JP7082390B2 - Deep ultraviolet light emitting device and its manufacturing method - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Law 1. Release date February 4, 2017 Release method Uploaded to the campus server owned by Kochi University of Technology System Engineering Group (currently not open to the public) 2. Meeting name Master's thesis hearing Venue Kochi University of Technology (185 Miyanoguchi, Tosayamada-cho, Kami-shi, Kochi) Date February 5, 2017 3. Meeting name The 64th Japan Society of Applied Physics Spring Academic Lecture Venue 1-1-1 Minatomirai, Nishi-ku, Yokohama-shi, Kanagawa Pacifico Yokohama Date March 17, 2017

The present invention relates to a deep ultraviolet light emitting device using an oxide, specifically a GaO-based or AlGaO-based oxide, and a method for producing the same.

In recent years, there has been an increasing demand for thinning of metal or metal compound materials. A thin film is one of the material forms, and generally refers to a film material having a thickness of 10 μm or less. Thin film materials are known to have various properties such as electrical properties such as specific resistance, thermal properties such as thermal conductivity, mechanical properties such as wear resistance, and light emission properties, and are used for various electronic devices. Many are applied.

Nitride such as GaN, which is the main material of blue light emitting diodes, and arsenide compounds such as GaAs, which is the main material of red semiconductor lasers, are widely known as thin film materials having light emitting characteristics. It is also possible to do. Oxides are generally stable on earth and have the advantage of high electrical resistance. However, since it has both covalent and ionic bonding properties, its resistance to disturbance factors such as heat and deformation is inferior to that of nitrides, so high-level thin film production control is required during production. Therefore, it is said that mass production is difficult.

On the other hand, many of the devices currently put into practical use as means for manufacturing thin film materials are thin film manufacturing devices using vacuum. However, it is reported that a device using a vacuum requires a huge amount of energy, and about 20% of the energy used in factories and the like is consumed for operating a vacuum pump.

Therefore, a system capable of forming a film under atmospheric pressure is desired, but this occurs because a) generation of convection due to heat and b) the amount of atoms present in space is overwhelmingly larger than that of vacuum. There is a solution problem such as an unexpected complex reaction, and conventionally, thin film production by an atmospheric pressure process has a problem that it is difficult to improve the quality and mass production.

As a method for solving the shortcomings of the conventional atmospheric pressure process, a mist CVD method (Mist Chemical Vapor Deposition) has been proposed. This method is a method in which a solution containing a main component is atomized into a mist and supplied to the base material in a mist state. By controlling the supply conditions of mist and designing the reactor, it is possible to produce a thin film with high uniformity so that thermal convection and side reactions can be almost ignored. Further, the mist CVD method has advantages that the environmental load is small and the operating cost is low.

By the way, Patent Document 1 and Patent Document 2 describe techniques for manufacturing a light emitting film using an oxide by a manufacturing process under atmospheric pressure. Patent Document 1 and Patent Document 2 relate specifically to a technique for producing a deep ultraviolet light emitting film by using gallium oxide and a mist CVD method.
1) The light emitting layer that emits deep ultraviolet light contains an oxide containing at least gallium. 2) The light emitting layer is a first layer and a second layer whose main component is a material different from that of the first layer. The layers have a quantum well structure in which at least one layer is alternately laminated. 3) One of the main components of the first layer and the second layer is an oxide containing at least aluminum. 4 ) It is described that the main components of the first layer and the second layer are oxides having a corundum structure, respectively. 5) The light emitting layer is formed by a mist CVD method.

JP-A-2017-52855 Japanese Unexamined Patent Publication No. 2017-54654

By stacking multiple layers of thin films made of different substances using thin film growth technology, the effect of confining electrons (carriers) and holes (holes) in the thin layer, and the effect of confining electrons and holes in one layer. Due to these effects and the quantum effect on phonons, it is possible that even oxides that are still under development compared to nitrides and arsenic compounds can be applied to light-emitting film materials. It is believed that there is.

Specifically, it has been studied to form a light emitting film made of an oxide by constructing a multiple quantum well structure using a mist CVD method. The multiple quantum well structure is a structure in which materials with different band gaps are alternately laminated to form an energetic well, and carriers can be confined. By constructing this structure, electrons and holes can be reunited. The binding probability is increased, and as a result, the emission efficiency is improved. Therefore, if high crystallization of the oxide thin film is possible, it is considered that the oxide light emitting film can be put into practical use.

The above-mentioned Patent Documents 1 and 2 disclose the production of a deep ultraviolet light emitting film by using the mist CVD method, but only comprehensively describe the conditions under which the deep ultraviolet light emitting film can be produced. No specific structure or manufacturing method of the deep ultraviolet light emitting film having practical light emitting properties is disclosed. Therefore, if a person skilled in the art wants to obtain a deep ultraviolet light emitting film having practical light emitting characteristics based on Patent Documents 1 and 2, further research and accumulation of a large number of experiments are required.

