JP4413374B2 - GaN-based light emitting device creation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is for producing a light emitting device composed of a GaN-based compound semiconductor. Ga The present invention relates to a method for producing an N-based light emitting element.
[0002]
[Prior art]
GaN (gallium nitride) is a material belonging to the group III-V nitride semiconductor from the classification of compound semiconductors based on the periodic table, and its crystal structure is a hexagonal wurtzite structure. Other materials belonging to this group III-V nitride semiconductor include aluminum nitride (AlN) and indium nitride (InN). All of these are known as materials having essentially superior characteristics in terms of light emission efficiency compared to materials belonging to the indirect transition type such as SiC, since the energy band structure is a direct transition type.
[0003]
In addition, these mixed crystals (Al, Ga, In) N can change the band gap energy Eg within a wide range from 1.95 to 6.28 eV depending on the mixed crystal ratio. Therefore, there is a possibility that all colors in the visible region from ultraviolet to red can be realized as colored light. Furthermore, features such as a high melting point, high hardness, and high thermal conductivity common to these materials are particularly promising as materials for light-emitting devices because they can provide highly reliable devices with excellent environmental resistance.
[0004]
As described above, the GaN-based compound semiconductor has a sufficient potential as a light emitting material, and particularly has a blue color as the colored light, so that an ultraviolet light emitting diode (LED) can be realized. Therefore, by combining the existing red and green LEDs with this, it is possible to realize a full color display using the LEDs.
[0005]
In general, in manufacturing an LED or LD (laser diode), a substrate having a lattice constant sufficiently high with a light emitting material is required as a substrate to be used in order to obtain a thin film by epitaxial growth. If this requirement is not met, the crystal structure of the thin film is different from the crystal structure of the substrate, and mismatching occurs in the lattice constant, so that the thin film structure tends to be disturbed at the beginning of thin film growth, resulting in reduced luminous efficiency and lifetime. Will be invited.
[0006]
However, in the production of a GaN-based LED, there is no commercially available epitaxial growth substrate in which the lattice constant is matched, and even in a sapphire substrate actually used for growth, the lattice constant is shifted by nearly 15%. For this reason, it is very difficult to grow a high-quality crystal, which has been long in the past, and has not been developed as a light emitting device.
[0007]
Further, in order to grow GaN, the substrate must be heated to about 1000 ° C. However, at this temperature, the vapor pressure of GaN increases, so it is extremely difficult to improve the crystallinity of the GaN film. Furthermore, since there is a problem that GaN cannot form a p-type crystal, it has been more difficult to realize a GaN-based light emitting device.
[0008]
Against this background, in recent years, it has been found that when a GaN film is grown after first forming a thin buffer layer with AlN or GaN on a substrate, the crystallinity is dramatically improved. The crystallinity problem due to lattice mismatch was solved. Further, it has also been found that a p-type GaN film having a low resistance is formed when an electron beam irradiation or a thermal annealing process is performed on a Mg-doped GaN film. As a result, at present, a pn junction of a GaN-based material can be realized, and the above-described mixed crystal film such as InGaN can be obtained.
[0009]
Below, the typical preparation method of GaN-type LED which used InGaN for the active layer is demonstrated. A GaN-based LED is provided as a thin film multi-layer structure. Here, a case where a MOCVD (Metal-Organic Chemical Vapor Deposition) method is employed as a method for forming the thin film will be described.
[0010]
First, in producing a GaN-based LED, ammonia (NH) is formed on a semi-insulating sapphire substrate or a conductive SiC substrate. _Three ) And trimethylaluminum (TMA) are used to grow the AlN buffer layer.
[0011]
Furthermore, trimethylgallium (TMG) and ammonia (NH _Three ) And silane (SiH) _Four ) Is used as a gas source, and a Si-doped n-type GaN layer is grown at a growth temperature of 1050 ° C. Further, TMA is added to the above raw material to grow an n-type AlGaN layer functioning as a cladding layer at a growth temperature of 1050 ° C. And on top of that, trimethylindium (TMI), TMG and NH _Three Is used as a gas raw material, and a non-doped InGaN layer to be an active layer is formed at the same temperature.
