KR101613556B1 - method for fabricating nitride semiconductor device - Google Patents

Abstract

A method for manufacturing a nonpolar m-plane nitride semiconductor device, comprising the steps of: preparing a substrate; forming a first semiconductor layer on a substrate in an atmosphere containing N2 gas; Forming an active layer on the semiconductor layer, forming a second semiconductor layer on the active layer in an atmosphere containing H2 gas, and forming electrodes on the first and second semiconductor layers, respectively.

Description

TECHNICAL FIELD The present invention relates to a method for fabricating a nitride semiconductor device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a method of manufacturing a non-polar m-plane nitride semiconductor device.

Recently, the development of light emitting diodes and blue-violet laser diodes covering the red wavelength band in ultraviolet rays has been completed in accordance with the growth technology of c-plane nitride semiconductor and has already been widely used in optical data storage, optical sensors, .

In addition, the development of green laser diodes is underway, and it is expected to play a pivotal role as a progressive next-generation technology in commercialization of applications such as Pico project by enhancing the perfection of color implementation through RGB laser.

On the other hand, the growth of conventional polarized nitride semiconductors for realizing the green wavelength light presents various problems.

Spontaneous polarization and piezoelectric polarization along the polar growth direction create a large built-in electric field in the quantum well.

This leads to a reduction in radiative efficiency, such as QCSE (Quantum Confined Stark Effect), and a blue-shift problem at the oscillation wavelength.

On the other hand, in the case of an m-plane nitride semiconductor, there is no QCSE and a large wave function and a high radiative recombination ratio due to the combination of electrons and holes can be obtained, and a blue- shift), it is widely regarded as a substitute nitride semiconductor in the cyan and green wavelength spectral bands because it is relatively smaller than the polar nitride semiconductor.

However, in the case of nonpolar nitride semiconductors, it is difficult to inject In in the quantum well at a wavelength of 520 nm in green wavelength region, compared with the case of the polar nitride semiconductor, and the problem of development and improvement due to a decrease in slope efficiency due to low internal quantum efficiency There is a lot left.

Nonetheless, until now, nonpolar and semipolar nitride semiconductors have been attracting attention and research as promising materials for the realization of high output blue, cyan, and green laser diodes.

An object of the present invention is to provide a nitride semiconductor light emitting device and a nitride semiconductor light emitting device which can maintain the atmosphere containing N 2 gas until the n-type semiconductor layer and the active layer are grown during the growth of the apolar nitride semiconductor, And to provide a method for manufacturing a nitride semiconductor device having a uniform surface and minimizing a step and size of a pyramidal shape resulting from inherent crystallinity and having good electrical characteristics.

Another object of the present invention is to provide a nitride semiconductor device manufacturing method capable of forming ohmic contact with an electrode by implanting p-type impurity having a concentration of 1e19 / cm3 or more into the p-type contact layer during growth of apolar nitride semiconductor .

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise forms disclosed. .

A method for fabricating a nitride semiconductor device according to the present invention includes the steps of preparing a substrate, forming a first semiconductor layer on a substrate in an atmosphere containing N2 gas, Forming an active layer on the first semiconductor layer, forming a second semiconductor layer on the active layer in an atmosphere containing H2 gas, and forming electrodes on the first and second semiconductor layers, respectively.

Here, the first and second semiconductor layers and the active layer may be a non-polar (10-10) plane of the gallium nitride substrate or a plane grown from an inclined plane having a range of 0 to 5 degrees from the non-polar (10-10) have.

The step of forming the first semiconductor layer can sequentially grow the first contact layer, the first clad layer, and the first optical guide layer on the substrate in an atmosphere containing N2 gas, and form an active layer The step of forming an active layer and a cap layer sequentially on the first semiconductor layer in an atmosphere containing N2 gas and the step of forming a second semiconductor layer include the steps of forming a second semiconductor layer on the active layer, Layer, the second clad layer, and the second contact layer can be sequentially grown.

Next, in the second contact layer growth, the minimum concentration of the impurities to be implanted may be 1e19 / cm3 or more. At the time of the second contact layer growth, the concentration of the impurities to be implanted gradually increases in the thickness direction from the lower surface to the upper surface, It may gradually decrease, or may be totally the same.