An object of the present invention is to provide a specific structure and a manufacturing method for realizing a deep ultraviolet light emitting device provided with a deep ultraviolet light emitting film having a practical light emitting intensity.
The deep ultraviolet light emitting element adopted in the present invention for achieving the above object has a buffer layer composed of (Al _x Ga _1-x ) ₂ O ₃ (provided, 0 <x ≦ 1) disposed on a substrate. , N (N is a natural number) light emitting layer composed of (Al _w Ga _1-w ) ₂ O ₃ (where 0 ≦ w <1) arranged on the buffer layer, and each of the N light emitting layers. It was arranged on the (N-1) barrier layer composed of (Al _y Ga _1-y ) ₂ O ₃ (provided that 0 <y ≦ 1) arranged between them and the uppermost light emitting layer. (Al _z Ga _1-z ) ₂ O ₃ (where 0 <z ≦ 1) is included, the light emitting layer has a thickness of 0.1-10 nm, and the buffer layer, the barrier layer, and the barrier layer are included. It is characterized in that the thickness of the cap layer is set to be equal to or thicker than the thickness of the light emitting layer, and the band gap is 4.8-8.7 eV.

The bandgap of α-Ga ₂ O ₃ calculated from the permeability measurement is around 5.3 eV (estimated from the Elliott equation is 5.6 eV: PHYSICAL REVIEW MATERIALS 1,024604 (2017) “Band gap of corundumlike α-Ga”. ₂ O ₃ determined by absorption and apoptosis ”), but it is desirable to set the emission wavelength to a value obtained by subtracting the loss such as exciton binding energy from the band gap. The specific emission wavelength in the present invention is in the range of about 140-260 nm.

When a plurality of light emitting layers and barrier layers are formed, the values of w for determining the Al: Ga ratio of the light emitting layer and y for determining the Al: Ga ratio of the barrier layer are each light emitting layer and each barrier layer. Although different values may be set for each, in order to make uniform light emission and to obtain a highly efficient product, w of each light emitting layer is set to the same value and each barrier layer is set to the same value. The same value may be set for y as well.

The band gap of the barrier layer sandwiching the light emitting layer can be any combination. Further, each layer of the buffer layer, the barrier layer, and / or the cap layer can be composed of a plurality of layers having different composition ratios of Al and Ga, and the composition can be changed so as to improve the crystallinity. .. In particular, the crystallinity of the light emitting layer can be enhanced by using a gradient buffer layer that continuously changes the Al: Ga composition ratio.

In this case, in particular, when the barrier layer adjacent to the light emitting layer is composed of a plurality of layers, y = y1, y2, ... The number of layers having an Al: Ga ratio may be increased.

The light emitting layer can be Ga ₂ O ₃ (that is, w = 0).

Further, the deep ultraviolet light emitting device according to the present invention is characterized in that the base material has a corundum structure. The base material is generally a flat plate-shaped substrate, but a substrate having a curved shape or a three-dimensional shape is also possible.

The method for manufacturing a deep-ozone light-emitting element adopted in the present invention for achieving the above object is a method for manufacturing a deep-ozone light-emitting element by forming a deep-ozone light-emitting film under atmospheric pressure using a thin film manufacturing apparatus. The deep ultraviolet light emitting film is disposed on a buffer layer composed of (Al _x Ga _1-x ) ₂ O ₃ (where 0 <x ≦ 1) and a buffer layer (Al _w Ga _1-w ). ) ₂ O ₃ (where 0 ≤ w <1) is arranged between N (N is a natural number) light emitting layer and each of the N light emitting layers (Al _y Ga _1-y ) ₂ O ₃ (However, 0 <y ≦ 1) (N-1) barrier layers and (Al _z Ga _1-z ) ₂ O ₃ (provided, 0 <z ≦) disposed on the uppermost light emitting layer. The thin film manufacturing apparatus includes a cap layer made of 1), a mist generating means for atomizing a raw material solution to generate a raw material mist, and a transport gas introducing unit into which a transport gas for transporting the raw material mist is introduced. A raw material supply device including a mist sending section for delivering raw material mist, a mist introducing section for introducing raw material mist, a reaction section having a fine channel structure in which a base material is arranged, and a base material. A transport path connecting a film forming device having a heating means for heating and a discharging section for discharging exhaust gas, and a mist sending section of a raw material supply device and a mist introducing section of the film forming device. Includes a transport path, with a diluting gas introduction section, into which the diluting gas is introduced.
The step of forming the buffer layer, the barrier layer, or the cap layer on the base material is a mist generation step of atomizing a raw material solution in which a Ga-containing raw material and an Al-containing raw material are dissolved to generate a raw material mist, and a mist flow containing the raw material mist. In the transfer process of transporting Includes a film forming process in which the raw materials to be deposited are deposited in a mixed crystal state.
At the stage of forming the light emitting layer on the base material, a mist generation step of atomizing a raw material solution in which a Ga-containing raw material and an Al-containing raw material are dissolved to generate a raw material mist in a raw material supply device, and a mist flow containing the raw material mist are transported. A raw material containing Al and at least Ga on the base material by a thermochemical reaction in which the mist flow introduced into the film forming apparatus is brought into contact with the heated substrate in the reaction section. It is characterized by including a film forming step of depositing in a mixed crystal state.