[0012]
Further, a p-type AlGaN layer to be the other cladding layer is grown at the same temperature using cyclopentadienyl magnesium (CpMg) as a dopant. Finally, a p-type GaN layer is grown at the same temperature using biscyclopentadienyl magnesium (bCpMg) as a dopant.
[0013]
As described above, the laminated film constituting the LED includes a buffer layer, an n-type low resistance layer, an n-type cladding layer, an active layer, a p-type cladding layer, and a p-type low resistance layer deposited on a sapphire substrate at a low temperature. In general, order.
[0014]
In order to perform patterning to form an electrode after laminating the thin film, ₂ Etc. are deposited on the surface using a plasma CVD apparatus, and then etched and patterned using a photoresist and chemical etching to form an n-type electrode. In this case, up to a part of the n-type GaN is etched, and a metal such as Ti / Al is vapor-deposited on the upper surface to form an n-type electrode. On the other hand, the p-type electrode is formed by evaporating a metal such as Au / Ni on the upper surface of the p-type GaN.
[0015]
As described above, a GaN-based LED using InGaN as an active layer has been established as a manufacturing method, and furthermore, high-luminance light emission can be obtained by forming a light emission center by adding In. There are many on the market. However, in this LED using InGaN as an active layer, the blue-violet light emission satisfies a sufficient practical use. However, when other colors are realized by changing the amount of doping of In, it is at most orange on the long wavelength side. In the present situation, red light emission, which is one of the basic colors of RGB, has not been realized. In other words, light emission of all RGB basic colors by changing the doping rate has not been realized with only LEDs having InGaN as an active layer.
[0016]
However, in recent years, it has been found that GaN-based materials to which phosphorus (P) or arsenic (As) is added are also promising as materials for blue LEDs. GaNP and GaNAs doped with these additives are expected to be capable of emitting a wide range of colors from ultraviolet to red depending on the doping amount of the additive, and to realize light emission of all RGB basic colors.
[0017]
For example, GaNAs can be colored from ultraviolet to red by adding As within 10%, and GaNP can be colored from ultraviolet to infrared by adding P within 15%.
[0018]
[Problems to be solved by the invention]
However, while GaP and GaAs have a small energy gap with a substantially linear change range with respect to the doping amount of P and As, GaNAs and GaNP have an energy gap with respect to the doping amount of P and As as described above. There is a problem that it is difficult to control because the change is large and the form of the change is also non-linear.
[0019]
In the formation of a thin film, it is known that atoms / molecules colliding with the surface of the substrate or the thin film are partially reflected and others remain on the surface. Atoms and molecules staying on the surface are diffused (migrated) by their own energy and the temperature of the substrate, some are re-evaporated (desorbed), and others settle in the potential valley (adsorption). . That is, in order to form a thin film, it is necessary to reduce the desorption of material atoms and molecules, and to perform sufficient migration and adsorption over the entire substrate.
[0020]
However, when forming a film of GaNP or GaNAs by the MOCVD method or the like, there is a problem that P or As is easily detached when the substrate is at a high temperature of about 1000 ° C., and it is difficult to obtain high-quality GaNP or GaNAs. For this reason, there has been a problem that a good quality active layer cannot be obtained and the luminous efficiency is low.
[0021]
The occurrence of this desorption is inconsistent with the crystal structure of GaNP or GaNAs and the crystal structure of the sapphire substrate or the like, and thus is in a relatively high temperature state of about 1000 ° C. as described above even if a buffer layer is interposed. The reason is that P and As cannot remain in place for a long time on the substrate. In the following, migration refers to the state of surface adsorption required to obtain a desired mixed crystal such as GaNP or GaNAs.
[0022]
The present invention has been made in view of the above, and uses laser light irradiation in combination with materials such as GaNP and GaNAs that cannot obtain a good quality mixed crystal thin film when the crystal substrate is at a high temperature. Therefore, even when the crystal substrate is at a low temperature, decomposition and migration of the source gas can be promoted. Ga An object of the present invention is to provide a method for producing an N-based light emitting device.