Other objects, features and advantages of the present invention will become apparent from the detailed description of embodiments with reference to the accompanying drawings.

The method for fabricating a nitride semiconductor device according to the present invention has the following effects.

In the nitride semiconductor growth, the atmosphere containing N 2 gas is maintained until the growth of the n-type semiconductor layer and the active layer to minimize the surface roughness of each layer, and the atmosphere containing H 2 gas is maintained Thereby maximizing the electrical characteristics.

The present invention also provides a method of forming a p-type semiconductor layer by implanting a p-type impurity having a concentration of 1e19 / cm3 or more into the p-type contact layer during the growth of the p-type semiconductor layer to improve the formation of ohmic contacts with the p- A nitride semiconductor device having optical device characteristics can be manufactured.

1 is a structural cross-sectional view showing a nitride semiconductor device according to the present invention;
2A is a view showing a growth process of a nitride semiconductor layer
2B is a graph showing the growth temperature of the nitride semiconductor layer
Figure 3 is a graph showing the CP2Mg flow and concentration of the m-plane gallium nitride contact layer
4 is a graph showing the Mg doping levels according to the CP2Mg flow of the c-plane and m-plane gallium nitride contact layers

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

The present invention relates to a method of manufacturing an m-plane nitride semiconductor device, and more particularly, to a method of manufacturing an n-type nitride semiconductor device, AlGaN and a GaN or InGaN material are grown and grown in an atmosphere containing H2 gas when the p-type semiconductor layer, which is a light guide layer and a light confinement layer, is grown secondarily after the active layer, thereby maintaining a maximum uniform surface, It is possible to realize a photosemiconductor laser device having an electrical characteristic of the optical semiconductor laser device.

That is, the present invention relates to a method of growing a current injection layer that primarily exhibits n-type characteristics, starting from an atmosphere containing N2 gas for minimizing substrate defects at an elevated temperature before the growth of the n-type GaN buffer, GAN or AlGaN and GaN or InGaN materials are grown in an atmosphere containing N2 gas, and when the p-type semiconductor layer, which is a light guide layer and a light confinement layer, is grown secondarily after the active layer is grown in an atmosphere containing H2 gas, A photosemiconductor laser device having a uniform surface and having good electrical characteristics can be realized.

Here, the n-type semiconductor layer is grown in an atmosphere containing N2 gas to minimize surface roughness, and the p-type semiconductor layer can grow in an atmosphere containing H2 gas to maximize electrical characteristics.

In the nonpolar nitride semiconductor, when the atmosphere containing N 2 gas is used, the step and size of the surface pyramid shape, which is inherent in the growth from the crystal plane due to the mechanical and chemical treatment surface treatment of the substrate itself, It is possible to form a uniform and flat n-type thin film structure by minimizing the bonding interference due to H2 in the Ga-N bond structure.

In addition, when the GaN or InGaN material is grown while the temperature is lowered in the atmosphere containing the same N 2 gas after the growth of the n-type current injection layer at a high temperature, the deposition atmosphere of the interface is made uniform, It is possible to reduce the unstable etching in the atmosphere containing H2 gas, thereby reducing aggregation of In atoms and making the In composition uniform.

On the other hand, at the time of growing the p-type semiconductor layer, which is the light guide layer and the light confinement layer, after growing the active layer, the growth atmosphere is converted into the atmosphere containing H2 gas and grown to grow the hole by the p-type impurity implantation, It is possible to improve the contact formation, minimize the defects of the device, and manufacture a photo-laser semiconductor device having good optical device characteristics.

When growing a nitride semiconductor optical device using a GaN substrate having a non-polar (10-10) plane as a base material, a p-type impurity is implanted into a p-type GaN layer which is the uppermost contact layer in contact with the GaN or AlGaN layer as the p- , The minimum p-type impurity concentration should be at least about 1e19 / cm3 in order to form an ohmic contact.