Further, in the method of the present invention, the temperature of the base material is controlled so that the raw material mist causes the Leidenfrost phenomenon in the reaction portion in the film forming step. It is preferable to appropriately design the configuration of the film forming apparatus so as to positively cause the Leidenfrost phenomenon.

The method of the present invention further includes the thin film manufacturing apparatus including two or more raw material feeders, and further includes a mixer for mixing raw material mist delivered from each of the plurality of raw material feeders, and the transport path. Is a first transport path that connects each mist delivery section of the plurality of raw material feeders to the mixer, and is a first transport path having a dilute gas introduction section into which the diluting gas is introduced, and a mixer. The step of forming the light emitting layer, the buffer layer, the barrier layer, or the cap layer on the base material is to supply one of the raw materials, while including a second transport path connecting the mist introduction portion of the film forming apparatus. The first mist generation step of atomizing the raw material solution in which the Ga-containing raw material is dissolved in the vessel to generate the first raw material mist, and the second raw material solution in which the Al-containing raw material is dissolved in the other one raw material feeder are atomized. In the second mist generation step of producing the raw material mist, the first mist flow containing the first raw material mist and the second mist flow containing the second raw material mist are transferred to the mixer through the first transport path and mixed. The mist mixing step, the transfer step of transporting the mixed mist flow obtained by mixing the first mist flow and the second mist flow to the film forming device through the second transport path, and the mixed mist flow introduced into the film forming device. It is possible to include a film forming step of contacting the heated substrate in the reaction section and depositing the Ga-containing raw material and the Al-containing raw material on the substrate in a mixed crystal state by a thermochemical reaction.

In the method, the light emitting layer can be Ga ₂ O ₃ (that is, w = 0).

In the method of the present invention, in order to form a film having a desired composition ratio, as described above, a raw material solution in which an Al source and a Ga source are mixed may be prepared and film formation may be performed. The use of a feedstock makes it easy to predict or design complex reactions and compositions. Further, although the film forming apparatus may be designed to be compatible with a continuous system, it is recommended to design as described above for the purpose of eliminating the influence of impurities and disturbance.

In the method of the present invention, the transport path further includes a support gas introduction section into which a support gas for improving the reactivity is introduced, and the transport step further includes a support gas for improving the reactivity of the raw material mist in the middle thereof. A support gas mixing step for mixing can be further included.

It is also possible to use the second raw material supply device as a supply source of the support gas, and it is also conceivable to use a reaction support agent such as NH ₃ as a mist and supply it to the reactor.

Further, in the method of the present invention _, the supporting gas can be an O3 gas.

Further, in the method of the present invention, a substrate cleaning step of cleaning the surface of the substrate with an organic solvent, an organic acid _, or an O3 gas can be further included prior to the film forming step.

The substrate cleaning step may include both an organic cleaning step of cleaning with an organic solvent or an organic acid and an ozone cleaning step of cleaning with an _O3 gas. In this case, it is desirable to first perform the organic cleaning step and then the ozone cleaning step.

According to the deep ultraviolet light emitting device according to claim 1, a light emitting layer and a buffer layer, a barrier layer, and a cap layer having a thickness higher than this are alternately laminated to form a multiple quantum well structure, which is practical. It is possible to exhibit various light emission characteristics. Further, since the band gap is 4.8-8.7 eV, it is possible to obtain a deep ultraviolet light emitting device having a light emitting wavelength in the range of about 140-260 nm.

As shown by the measurement results described later, the deep ultraviolet light emitting element of the present invention has been confirmed to emit light in the visible light region by the camera, but as can be seen from the CL measurement results of FIG. 5 (A), it is visible. In the light region (1.6 eV to 3 eV), its intensity is hardly confirmed, and it is understood that the light emission in the deep ultraviolet region is overwhelmingly strong. At the same time, there is a possibility that the light emitted from the base material may be emitted under the condition that the light emitted from the base material cannot be completely removed. However, as can be seen from the experimental results described later, it is understood that the light emission of the present invention is certainly not derived from the base material but from the light emitting layer and the materials related thereto.

Further, by controlling each value of w, x, y, and z, it is possible to appropriately set the emission wavelength. The emission wavelength can also be controlled by adjusting the thickness of each layer. Specifically, when the thickness of the light emitting layer is reduced, the emission wavelength can be shifted to the short wavelength side due to the quantum size effect. In addition, by appropriately setting the ratio of Al in the light emitting layer, it is possible to make a transition to a shorter wavelength side. As a result, the deep ultraviolet light emitting device based on the present invention can acquire a band gap of as high as about 8.7 eV and realize short wavelength ultraviolet light emission of about 140 nm.