[0023]
[Means for Solving the Problems]
To achieve the above objective, this The present invention relates to a GaN-based light emitting device creating apparatus for creating a GaN-based light emitting device as a thin film laminated structure by a vapor phase growth method, and when adding a raw material to be mixed with gallium (Ga) to the Ga, a thin film forming substrate A laser beam irradiation means for irradiating a laser beam is provided on the top.
[0024]
According to the present invention, decomposition of the raw material gas mixed with Ga and migration onto the thin film forming substrate can be performed by light energy by laser light irradiation.
[0025]
Also, this The present invention relates to a method for producing a GaN-based light-emitting element in which a GaN-based light-emitting element is formed as a thin film laminated structure by vapor deposition, and a raw material for heating a thin film-forming substrate to a predetermined temperature to be mixed with gallium (Ga). When adding to Ga, the thin film forming substrate is irradiated with laser light.
[0026]
According to the present invention, the decomposition of the source gas mixed with Ga and the migration onto the thin film forming substrate can be performed by the light energy by the laser light irradiation as well as the thermal energy given by the heating of the thin film forming substrate. .
[0027]
Also, this The invention The above invention In the GaN-based light emitting device fabrication method, the raw material contains arsenic (As) or phosphorus (P) decomposed by the laser light irradiation.
[0028]
According to the present invention, gas decomposition of As and P, which has been difficult to achieve a sufficient amount of gas decomposition only by heating the conventional thin film formation substrate, is promoted by the combined use of laser light irradiation. be able to.
[0029]
Also, this The invention The above invention In the method for producing a GaN-based light emitting device, the thin film having a crystal structure mixed with Ga contains arsenic (As) or phosphorus (P) migrated by the laser light irradiation.
[0030]
According to the present invention, it is possible to promote the migration of As and P, which have been difficult to achieve a sufficient migration only by heating the conventional thin film formation substrate, by the combined use of laser light irradiation.
[0031]
Also, this The invention The above invention In the GaN-based light emitting device fabrication method, the predetermined temperature is in the range of 900 ° C. to 400 ° C.
[0032]
According to the present invention, even when it is difficult to achieve sufficient migration of the raw material by the conventional heating of the thin film forming substrate at a high temperature, the migration is promoted by the combined use of laser light irradiation. Therefore, the heating temperature of the thin film forming substrate can be set to a range of 900 ° C. to 400 ° C., which is lower than the conventional growth temperature which was about 1000 ° C.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a GaN-based light-emitting element creating apparatus and a GaN-based light-emitting element creating method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.
[0034]
Embodiment 1 FIG.
First, a GaN-based light emitting device creation apparatus and a GaN-based light emitting device creation method according to the first embodiment will be described. In particular, the first embodiment shows a GaN-based light emitting device creation apparatus when a thin film is formed by MOCVD. FIG. 1 is a diagram illustrating a schematic configuration of a GaN-based light emitting device creation apparatus according to the first embodiment. A GaN-based light emitting device producing apparatus 10 shown in FIG. 1 includes a reactor 20 serving as a growth chamber in which a thin film is formed, a gas introduction system 30 for introducing various source gases into the reactor 20, a laser light source 40, A laser oscillation control unit 42 that controls the oscillation of the laser light source 40, an RF coil control unit 44 that controls the RF coil 22, and a temperature measurement unit 46 that measures the temperature of the susceptor 24 or the substrate 9 placed thereon. , And is configured. In the drawing, a vacuum exhaust system or the like normally required in the reactor 20 and the gas introduction system 30 is omitted.
[0035]
Here, the reactor 20 is a two-flow type reactor in which the source gas is supplied from the gas introduction system 30 via the line 1 and the line 2 and has a structure suitable for forming a GaN-based thin film conventionally used. It is. Further, the RF coil 22 can heat the susceptor 24 with a high frequency current given by the RF coil control unit 44. Instead of the RF coil 22 and the RF coil controller 44, a heater and a heater controller provided in the susceptor 24 may be used.