The reason for this is that when the p-type impurity is injected into the p-type contact GaN layer which is in contact with the p-type pad (p-pad) as compared with the c-plane nitride semiconductor, the m- Is relatively low.

Therefore, in order to maintain ohmic formation at a level similar to that of an ohmic metal of a conventional polar nitride semiconductor, a p-type impurity concentration must be further injected in the non-polar nitride semiconductor, The holes can be coupled with electrons in the active layer through the p-layer.

As a method of implanting p-type impurity into the p-type contact GaN layer, there is a method of injecting only a predetermined amount from the initial growth stage to the final growth stage, or a method of injecting a small amount at the initial growth stage, There is a method of injecting impurities, and conversely, there is a method of growing a small amount while injecting a large amount at the initial growth.

In the present invention, when a nonpolar nitride semiconductor optical device using a GaN substrate as a base material for a nonpolar (10-10) plane is manufactured, whichever injection method is adopted for an arbitrary thickness of the p-type contact layer, , and the concentration of the p-type impurity is about 1e19 / cm3 or more.

Conditions for growing the p-type contact GaN layer include a growth temperature, a V / III ratio, a growth pressure, a growth rate, a carrier gas atmosphere, and the like. It is necessary to implant a p-type impurity in order to form an ohmic metal and an ohmic of the p-type impurity. At that time, the concentration of the p-type impurity is required to be at least 1e19 / cm3.

FIG. 1 is a structural cross-sectional view showing a nitride semiconductor device according to the present invention. FIG. 1 shows a structure in which a device is cut at a position perpendicular to a resonant direction of laser light after epitaxial growth of a laser device.

As shown in Fig. 1, first, a non-polar m-plane GaN substrate is prepared.

Here, the gallium nitride substrate grows a semiconductor layer from a non-polar (10-10) plane or a non-polar (10-10) plane from a slope having a range of 0 degrees to 5 degrees.

Then, in the atmosphere 14 containing N2 gas, the first semiconductor layer is formed on the substrate.

 Here, the first semiconductor layer is an n-type semiconductor layer. The n-type contact layer 3, the n-type cladding layer 4, and the n-type optical guide layer 5 are formed on a gallium nitride substrate in an atmosphere containing N2 gas, Are successively grown.

Then, the active layer 6 is formed on the first semiconductor layer by continuously maintaining the atmosphere 14 containing the N2 gas.

Here, the cap layer 7 may be further formed on the active layer 6 in the atmosphere 14 containing N2 gas, which may be omitted in some cases.

Next, a second semiconductor layer is formed on the active layer 6 in an atmosphere 13 containing H2 gas. The second semiconductor layer is a p-type semiconductor layer which is formed on the active layer 6 in an atmosphere containing H2 gas the p-type optical guide layer 8, the p-type cladding layer 9, and the p-type contact layer 10 are successively grown.

Here, when growing the p-type contact layer 10, the minimum concentration of the p-type impurity implanted should be not less than about 1e19 / cm3.

The reason for this is that when the p-type impurity is injected into the p-type contact GaN layer which is in contact with the p-type pad (p-pad) as compared with the c-plane nitride semiconductor, the m- Is relatively low.

Therefore, in order to maintain ohmic formation at a level similar to that of an ohmic metal of a conventional polar nitride semiconductor, a p-type impurity concentration must be further injected in the non-polar nitride semiconductor, The holes can be coupled with electrons in the active layer through the p-layer.

Then, when the p-type contact layer is grown, the p-type impurity to be implanted can be implanted by the following three methods.

The first method is a method in which the concentration of the p-type impurity to be implanted is gradually increased in the thickness direction from the lower surface to the upper surface. In the second method, the concentration of the impurity to be implanted is increased in the thickness direction And the third method is a method in which the concentration of the impurity to be implanted is the same in the thickness direction from the lower surface to the upper surface.

In the next step, the n-type electrode and the p-type electrode are formed on the first and second semiconductor layers that have undergone the epitaxial growth, thereby completing the fabrication of the device.

2A and 2B are diagrams for explaining a method of manufacturing a nitride semiconductor device according to the present invention, wherein FIG. 2A is a graph showing a growth process of a nitride semiconductor layer, and FIG. 2B is a graph showing a growth temperature of a nitride semiconductor layer .