In short, it is also possible to control the emission wavelength by arbitrarily combining the band gaps of the barrier layers sandwiching the light emitting layer, and by making the thickness of each layer and / or the Al: Ga composition ratio of each layer different. Further, the crystallinity of the light emitting layer can be enhanced by forming the barrier layer and the buffer layer with a plurality of layers and continuously changing the Al: Ga composition ratio.

As described in claim 2, by setting w = 0 and setting the composition of the light emitting layer to Ga ₂ O ₃ having two components, it is easy to control for uniformizing the crystal structure of the light emitting layer. Therefore, a high-quality deep ultraviolet light emitting element can be surely obtained. Further, in this case, since the band gap of the light emitting layer is 4.8-5.6 eV, a deep ultraviolet light emitting device having a light emitting wavelength of about 220-260 nm can be obtained.

According to the deep ultraviolet light emitting device according to claim 3, since the base material has a corundum structure common to gallium oxide crystals, the deep ultraviolet light emitting film formed on the base material has a high quality crystal structure. It is easy to say.

According to the method for manufacturing a deep ultraviolet light emitting device according to claim 4, it is possible to manufacture a deep ultraviolet light emitting device having a practical emission intensity by an atmospheric pressure process. Therefore, the deep ultraviolet light emitting element can be provided at low cost.

According to the method for manufacturing a deep ultraviolet light emitting element according to claim 5, the raw material mist is formed into Leiden frost in the reaction portion and flows so as to run on the surface of the base material, so that the uniformity is maintained on the surface of the base material. It is possible to form a high-quality deep-ultraviolet luminescent film.

According to the method for manufacturing a deep ultraviolet light emitting element according to claim 6, since a plurality of raw material supply containers are used, the supply amount can be controlled for each type of raw material, and the thickness of each layer and the Ga: Al ratio can be controlled. It is easy to adjust and design the film structure so as to obtain a deep ultraviolet light emitting element having a desired emission wavelength.

According to the method for manufacturing a deep ultraviolet light emitting device according to claim 7, the crystal structure of the light emitting layer is made uniform by setting w = 0 and setting the composition of the light emitting layer to Ga ₂ O ₃ having two components. Since the control for the conversion is facilitated, a high-quality deep-ultraviolet light emitting device can be reliably obtained. Further, in this case, since the band gap of the light emitting layer is 4.8-5.3 eV, a deep ultraviolet light emitting device having a light emitting wavelength of about 230-260 nm can be obtained.

According to the method for manufacturing a deep ultraviolet light emitting element according to claim 8, by introducing a support gas, the reactivity of the raw material mist is improved, which contributes to lowering the reaction temperature and reducing the amount of impurities mixed. Therefore, the manufacturing efficiency can be improved.

According to the method for manufacturing a deep ultraviolet light emitting device according to claim ₉ , the reactivity of the raw material mist can be further improved by using O3 gas as the supporting gas.

According to the method for manufacturing a deep ultraviolet light emitting element according to claim 10, since the base material cleaning step of cleaning the base material surface is further included, impurities can be removed from the base material surface on which the raw material mist is deposited, whereby impurities can be removed. The surface roughness of the deep ultraviolet light emitting film can be reduced, and the luminous efficiency can be further improved.

According to the method for manufacturing a deep ultraviolet light emitting element according to claim 11, the base material cleaning step includes an organic cleaning step of cleaning with an organic solvent or an organic acid and an ozone cleaning step of cleaning with _O3 gas. Cleaning of the material becomes more reliable.

It is a schematic diagram which shows an example of the thin film manufacturing apparatus for manufacturing the deep ultraviolet light emitting element which concerns on this invention. It is a schematic block diagram of the deep ultraviolet light emitting element which concerns on this invention. It is a graph which shows the X-ray diffraction measurement result of the deep ultraviolet light emitting element which concerns on this invention. It is a graph which shows the reciprocal lattice mapping measurement result of the deep ultraviolet light emitting element which concerns on this invention. The measurement result of the bandgap by the cathode luminescence measurement is shown, FIG. (A) is a graph showing the bandgap of the deep ultraviolet light emitting element according to the present invention, and FIG. be. It is a graph showing the X-ray diffraction measurement results of various thin films produced by changing the Ga: Al ratio, and the left column (1 Chamber) was produced using one raw material feeder (Al _x Ga _1-x ) ₂ . The O3 film _, the right column (2Chamber), is a (Al _x Ga _1-x ) ₂ O3 film produced using _two raw material feeders. It is a graph showing the change of the transmittance when the Ga: Al ratio of the thin film is changed, and the left column (1 Chamber) is generated by using one raw material feeder (Al _x Ga _1-x ) ₂ O ₃ The membrane, right column (2Chamber), is a (Al _x Ga _1-x ) ₂ O ₃ membrane produced using two raw material feeders. It is a graph showing each measured value of the band gap (■), the growth rate (●), and the locking curve half value (▲) of the thin film produced by changing the Ga: Al ratio, and the left column (1 Chamber) is. (Al _x Ga _1-x ) ₂ O ₃ film produced using one raw material feeder, right column (2 Chamber) produced using two raw material suppliers (Al _x Ga _1-x ) ₂ O ₃ It is a membrane.