[0036]
The temperature measurement unit 46 processes an infrared radiation thermometer capable of measuring the temperature of the substrate 9 and the like from the outside of the reactor 20 and a signal obtained from a thermocouple directly connected to a measurement object such as the substrate 9. Circuit.
[0037]
The laser light source 40 is a light source capable of oscillating high-energy ultraviolet light, and uses, for example, an ArF laser (193 nm) with 10 W output. On / off control of the ArF laser and scan control described later are controlled by the laser oscillation control unit 42. The laser light source 40 is fixed outside the reactor 20 and at a position where the laser beam irradiation destination is on the substrate 9. Since the reactor 20 is generally covered with a bell jar made of a glass material such as quartz, such a configuration that enables light irradiation from the outside to the inside can be easily realized. Further, even with a stainless steel bell jar, it is easy to secure a laser light incident region such as by providing a glass viewport.
[0038]
The gas introduction system 30 has the same configuration as a gas line used in the conventional MOCVD method. That is, it is composed of the above-described two lines, Line 1 and Line 2, and the hydrogen gas supplied from the hydrogen gas cylinder 38 and the hydrogen purifier 37 is used as the raw material carrier gas, and the mass flow controller (MFC) 32 uses it. This is a line system for transporting a certain amount of organometallic gas obtained by bubbling an organometallic raw material with the organometallic cylinder 34 or a vapor phase raw gas obtained by the raw gas cylinder 36 to the reactor 20 while controlling the flow rate.
[0039]
Next, a method for producing a GaN-based light emitting element realized by the GaN-based light emitting element producing apparatus will be described. FIG. 2 is a flowchart showing the LED creation procedure executed by the GaN-based light emitting device creation method according to the first embodiment. FIG. 3 is an LED cross-sectional view for explaining an LED created according to the flowchart shown in FIG. Here, in particular, a procedure for producing an LED having an active layer of GANP will be described as an example.
[0040]
First, a crystal substrate such as a sapphire substrate, SiC or silicon substrate is placed on the susceptor 24. Here, a sapphire substrate is used as the crystal substrate. In this state, the temperature of the sapphire substrate 51 is maintained at 640 ° C. by the oscillation of the RF coil 22 (step S101).
[0041]
When the temperature measuring unit 46 detects that the sapphire substrate 51 has reached 640 ° C., the formation of the GaN buffer layer is started (step S102). The GaN buffer layer 52 is formed on the sapphire substrate 51 as a crystal structure having a thickness of 50 mm by supplying about 200 sccm of dimethylhydrazine (DMH) and about 20 sccm of TMG from the gas introduction system 30 to the reactor 20. (FIG. 3A).
[0042]
Then, the substrate temperature is maintained at 850 ° C. by the oscillation of the RF coil 22 (step S103). When the temperature measuring unit 46 detects that the sapphire substrate 51 has reached 640 ° C., laser irradiation is next performed by the laser light source 40 (step S104). The laser irradiation at this stage is NH described later at the substrate temperature of about 850 ° C. _Three Since the energy is insufficient to promote the decomposition of the source gas such as, it plays a role of assisting it.
[0043]
In this state, an n-type GaN layer is formed next (step S105). The n-type GaN layer 53 includes TMG of about 20 sccm and NH of about 1500 sccm. _Three And about 2 sccm of SiH _Four Is grown on the GaN buffer layer 52 as described above to obtain a GaN layer having a thickness of 2 μm doped with Si (FIG. 3B).
[0044]
Next, an n-type AlGaN layer functioning as a cladding layer is formed (step S106). The n-type AlGaN layer 54 includes TMG of about 20 sccm and NH of about 1500 sccm. _Three And about 2 sccm of SiH _Four Then, a TMA source gas of about 5 sccm is grown on the n-type GaN layer 53 to obtain an AlGaN layer having a thickness of 1000 た doped with Si (FIG. 3C).