As a crystal growth method of a nitride compound semiconductor, an MOCVD method, a molecular beam epitaxy (MBE) method, and a HILPE vapor phase epitaxy (HVPE) method may be used. In consideration of crystallinity and productivity, It is desirable to use the method.

In order to epitaxially grow the nitride semiconductor layer, first, a GaN substrate having a slope of 0 degrees or more and 5 degrees or less from a nonpolar (10-10) plane or a nonpolar (10-10) plane is prepared as a base substrate.

In this manner, the prepared base substrate is cleaned and the base substrate is placed in the crystal growth apparatus.

Herein, the crystal growth apparatus is an MOCVD apparatus in which a GaN substrate substrate is provided on a susceptor made of a silicon carbide (SiC) material. A heater for resistance heating is disposed in the susceptor, Can be controlled.

In the crystal growth apparatus, ammonia is used as the Group 5 element, trimethyl gallium, trimethyl aluminum, trimethyl indium are used as the Group III element, nitrogen gas or hydrogen gas Lt; / RTI >

Next, SiH4 is used as a donor doping material and magnesium (Cp2Mg) is used as an acceptor doping material of a P type.

Each raw material is regulated to be introduced into the reaction tube from the raw material source by controlling the flow rate accurately using a mass flow controller (MFC), and is configured to be discharged from the exhaust gas outlet.

When the base substrate is mounted on the crystal growth apparatus thus constituted, the temperature is raised to about 900 to 1100 degrees while maintaining the atmosphere containing nitrogen gas, and TMG and SiH4 gas are supplied to grow the n-type contact layer (100)

The n-type contact layer is preferably made of GaN doped with an n-type impurity. The concentration of the n-type impurity can be adjusted to about 1e17 / cm3-1e21 / .

If the n-type impurity concentration is less than about 1e17 / cm3, a desirable resistance ohmic is difficult to obtain, and a decrease in threshold current and voltage in the laser device can not be seen.

If the n-type impurity concentration is larger than about 1e21 / cm3, the leak current of the device itself may increase, or the crystallinity may be deteriorated, so that the lifetime of the device may be shortened.

If the thickness of the n-type contact layer is less than about 0.2 um, it is difficult to control the etching rate when the electrode is formed. If the thickness is more than 4 um The crystallinity may be deteriorated.

Next, while maintaining the atmosphere containing nitrogen gas, TMAl is supplied to grow the n-type cladding layer. (100)

The n-type cladding layer serves as a carrier confinement layer and a layer for blocking light, and is formed of a nitride semiconductor containing Al doped with an n-type impurity, preferably a super lattice structure of a nitride semiconductor layer containing Al Or a single film of AlGaN may also be included.

The n-type impurity concentration of the n-type cladding layer is adjusted in the range of about 5e16 / cm3 to about 1e21 / cm3, preferably about 1e17 / cm3 to about 1e19 / cm3.

The thickness of the n-type cladding layer is preferably adjusted to about 100 Å or more and about 2 μm or less. The nitride semiconductor layers constituting the super lattice structure of the n-type cladding layer may be composed of nitride semiconductors having different compositions from each other, It is most preferable to repeat GaN or AlGaN having different band gap energies.

The Al composition of the n-type cladding layer is preferably greater than 0 and less than 30, and the thickness of each of the nitride semiconductor layers constituting the super lattice layer can be adjusted to a range of about 100 Å or less to 10 Å or more. The thickness becomes thicker than the elastic distortion limit, and a lattice defect such as a minute crack is present in the film.

The nitride semiconductor layers A and B constituting the superlattice layer are preferably laminated with layers having different band gap energies and the average band gap energy of the nitride semiconductor constituting the superlattice layer is made larger than that of the active layer .

Here, in the case of doping the nitride semiconductor constituting the super lattice layer, the n-type impurity may be doped in both the A layer and the B layer, and it may be doped only in either layer, or the A layer and the B layer The amount of doping may be the same or the amount of impurities may be different from each other.