[manufacturing device]
FIG. 1 is a schematic configuration diagram showing an example of a thin film manufacturing apparatus P used for manufacturing a deep ultraviolet light emitting device according to the present invention. In the thin film manufacturing apparatus P of this example, the first transport path R1 connecting the two raw material feeders 1A and 1B, the mixer 5, the film forming device 10, the two raw material feeders 1A and 1B, and the mixer 5 A second transport path R2 that connects the mixer 5 and the film forming apparatus 10 is included. This example does not require a vacuum device, and each component of the thin film manufacturing device P is not sealed, and therefore each step is performed under atmospheric pressure.

The two raw material feeders 1A and 1B are a mist generating means 2 for atomizing the raw material solutions L1 and L2 contained therein to generate the raw material mist M1 and M2, and a transport gas for transporting the raw material mist M1 and M2. It includes a transport gas introduction unit 3 into which G1 is introduced, and a mist delivery unit 4 in which the mist flows F1 and F2 in which the raw material mists M1 and M2 are contained in the transport gas G1 are delivered. In order to form a film having a desired composition ratio, one raw material is supplied by using a mixed solution of two kinds of raw materials instead of preparing two separate raw material feeders 1A and 1B as described above. It is also possible to form a film with a vessel. However, it is recommended to use two raw material feeders 1A and 1B because it facilitates the prediction and design of complex reactions and compositions.

As the mist generation means 2, in this example, a structure using an ultrasonic vibrator is used, but in addition, a spray-type mist-forming device or the like can also be used, and the mist generation means 2 is not particularly limited.

As the transport gas G1 for transporting the raw material mists M1 and M2, an inert gas having no activity for the film forming step, such as nitrogen N ₂ , helium He, argon Ar, neon Ne, and carbon dioxide CO ₂ , is suitable. Active gases such as oxygen O ₂ , chlorine Cl ₂ , hydrogen H ₂ , and carbon monoxide CO may be used, but it is not recommended to use them as carriers for safety reasons. Although air may be used, the use of nitrogen or the like is recommended from the viewpoint of contamination with impurities.

It is desirable that the introduction amount of the transfer gas G1 introduced into the raw material feeders 1A and 1B through the transfer gas introduction unit 3 is set or controlled to a predetermined value by, for example, a flow rate adjusting means such as a fan or a pump. .. Furthermore, it is also possible to control the introduction amount so as to change the flow rate of the conveyed gas during the film forming process.

In the mixer 5, the first transport path R1 is connected to the introduction side, the second transport path R2 is connected to the lead-out side, and the mist flow F1 internally transmitted from each of the two raw material feeders 1A and 1B. , F2 are mixed to generate a mixed mist flow F3. The mixing ratio of the two mist flows F1 and F2 is adjusted by using a flow meter or a flow controller, but the mixer 5 may be provided with a mechanism capable of adjusting the mixing ratio of the mist flows F1 and F2. When using a solution in which two or more kinds of raw materials are mixed, the mixer 5 can be omitted.

The film forming apparatus 10 includes a mist introduction unit 11 into which the raw material mist is introduced, an introduction chamber 10a communicating with the mist introduction unit 11, and a reaction unit 12 communicating with the introduction chamber 10a and arranging the base material S. A heating means 13 for heating the material S and a discharge unit 14 for discharging exhaust gas are provided.

The reaction unit 12 is a region for depositing raw material mists M1 and M2 on the base material S to form a film, and has a reaction flow path 12a inside thereof. The reaction flow path 12a is also a region where the base material S is arranged and the heating means 13 for heating the base material S is provided. In the reaction flow path 12a, the raw material mists M1 and M2 are placed on the base material S. Causes a thermochemical reaction to deposit.

The reaction unit 12 is characterized in that the height dimension of the reaction flow path 12a is set to be significantly lower than the height dimension of the introduction chamber 10a. That is, the reaction unit 12 is composed of two flat plates arranged in parallel with the upper and lower portions of the reaction flow path 12a provided with a slight gap of about 0.5-3.0 mm, for example 1.0-1.5 mm. It has a "fine channel structure". In this example, the height of the flow path of the reaction unit 12 is set to about 1.0 mm. The gap size can be set to about 1.5 mm, and this value can be appropriately changed according to the implementation conditions.