[0045]
Next, non-doped GaN that becomes the active layer _1-x P _x A layer (where 0 <x <1) is formed (step S107). This GaN _1-x P _x The layer 55 includes TMG of about 20 sccm and NH of about 1500 sccm. _Three And about 500 sccm of phosphine (PH _Three ) Is grown on the n-type AlGaN layer 54 as described above to obtain a GaNP layer having a thickness of about 10 nm (FIG. 3D).
[0046]
At this time, the laser light emitted from the laser light source 40 is scanned in a certain range so as to irradiate the entire surface of the substrate. As a result, NH _Three And PH _Three Gas decomposition is promoted, and migration of P to the substrate surface can be promoted. That is, a lot of PH is generated by laser light irradiation. _Three Is decomposed and a sufficient amount of P atoms / molecules can be supplied in a certain region on the substrate surface, while the substrate temperature is lower (850 ° C.) than the conventional set temperature (about 1000 ° C.), These P atoms and molecules do not desorb from the substrate, and migration is also achieved in which the underlying crystal structure is interrupted by laser energy. Thereby, a GaNP layer having a sufficiently large thickness of 10 nm can be obtained.
[0047]
Subsequently, a p-type AlGaN layer functioning as the other cladding layer is formed (step S108). The p-type AlGaN layer 56 includes TMG of about 20 sccm and NH of about 1500 sccm. _Three And a source gas of about 3 sccm of cyclopentadienylmagnesium (CpMg) and about 5 sccm of TMA. _1-x P _x It is grown on the layer 55 and obtained as an AlGaN layer having a thickness of 1000 mm doped with Mg (FIG. 3E).
[0048]
Finally, a p-type GaN layer is formed (step S109). This p-type GaN layer 57 includes TMG of about 20 sccm and NH of about 1500 sccm. _Three Then, a source gas of about 3 sccm of biscyclopentadienylmagnesium (bCpMg) is grown on the p-type AlGaN layer 56 to obtain a GaN layer having a thickness of 1000 mm doped with Mg (FIG. 3F). ).
[0049]
Then, after laminating the thin film, in order to perform patterning for forming an electrode, SiO ₂ And the like are deposited on the surface using a plasma CVD apparatus, and then etched and patterned using a photoresist and chemical etching to form an n-type electrode (step S110).
[0050]
FIG. 4 is a cross-sectional view of the LED structure after electrode formation. As shown in FIG. 4, up to a part of the n-type GaN layer 53 is etched from the above-described laminated film, and a metal such as Ti / Al / Au is deposited on the upper surface thereof, thereby forming an n-type electrode 62. Is done. On the other hand, the p-type electrode 61 is formed by evaporating a metal such as Au / Ni on the upper surface of the p-type GaN layer 57 described above.
[0051]
When a voltage was applied to the LED thus produced to examine light emission, an extremely strong light emission peak was observed in the vicinity of a bandwidth of 400 nm at an applied voltage of 4V. Other peaks were not observed. That is, it was confirmed that a high-intensity ultraviolet LED was produced.
[0052]
The laser beam irradiation described above may be a continuous wave or a pulse wave. In the case of a continuous wave, the substrate heated by the RF coil 22 in consideration of the temperature rise of the material due to the continuous irradiation of the laser beam. The temperature can be set small.
[0053]
Furthermore, in the apparatus configuration shown in FIG. 1, only one laser light source is used, but two laser light sources for gas decomposition and migration may be provided. FIG. 5 is an explanatory diagram for explaining laser irradiation when two laser light sources are provided. In FIG. 5, the laser light source 72 is for migration, and the laser light source 74 is for gas decomposition. For example, as shown in FIG. 5, a laser light source 74 is installed at a position where the upper surface region 74 of the substrate 9 is irradiated, and the laser light source 74 is accompanied by a scanning mechanism 76 based on rotation control of a prism, a reflection mirror, a diffraction grating, or the like. Thus, it is installed at a position where the entire surface of the substrate 9 is irradiated.
