doped layer formed according to the IBGe flow rate. The Ge doping concentration of the Ge doping layer is changed depending on the flow rate of IBGe, and the Ge concentration of the sample 2 and the sample 3 is 5 × 10 18 atoms / cm 3 to 2 × 10 20 atoms / cm 3 Lt; / RTI >

Figure pat00001

From the results of Table 1, it can be seen that the surface roughness RMS value of the Ge doping layer is not correlated with the Ge doping concentration. Therefore, it is understood that the crystallinity of the Ge doping layer does not change greatly depending on the Ge doping concentration.

(Experimental Example 2)

According to the above-described embodiments, a Ge doping layer having a thickness of 10, 40, 100, and 300 nm, respectively, was formed. These Ge-doped layers are shown as Samples A to D, and the surface roughness RMS values for each sample are shown in Table 2 below.

Figure pat00002

As a result of Table 2, the surface roughness RMS value of the Ge doping layer was found to increase when the thickness of the Ge doping layer was out of a certain range. From the results shown in Table 2, it can be seen that the Ge doping layer has a good crystallinity when the thickness is in the range of 10 nm to 100 nm, and the crystallinity deteriorates when the thickness of the Ge doping layer exceeds 100 nm.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (16)

An n-type nitride based contact layer comprising a Si dopant;
A Ge doping layer positioned on the n-type nitride based contact layer and including a Ge dopant;
An active layer located on the Ge doping layer; And
And a p-type nitride-based semiconductor layer located on the active layer,
Wherein the Ge doping layer has a thickness in the range of 10 to 100 nm,
And the electron concentration of the Ge doping layer is higher than the electron concentration of the n-type nitride-based contact layer. The method according to claim 1,
Wherein the Ge doping layer further comprises an Si dopant. The method according to claim 1,
The Ge doping layer may have a thickness of 5 x 10 18 atoms / cm 3 to 8 x 10 20 atoms / cm 3 Lt; RTI ID = 0.0 > Ge < / RTI > The method of claim 3,
The Ge doping layer may have a concentration of 1 x 10 19 atoms / cm 3 to 2 x 10 20 atoms / cm 3 Lt; RTI ID = 0.0 > Ge < / RTI > The method according to claim 1,
Further comprising a low concentration doping layer located under the Ge doping layer,
Wherein the lightly doped layer includes an n-type dopant having a concentration lower than that of the Ge-doped layer. The method of claim 5,
Wherein the Ge doping layer and the lightly doped layer are repeatedly laminated at least twice to form a superlattice structure. The method of claim 6,
Wherein the lightly doped layer is a modulation-doped light-emitting device. The method of claim 6,
Wherein the Ge doping layer is modulation-doped with Ge. The method of claim 6,
A second Ge doping layer located at the lower end of the lightly doped layer and including a Ge dopant,
And the second Ge doping layer includes an n-type dopant having a higher concentration than the lightly doped layer. The method of claim 9,
Wherein the lightly doped layer is a modulation-doped light-emitting device. The method of claim 9,
Wherein the Ge doping layer is modulation-doped with Ge. The method according to claim 1,
And a superlattice layer disposed between the n-type nitride-based contact layer and the Ge-doped layer, wherein the superlattice layer is formed by stacking two or more layers having different composition ratios and one or more periods. The method of claim 2,
And the Ge dopant concentration in the Ge doping layer is higher than the Si dopant concentration in the Ge doping layer. The method according to claim 1,
Wherein the Ge doping layer comprises at least one of GaN, AlGaN, InGaN, and AlInGaN,
The mole fraction of Ga in each of AlGaN, InGaN and AlInGaN is higher than the mole fraction of Al and / or In. The method according to claim 1,
Wherein the active layer includes a multiple quantum well structure in which a barrier layer and a well layer are repeatedly stacked,
Wherein the barrier layer comprises a Ge doped layer. 16. The method of claim 15,
Wherein the barrier layer comprises lightly doped layers located above and below the Ge doped layer,
Wherein the lightly doped layer comprises a Ge dopant at a lower concentration than the Ge-doped layer of the barrier layer, or an undoped light emitting element.
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Cited By (1)

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Publication number Priority date Publication date Assignee Title
CN117810332A (en) * 2024-03-01 2024-04-02 江西兆驰半导体有限公司 Gallium nitride-based light-emitting diode epitaxial wafer and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117810332A (en) * 2024-03-01 2024-04-02 江西兆驰半导体有限公司 Gallium nitride-based light-emitting diode epitaxial wafer and preparation method thereof
CN117810332B (en) * 2024-03-01 2024-05-17 江西兆驰半导体有限公司 Gallium nitride-based light-emitting diode epitaxial wafer and preparation method thereof

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