Further, it is desirable to provide a region on the upstream side of the heating means 13 in the reaction flow path 12a, that is, a region having a constant length from the introduction chamber 10a to the base material S. This region functions as a rectifying unit 15 for rectifying and preheating the fluid before guiding the mist flow to the substrate S.

It is considered that the reaction unit 12 functions as follows by having a fine channel structure. The raw material mists M1 and M2 supplied from the introduction unit 11 into the introduction chamber 10a are rectified by the rectifying unit 15 and then conveyed to the base material S. Since the height dimension of the reaction flow path 12a is set to be significantly smaller than that of the introduction chamber 10a, the flow velocity of the mist flow including the raw material mists M1 and M2 increases. In a multiphase flow of floating mist and gas, the gas flows at a higher speed than the mist. Further, the flow velocity distribution of the gas has a gradient from the inner surface of the flow path to the center. As a result, a rotational force is generated in the mist based on the velocity gradient of the gas, and a vertical downward force is generated. By such a mechanism, the force that presses the mist against the surface of the base material S acts on the mist, and as a result, it is presumed that the mist easily adheres to the surface of the base material S and the film formation is promoted.

Each mist delivery unit 4 of the two raw material feeders 1A and 1B and the mixer 5 are connected by a first transport path R1. The first transport path R1 is provided with a diluted gas introduction unit 6 for introducing the diluted gas G2 into the inside. The diluted gas G2 is mixed with the mist flows F1 and F2 sent from the raw material feeders 1A and 1B through the diluted gas introduction unit 6, and the mist concentration in the mist flows F1 and F2 is adjusted. This is also used for the purpose of avoiding condensation.

As the diluting gas G2, an inert gas having no activity for the film forming step, such as nitrogen N ₂ , helium He, argon Ar, neon Ne, and carbon dioxide CO ₂ , is used, and is preferably the same type as the transport gas G1. Use gas.

In addition, the flow rate of fans, pumps, etc. can be adjusted so that the amount of diluted gas G2 introduced can be adjusted in order to set the mist concentration to a predetermined value, to change it as appropriate, and to change it at the time of film formation. It is desirable to provide means.

The mixer 5 and the mist introduction portion 11 of the film forming apparatus 10 are connected by a second transport path R2. The second transport path R2 is provided with a support gas introduction unit 7 for introducing the support gas G3, if desired. The support gas G3 is for improving the reactivity of the raw material mists M1 and M2 to improve the film quality and the film formation efficiency, and ozone ₍ O3) is used in this example.

Ozone is easily radicalized to generate oxygen radicals (O.). In particular, when other molecules are present in the surroundings, they react easily and generate oxygen radicals. The radicalized substance causes a radical reaction with other substances, easily breaks the bond of the supplied raw material, and promotes the reaction. Therefore, by introducing ozone into the reaction system, the reactivity can be increased and the film quality can be improved. In addition, the reaction efficiency is also improved, and as a result, the temperature required for the reaction can be lowered, and the base material temperature can be lowered to save energy.

Further, in order to set the introduction amount of the support gas G3 to a predetermined value or to change it as appropriate, it is desirable to provide a flow rate adjusting means such as a fan or a pump capable of adjusting the introduction amount of the support gas G3. ..

In the illustrated example, the support gas introduction unit 7 is provided in the middle of the second transport path R2, but it is also possible to provide the support gas introduction unit 7 at an appropriate position facing the introduction chamber 10a of the film forming apparatus 10.

The support gas G3 used is not limited to ozone ₍ O3). Since plasma is generally used as a method for generating radicals, it is possible to use the radical source generated by introducing various gases into the plasma source. For example, it is also possible to use nitrogen radicals generated through nitrogen, hydrogen radicals generated through water vapor, and OH radicals. As the water vapor, one that promotes evaporation by using mist can be used. Further, although the type of radical cannot be specified such as O, N, and others, it is also possible to use a radical generated by using air.

[Film film material]
Next, a film forming material for a deep ultraviolet light emitting device manufactured by using the above-mentioned thin film manufacturing apparatus P will be described. The deep ultraviolet light emitting device, which is the object of this example, has a structure in which a gallium oxide-based oxide is deposited on the base material S, specifically, y of the barrier layer and z of the cap layer are set to x = y = z. The structure is such that (Al _x Ga _1-x ) ₂ O ₃ layers (however, 0 <x ≦ 1) and Ga ₂ O ₃ layers are alternately laminated.

The base material S may be any base material that crystallizes the gallium-based oxide, but here, it is particularly the same as the gallium-based oxides such as (Al _x Ga _1-x ) ₂ O ₃ and Ga ₂ O ₃ . A base material having a corundum structure and a sapphire base material are preferable. By using the sapphire base material, the crystallinity of the formed film can be enhanced. In addition to sapphire, any corundum structure having a similar corundum structure can be used. Furthermore, when forming Ga ₂ O ₃ having other crystal structures such as β, γ, and ε, it is conceivable to select a base material having an optimum structure according to the type of crystal structure. In this case, the emission wavelength may change with each structure.