[0054]
As described above, according to the GaN-based light emitting device fabrication apparatus and the GaN-based light emitting device fabrication method according to the first embodiment, among the GaN-based compound semiconductors, additives such as As and P that are difficult to migrate. In a method for producing a GaN-based light emitting device according to the MOCVD method for producing a mixed crystal of _Three When the vapor phase source gas such as is irradiated with the laser beam on the substrate 9, decomposition of the vapor phase source gas is promoted by the laser beam energy, so that many mixed crystal constituent molecules are formed on the substrate. 9, and the temperature of the substrate 9 is set to a relatively low temperature, so that it is possible to avoid the detachment of the mixed crystal constituent molecules due to the high temperature state of the substrate 9.
[0055]
In particular, when attempting to obtain a mixed crystal in which As or P or the like, which could not be sufficiently migrated under conventional substrate temperature conditions, is added to GaN, gas decomposition is promoted by the laser irradiation described above. The migration to the substrate 9 can be promoted by the laser light energy. Thereby, a good-quality thin film of GaNAs or GaNP can be formed. That is, it is possible to precisely control the doping amount of As and P, and it is possible to efficiently create a full-color display or a white LED using LEDs composed only of GaNAs or GaNP.
[0056]
Embodiment 2. FIG.
Next, a GaN-based light emitting device creating apparatus and a GaN-based light emitting device creating method according to the second embodiment will be described. In particular, the second embodiment shows a GaN-based light emitting device fabrication apparatus in the case where a thin film is formed by a gas source MBE (Molecular Beam Epitaxy) method. FIG. 6 is a diagram illustrating a schematic configuration of a GaN-based light emitting device creation apparatus according to the second embodiment.
[0057]
The GaN-based light emitting device creating apparatus 110 shown in FIG. 6 includes a reactor 120 serving as a growth chamber in which a thin film is formed, a laser light source 140, a laser oscillation control unit 142 that controls oscillation of the laser light source 140, and a heater 122. A heater control unit 144 for controlling, and a temperature measurement unit 146 for measuring the temperature of the susceptor 124 or the substrate 109 installed thereon are configured. In the figure, a vacuum exhaust system or the like that is normally required is omitted.
[0058]
Here, similarly to the conventional gas source MBE apparatus, the reactor 120 is provided with a plurality of molecular beam cells 152 for charging the raw material. Here, Ga or Al is charged as the raw material, and in particular, n Disilane or Si is loaded as a dopant for forming a type thin film, and Mg is loaded as a dopant for forming a p type thin film.
[0059]
Release of the molecular beam of the raw material from these molecular beam cells 152 is performed by heating by the heater 156 and is selectively switched by opening and closing the shutter 154. Note that radicalized nitrogen is emitted from the plasma gun 150.
[0060]
Further, the temperature measurement unit 146 processes signals obtained from an infrared radiation thermometer capable of measuring the temperature of the substrate 109 and the like from the outside of the reactor 120 and a thermocouple directly connected to a measurement object such as the substrate 109. Circuit.
[0061]
The laser light source 140 is the same light source as that in the first embodiment, and the laser oscillation control unit 142 performs on / off control and scan control of the laser light source 140. The laser light source 140 is fixed outside the reactor 120 and at a position where the laser beam irradiation destination is on the substrate 109.
[0062]
Also in the GaN-based light emitting device manufacturing apparatus according to the second embodiment having the above-described configuration, the same substrate temperature control and laser light irradiation as in the case shown in the first embodiment are performed. That is, NH _Three When the n-type GaN layer is formed at a growth temperature of 850 ° C. lower than the conventional growth temperature using Ga and Ga as source gases, the substrate 109 is irradiated with laser light. In particular, NH _Three , PH _Three When forming the GaNP layer using Ga and Ga as source gases, the entire surface of the substrate 109 is irradiated with laser light. Since the other thin film forming procedures are the same as those in the prior art, the description thereof is omitted here.
[0063]
As described above, according to the GaN-based light-emitting element manufacturing apparatus and the GaN-based light-emitting element manufacturing method according to the second embodiment, among the GaN-based compound semiconductors, particularly additives such as As and P that are difficult to migrate Also in the GaN-based light emitting device creation method according to the gas source MBE method for creating a mixed crystal of the above, it is possible to enjoy the same effect as the effect shown in the first embodiment.