At this time, the n-type impurity is preferably a Group 4 element such as Si.

Next, while the atmosphere containing nitrogen gas is maintained, the supply of TMAl is stopped to grow the n-type optical guide layer. (100)

The n-type optical guide layer is composed of a nitride semiconductor layer serving as a light guide for the active layer, having a larger band gap energy than the active layer, and a lower band gap energy than the n-type cladding layer.

The thickness is about 100 Å or more and 5 μm or less, and the n-type impurity may be doped or not doped, and the layer not doped may have fewer crystal defects, and a better quality active layer can be grown.

However, in the case where the n-type impurity is not doped, since the light absorption is small, most of the light emission of the active layer is not absorbed and is trapped in the cladding layer, so that the n-type optical guide layer is preferably not doped.

Next, the InGaN layer is grown by supplying TMIn in an inert gas atmosphere such as N 2 at a temperature of about 700 to 900 ° C. (100)

This temperature is a parameter that determines the emission wavelength of the light emitting device, and the wavelength tends to become longer as the temperature goes down.

The growth rate is preferably 2 A / min or more and 100 A / min or less, preferably as low as possible, and a thickness of about 5 Å to 0.1 袖 m. (200)

In this case, In may be grown from 0% to 20% or less, but the composition may be gradually increased or decreased. This layer may be grown by growing a layer of InGaN or GaN at a low speed instead of the growth- And is present as a layer for obtaining a better quality active layer.

Then, if the temperature is stabilized, the active layer is grown by supplying TMGa and TMIn while maintaining an atmosphere containing nitrogen gas. (300)

Here, the active layer is composed of a nitride semiconductor layer containing In, and preferably, the well layer is made of InGaN and the barrier layer is made of InGaN or GaN.

In the case of the well layer, it is preferable to increase the amount of In more than the barrier layer. The preferable thickness of the well layer is about 100 angstroms or less, and the preferable thickness of the barrier layer is about 150 angstroms or less.

Further, it is preferable to use an MQW structure, and SQW may be used.

When the active layer is doped with impurities, both the well layer and the barrier layer may be doped, and either one of them may be doped. Normally, if the number of layers of the well layer is five to five, It is more likely to be a good device.

When the active layer is grown, the well layer and the barrier layer are grown in the middle or in the case of MQW.

This can prevent the desorption of In atoms that occur during the growth downtime, reduce unstable etching at high temperatures, reduce the aggregation of In atoms, and improve the quality of the active layer by making the In composition uniform.

Next, TMGa, TMGa, TMIn, TMGa, TMIn, and TMAl are supplied to grow a GaN or InGaN or AlInGaN layer in the process of raising the temperature of the P-type layer after the active layer is grown.

This maximum temperature is a temperature for growing the P-type semiconductor layer, and the hydrogen atmosphere is gradually maintained between about 900 and about 1100 degrees.

The growth rate is preferably about 2 Å / min to 100 Å / min or less, preferably as low as possible, and a thickness of about 5 Å to 0.1 袖 m. (400)

It is also possible to increase or decrease the composition gradually from 0% to 20% of In and from 0% to 20% of Al, and to lower the lattice constant of the cap layer from the maximally higher side in terms of the lattice constant .

This layer improves the interfacial characteristics after growth of the active layer by growing the InGaN or GaN or AlInGaN layer at low speed instead of the growth stop step of the conventional growth method of the active layer and reduces the propagated potential to improve the quality of the P- As a layer for obtaining a semiconductor layer.

Then, after growth of the active layer, TMGa and TMAl are supplied for the purpose of preventing sublimation of the InGaN film and for the purpose of carrier blocking, and a p-side cap layer made of an AlGaN layer is grown.

The p-type cap layer grows a nitride semiconductor layer having a larger band gap energy and a larger band gap energy than the p-type optical guide layer to a film thickness of about 0.1 탆 or less.

The AlGaN layer preferably has a Al composition of 10% or more. If the AlGaN layer is grown to a thickness greater than about 0.1 um, cracks tend to be formed in the film, making it difficult to grow a film with good crystallinity.