A gallium (Ga) source and an aluminum (Al) source are housed in each of the two raw material feeders 1A and 1B. As the gallium source, for example, gallium acetylacetonate ₍ C15 H ₂₁ GaO ₆ : Ga (acac) ₃ ) solution L1 is used. Since acetylacetonate is sparingly soluble in ultrapure water, a solution was prepared by dissolving it in a solvent mixed with a small amount of hydrochloric acid. The reason for using ultrapure water is to avoid the influence of side reactions due to impurities as much as possible.

On the other hand, as the aluminum source, for example, aluminum acetylacetonate (C ₁₅ H ₂₁ AlO ₆ : Al (acac) ₃ ) solution L2 is used. Aluminum acetylacetonate was also prepared as a solution by dissolving it in a solvent mixed with a trace amount of hydrochloric acid in ultrapure water.

Further, when a chloride such as GaCl ₃ or AlCl ₃ is used as the solute, water, methanol, methyl acetate, a mixed solution thereof or the like can be used as the solvent. As described above, the type of the compound serving as the Ga source or the Al source and the type of the solute are not particularly limited. Of course, it is also possible to support acid (hydrochloric acid), alkali (NH ₃ ), etc. for solute dissolution or as a reaction support agent.

When the Ga ₂ O ₃ layer is formed on the base material S, only the mist flow F1 from the raw material supply device 1A accommodating the gallium source is guided to the film forming device 10. On the other hand, when the (Al _w Ga _1-w ) _2O3 layer is formed _on the base material S, the mist flow F1 from the raw material feeder 1A accommodating the gallium source and the raw material feeder 1B accommodating the aluminum source are used. The mist flow F2 of the above is mixed by the mixer 5, and the obtained mixed mist flow F3 is set to be guided to the film forming apparatus 10.

[Production method]
A method of manufacturing a deep ultraviolet light emitting device using the thin film manufacturing apparatus P described above will be described. In this example, first, a buffer layer composed of (Al _x Ga _1-x ) ₂ O ₃ (where 0 <x ≦ 1) is formed on the base material S, and light emission composed of Ga ₂ O ₃ is formed on the buffer layer. A layer is formed, a barrier layer composed of (Al _y Ga _1-y ) ₂ O ₃ is formed on the light emitting layer, a plurality of combinations of the light emitting layer and the barrier layer are provided, and finally, the uppermost light emitting layer is provided. It is an object of the present invention to obtain a deep ultraviolet light emitting element provided with a deep ultraviolet light emitting film having a structure in which a cap layer made of (Al _z Ga _1-z ) ₂ O ₃ is provided on the top.

₍ O3 cleaning process)
Prior to film formation, the base material S is placed on the reaction unit 12, and then only ozone gas is circulated. As a result, impurities such as carbon on the surface of the base material S can be oxidized and removed by CO ₂ or the like, so that the effect of cleaning the surface of the base material is brought about. In addition to the ozone cleaning step using O3 _, an organic cleaning step using an organic solvent or an organic acid can be adopted. Further, by further performing the ozone cleaning step after carrying out the organic cleaning step, it is possible to further ensure the cleaning of the base material.

(Formation of buffer layer)
First, a buffer layer composed of (Al _x Ga _{1-x ) 2O3} layers is formed on the substrate. This step includes the following steps:
First mist generation step: In one raw material supply device 1A, the Ga (acac) ₃ solution L1 is atomized by the mist generation means 2 to generate the first raw material mist M1.
Second mist generation step: In the other raw material supply device 1B, the Al (acac) ₃ solution L2 is atomized by the mist generation means 2 to generate the second raw material mist M2.
Mist mixing step: The transport gas G1 is supplied, and the first mist flow F1 containing the first raw material mist M1 and the second mist flow F2 containing the second raw material mist M2 are mixed through the first transport path R1. Transport to the vessel 5 and mix at an appropriate ratio. Diluting gas G2 is supplied to each of the first mist flow F1 and the second mist flow F2 to adjust the mist concentration appropriately.
Transfer step: The mixed mist flow F3 obtained by the mixer 5 is transferred to the film forming apparatus 10 through the second transfer path R2.
-Support gas mixing step: If desired, a support gas such as ozone gas is mixed with the mixed mist flow F3 in the middle of the transfer step.

The film forming step: The mixed mist flow F3 is introduced into the introduction chamber 10a of the film forming apparatus 10, passed through the reaction unit 12, and brought into contact with the heated base material S. The raw material mists M1 and M2 contained in the mixed mist flow F3 deposit an oxide on the base material S in a mixed crystal state of Ga and Al by a thermochemical reaction. As a result, a (Al _x Ga _1-x ) ₂ O ₃ layer is formed on the base material S. The residual mixed mist flow F3 that has passed through the reaction unit 12 is discharged to the outside from the discharge unit 14 as exhaust gas.