[0064]
Embodiment 3 FIG.
Next, a GaN-based light emitting device creation apparatus and a GaN-based light emitting device creation method according to Embodiment 3 will be described. In particular, the third embodiment shows a GaN-based light emitting device producing apparatus in the case where a thin film is formed by a plasma CVD method. FIG. 7 is a diagram illustrating a schematic configuration of the GaN-based light emitting device creation apparatus according to the third embodiment.
[0065]
A GaN-based light emitting device creation apparatus 210 shown in FIG. 7 includes a reactor 220 serving as a growth chamber in which a thin film is formed, a laser light source 240, a laser oscillation control unit 242 that controls oscillation of the laser light source 240, and a heater 222. A heater control unit 244 for controlling, and a temperature measurement unit 246 for measuring the temperature of the susceptor 224 or the substrate 209 installed thereon are provided. In the figure, a vacuum exhaust system or the like that is normally required is omitted.
[0066]
Here, like the conventional plasma CVD apparatus, the reactor 220 is provided with an electrode 254 which functions as a source gas introduction line and serves as one electrode for generating plasma, A high frequency voltage is applied between the functioning susceptor 224 and the RF oscillator 252, so that plasma is generated on the upper surface of the substrate 109.
[0067]
Note that the source gas has the same composition as that of the first embodiment. Therefore, in FIG. 7, a raw material gas supply line similar to that of the gas introduction system 30 shown in FIG. 1 is required, but the illustration thereof is omitted here.
[0068]
The temperature measuring unit 246 processes signals obtained from an infrared radiation thermometer capable of measuring the temperature of the substrate 209 and the like from the outside of the reactor 220 and a thermocouple directly connected to a measurement object such as the substrate 209. Circuit.
[0069]
The laser light source 240 is the same light source as in the first embodiment, and the laser oscillation control unit 242 performs on / off control and scan control of the laser light source 240. The laser light source 240 is fixed outside the reactor 220 and at a position where the laser beam irradiation destination is on the substrate 209.
[0070]
Also in the GaN-based light emitting device fabrication apparatus according to the third embodiment having the above-described configuration, the same substrate temperature control as that in the first embodiment and laser light irradiation with the same timing are performed. That is, TMG, NH _Three And SiH _Four When forming an n-type GaN layer at a growth temperature of 850 ° C. lower than the conventional growth temperature, the substrate 209 is irradiated with laser light. Especially TMG, NH _Three And PH _Three When forming a GaNP layer using as a source gas, the entire surface of the substrate 209 is irradiated with laser light. Since the other thin film forming procedures are the same as those in the prior art, the description thereof is omitted here.
[0071]
As described above, according to the GaN-based light-emitting element creating apparatus and the GaN-based light-emitting element creating method according to the third embodiment, among the GaN-based compound semiconductors, particularly additives such as As and P that are difficult to migrate Also in the GaN-based light emitting device fabrication method according to the plasma CVD method for creating a mixed crystal of the above, the same effect as the effect shown in the first embodiment can be enjoyed.
[0072]
Note that the plasma CVD method is characterized in that gas decomposition is performed by using plasma activation energy. Therefore, the heater 222 is not necessary for promoting gas decomposition, but energy for promoting migration. It is necessary as a means to give Therefore, in the GaN-based light emitting device fabrication apparatus according to the third embodiment, the laser light irradiation by the laser light source 240 described above may be performed only when the migration is promoted.
[0073]
In the first to third embodiments described above, the case where the active layer is made of GaNP or GaNAs has been described as an example. It goes without saying that you can do it. In addition to the above-described thin film forming methods such as MOCVD, the present invention can also be applied to chloride-based vapor phase growth using chloride such as gallium chloride or hydride as a raw material.
[0074]
【The invention's effect】
As explained above this According to the invention, since the laser beam irradiation means for irradiating the thin film forming substrate with the laser beam is provided, the decomposition of the source gas mixed with Ga and the migration onto the thin film substrate are performed by the laser beam irradiation. It can be performed by light energy, and produces an effect that a GaN multi-element mixed crystal that cannot be realized by high-temperature heating of a thin film formation substrate can be produced.