Although the lower limit of the film thickness at which the carrier does not allow the energy barrier to pass through the tunnel effect is not particularly specified, it is preferable to grow the film at a film thickness of about 10 angstroms or more.

The P-type cap layer may be doped with impurities or not doped. If doping is performed, Cp2Mg is supplied to dope the p-type impurity.

This layer may be omitted.

Thereafter, a p-type optical guide layer is grown. (500)

The p-type optical guide layer is composed of a nitride semiconductor layer serving as a light guide of the active layer, having a band gap energy larger than that of the active layer, and having a lower band gap energy than the p-type cladding layer.

The thickness is about 100 Å or more and 5 μm or less, and the p-type impurity may be doped or not doped. The doped layer has less crystal defects, and a better quality p-side cladding layer can be grown.

the p-type optical guide layer is more preferably not doped, because the light absorption of the p-type optical waveguide layer is less than that of the p-type optical waveguide layer, And a p-type impurity diffused from the layer.

If doping, Cp2Mg is supplied to dope the p-type impurity.

Next, TMGa, TMAl, and Cp2Mg are supplied to grow a p-type cladding layer. (500)

The p-type cladding layer functions as a carrier confinement layer and a layer for blocking light, and is formed of a nitride semiconductor containing Al doped with a p-type impurity.

A superlattice structure of a nitride semiconductor layer containing Al or a single film of AlGaN is also preferable.

The p-type impurity concentration is adjusted in the range of about 1e17 / cm3 to about 5e21 / cm3, preferably about 1e18 / cm3 to about 5e20 / cm3.

The thickness of the P-type cladding layer is preferably adjusted to about 100 Å or more and 2 μm or less. The nitride semiconductor layers constituting the superlattice structure of the p-type cladding layer may be composed of nitride semiconductors having different compositions from each other. It is most preferable to repeat different GaN and AlGaN.

The Al composition is preferably more than 0 and less than 30, and the film thickness of each nitride semiconductor layer constituting the superlattice layer is adjusted to a range of about 100 angstroms or less to about 10 angstroms or more. And a lattice defect such as a minute crack is present in the film.

The nitride semiconductor layers A and B constituting the superlattice layer are preferably laminated with layers having different band gap energies and the average band gap energy of the nitride semiconductor constituting the superlattice layer is made larger than that of the active layer .

In the case of doping the nitride semiconductor constituting the superlattice layer, the p-type impurity may be doped in both the A-layer and the B-layer, and it may be doped to only one of the A-layer and the B- The amount of doping may be the same or the amount of impurities may be different from each other.

Here, the p-type impurity is a Group 2 element of Mg and Cp2Mg is used.

Next, the supply of TMAl is stopped, and a p-type contact layer is grown (500)

The P-type contact layer is preferably made of Mg-doped GaN, and Cp2Mg is used.

Here, as a method of implanting p-type impurity into the p-type contact layer, there is a method of injecting only a predetermined amount from the initial growth stage to the final growth stage, or there is a method in which a small amount of impurity is injected at the initial growth stage, In contrast, there is a method in which a large amount is injected at the time of initial growth and then the growth is reduced to a small amount.

In the present invention, the concentration of the p-type impurity is set to be not less than about 1e19 / cm < 3 > at the time of implanting the p-type impurity regardless of the above-described implantation method with respect to an optional thickness of the p-

The reason for this is that when the p-type impurity is injected into the p-type contact GaN layer which is in contact with the p-type pad (p-pad) as compared with the c-plane nitride semiconductor, the m- Is relatively low.

Therefore, in order to maintain ohmic formation at a level similar to that of an ohmic metal of a conventional polar nitride semiconductor, a p-type impurity concentration must be further injected in the non-polar nitride semiconductor, The holes can be coupled with electrons in the active layer through the p-layer.

The thickness of the P-type contact layer is preferably about 100 Å or more and 1 μm or less, but it is preferable to make the thickness of the p-type contact layer as thin as possible.

Because the p-type cladding layer is in contact with the p-type cladding layer made of p-type AlGaN, if the thickness is reduced, the carrier of the p-type cladding layer is more likely to move to the p-type contact layer. A resistance ohmic is obtained.

Subsequently, after the p-type contact layer growth is terminated, the substrate heating is stopped and the epitaxial growth of the light emitting element is terminated.

As described above, according to the present invention, GaN or AlGaN, GaN, or InGaN materials are grown in an atmosphere containing N 2 gas for growth of a current injection layer primarily showing n-type characteristics and growth of an active layer, In the subsequent growth of the p-type semiconductor layer, which is the optical guide layer and the light confinement layer, in the atmosphere containing H2 gas, the optical semiconductor laser device having the maximum uniform surface and having the ohmic electrical characteristics can be realized have.

When the p-type impurity is implanted into the p-type GaN layer which is the uppermost contact layer in contact with the GaN or AlGaN layer which is the p-type light confinement layer, the concentration of the minimum p-type impurity is about 1e19 / So as to form an ohmic contact.

FIG. 3 is a graph showing the formation of ohmic by the CP2Mg flow and concentration of the m-plane gallium nitride contact layer. As shown in FIG. 3, when forming the gallium nitride contact layer, the concentration of Mg as the p- / cm < 3 > or more, a preferable ohmic contact is formed.

That is, in the non-polar m-plane nitride contact layer of the present invention, the concentration of the p-type impurity is lower than that of the conventional polarized c-plane nitride contact layer, so that an ohmic contact similar to the polar c- In order to form the desired ohmic contact, the concentration of the p-type impurity should be at least about 1e19 / cm3.

4 is a graph showing the Mg doping level according to the CP2Mg flow of the c-plane and m-plane gallium nitride contact layers. As shown in Fig. 4, a p-type impurity is added to the p- It can be seen that, when injected, the nonpolar m-plane nitride semiconductor is injected with a lower concentration of the p-type impurity relative to the polar c-plane nitride semiconductor.

Therefore, in order to form an ohmic contact of a level similar to that of the conventional polar nitride semiconductor, in the case of the non-polar nitride semiconductor according to the present invention, the p-type impurity concentration must be higher than that of the polar nitride semiconductor, The holes can be coupled with electrons in the active layer through the p-layer.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments but should be determined according to the claims.

Claims (9)

Preparing a substrate;
Forming a first semiconductor layer on the substrate in an atmosphere containing N ₂ gas;
Forming an active layer on the first semiconductor layer while maintaining an atmosphere containing the N ₂ gas;
Forming a second semiconductor layer on the active layer in an atmosphere containing H ₂ gas; And,
And forming electrodes on the first and second semiconductor layers, respectively,
Wherein the first and second semiconductor layers and the active layer are layers grown from a nonpolar (10-10) plane of the gallium nitride substrate or an inclined plane having a range of 0 to 5 degrees from the nonpolar (10-10) plane Wherein the nitride semiconductor layer is formed on the nitride semiconductor layer. delete The method of claim 1, wherein forming the first semiconductor layer comprises:
Wherein the first contact layer, the first clad layer, and the first optical guide layer are sequentially grown on the substrate in an atmosphere containing the N ₂ gas. The method of claim 1, wherein forming the active layer comprises:
Wherein the active layer and the cap layer are sequentially grown on the first semiconductor layer in an atmosphere containing the N ₂ gas. The method of claim 1, wherein forming the second semiconductor layer comprises:
Wherein the second optical guide layer, the second cladding layer, and the second contact layer are sequentially grown on the active layer in an atmosphere containing the H ₂ gas. 6. The method of claim 5, wherein a minimum concentration of impurities to be implanted during the growth of the second contact layer is 1e19 / cm3 or more. 6. The method of claim 5, wherein the concentration of the impurity implanted in the second contact layer is gradually increased in a thickness direction from the lower surface to the upper surface. 6. The method according to claim 5, wherein the concentration of the impurity implanted in the second contact layer is gradually decreased in a thickness direction from the lower surface to the upper surface. 6. The method of claim 5, wherein a concentration of impurities to be implanted during the growth of the second contact layer is the same in the thickness direction from the lower surface to the upper surface.

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