[0075]
Also, this According to the invention, decomposition of the source gas mixed with Ga and migration onto the thin film forming substrate can be performed by light energy by laser light irradiation as well as thermal energy given by heating of the thin film forming substrate. Even for a raw material that is difficult to be mixed with Ga due to high-temperature heating of the thin film forming substrate, the mixed crystal can be realized by reducing the heating of the thin film forming substrate.
[0076]
Also, this According to the present invention, the gas decomposition of As and P, which has been difficult to achieve a sufficient amount of gas decomposition only by heating the conventional thin film formation substrate, is promoted by the combined use of laser light irradiation. There is an effect that can be.
[0077]
Also, this According to the present invention, the migration of As and P, which could not be migrated due to high-temperature heating of the thin film formation substrate and difficult to be mixed with Ga, was achieved by the combined use of laser light irradiation. Since such a raw material can be promoted, there is an effect that the mixed crystal can be realized by reducing the heating of the thin film forming substrate.
[0078]
Also, this According to the invention, even when it is difficult to achieve sufficient migration of the raw material by heating the thin film forming substrate at a conventional high temperature, the migration can be promoted by the combined use of laser light irradiation. Therefore, there is an effect that the heating temperature of the thin film forming substrate can be set in the range of 900 ° C. to 400 ° C., which is lower than the conventional growth temperature of about 1000 ° C.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a GaN-based light emitting device creation apparatus according to a first embodiment.
FIG. 2 is a flowchart showing a thin film creation procedure executed by the GaN-based light emitting device creation method according to the first embodiment;
FIG. 3 is an LED cross-sectional view for explaining an LED produced by the GaN-based light emitting device production method according to the first embodiment.
4 is a cross-sectional view of the LED structure after electrode formation in the GaN-based light emitting device fabrication method according to Embodiment 1. FIG.
5 is an explanatory diagram for explaining laser irradiation in the case where two laser light sources are provided in the GaN-based light emitting device manufacturing method according to Embodiment 1. FIG.
FIG. 6 is a diagram showing a schematic configuration of a GaN-based light emitting device creation apparatus according to a second embodiment.
FIG. 7 is a diagram showing a schematic configuration of a GaN-based light emitting device creation apparatus according to a third embodiment.
[Explanation of symbols]
9, 109, 209 substrate
10, 110, 210 GaN-based light emitting device creation device
20, 120, 220 reactor
22 RF coil
24,124,224 Susceptor
30 Gas introduction system
34 Organic metal cylinder
36 Raw material gas cylinder
37 Hydrogen Purifier
38 Hydrogen gas cylinder
40, 72, 74, 140, 240 Laser light source
42, 142, 242 Laser oscillation controller
44 RF coil controller
46,146,246 Temperature measurement unit
51 Sapphire substrate
52 GaN buffer layer
53 n-type GaN layer
54 n-type AlGaN layer
55 GaN _1-x P _x layer
56 p-type AlGaN layer
57 p-type GaN layer
61 p-type electrode
62 n-type electrode
76 Scanning mechanism
122,156,222 heater
144,244 Heater control unit
150 Plasma Gun
152 molecular beam cell
154 shutter
252 RF oscillator
254 electrodes

Claims (3)

In a GaN-based light-emitting element creation method for creating a GaN-based light-emitting element as a thin film laminated structure by vapor deposition,
Heat the thin film forming substrate to a predetermined temperature,
When the raw material containing arsenic (As) or phosphorus (P) mixed with gallium (Ga) is added to the Ga, the raw material is decomposed by irradiating the thin film forming substrate with laser light. A method for producing a GaN-based light emitting device. The Ga and disordered thin films is, GaN-based light emitting device creation method according to claim 1, characterized in that it comprises an arsenic (As) or phosphorus (P), which is migrated by the irradiation of the laser beam. The method for producing a GaN-based light emitting device according to claim 1 or 2 , wherein the predetermined temperature is in a range of 900 ° C to 400 ° C.

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