In this example, since the reaction unit 12 has a fine channel structure, the mixed mist flow F3 is rectified by the rectifying unit 15 and then introduced into the rapidly narrowed reaction flow path 12a. It is considered that the gas flows at a higher speed than the floating raw material mist particles, and the gas causes a velocity gradient from the inner surface of the flow path to the center. Therefore, a rotational force is generated in the raw material mist particles based on the velocity gradient of the gas, and a vertical downward force is generated. As a result, the raw material mist particles are pressed against the surface of the base material S, and it is considered that the effect of promoting the adhesion of the raw material mists M1 and M2 to the surface of the base material S can be obtained.

Further, in this example, the raw material mist M1. While M2 and the gas that conveys it are at room temperature, the base material S is heated to a high temperature. As a result, the atmosphere in the vicinity of the base material S becomes high, so that the surface of the raw material mist supplied to the reaction unit 12 is rapidly heated and vaporized, and a vapor phase portion composed of steam is formed on the surface of the droplet. It causes the Leidenfrost phenomenon to form. The Leidenfrost phenomenon is that when a droplet comes into contact with an atmosphere or solid that is sufficiently hotter than its boiling point, a vapor film with low thermal conductivity is instantly formed on the surface of the droplet, and this vapor film causes the droplet to surround the droplet. This is a phenomenon in which the evaporation time of droplets is dramatically increased by being insulated from the atmosphere or solid surface of the liquid. The Leidenfrosted raw material mist flows so as to run on the surface of the base material S, and a thermal decomposition reaction occurs in the gas phase portion covering the surfaces of the raw material mists M1 and M2 to form a thin film on the base material S. .. In this example, it is considered that by utilizing such a Leidenfrost phenomenon, it is possible to produce a high-quality thin film having high uniformity on the base material S.

Further, although the Leidenfrost phenomenon is not essential, it is preferable to cause it in order to improve the quality of the film. The temperature of the base material S for causing such a Leidenfrost phenomenon varies depending on the material, surface condition, solvent, etc. of the base material S, but when an aqueous solvent is used as in this example, it is set to at least 130 ° C. or higher. It is recommended to do. When methanol is used as the solvent I, lower temperatures are possible.

(Formation of light emitting layer)
Subsequently, a light emitting layer made of Ga ₂ O ₃ is formed on the buffer layer formed as described above. The step of forming the light emitting layer is almost the same as that of the step of forming the buffer layer, except that only the first raw material mist M1 obtained by atomizing the Ga (acac) ₃ solution L1 is used as the raw material mist. This step includes the following steps:
-Mist generation step: In one raw material supply device 1A, the Ga (acac) ₃ solution L1 is atomized by the mist generation means 2 to generate the first raw material mist M1.
Transfer step: The transfer gas G1 is supplied, and the first mist flow F1 including the first raw material mist M1 is transferred to the film forming apparatus 10 through the first transfer path R1 and the second transfer path R2. At that time, the diluted gas G2 is supplied to the first mist flow F1 to adjust the mist concentration to be appropriate.
-Support gas mixing step: If desired, a support gas such as ozone gas is mixed with the first mist flow F1 in the middle of the transfer step.
The film forming step: The first mist flow F1 is introduced into the introduction chamber 10a of the film forming apparatus 10, passed through the reaction unit 12, and brought into contact with the heated base material S. The raw material mist M1 contained in the first mist flow F1 is deposited on the base material S by a thermochemical reaction, whereby a Ga ₂ O ₃ layer is formed on the base material S. The residual first mist flow F1 that has passed through the reaction unit 12 is discharged to the outside from the discharge unit 14 as exhaust gas.

It is common with the formation of the buffer layer that the formation of the light emitting layer is promoted by the fine channel structure and that the uniformization and high quality of the light emitting layer are achieved by the Leidenfrost phenomenon.

(Formation of barrier layer and cap layer)
About the barrier layer consisting of (Al _y Ga _1-y ) ₂ O ₃ (where 0 <y ≦ 1) and the cap layer consisting of (Al _z Ga _1-z ) ₂ O ₃ (where 0 <z ≦ 1). In the example, the values of y and z are made common with the values of x in the buffer layer. Therefore, the barrier layer and the cap layer have the same composition as the buffer layer. Therefore, the steps of forming the barrier layer and the cap layer are the same as the steps of forming the buffer layer, except that the thickness of the layers to be formed is different. Therefore, the description of the manufacturing process here is omitted.

The (Al _x Ga _1-x ) ₂ O ₃ layer on the base material S can be an Al ₂ O ₃ layer (when x = 1), and (Al _w Ga _1-w ) ₂ O ₃ The layer can be a Ga ₂ O ₃ layer (when w = 1). Further, it is possible to add a dopant to each layer. As the type of dopant, an element having doping activity for Group 13 atoms such as tetravalent such as Si and Sn, pentavalent such as Sb, and monovalent and divalent such as Cu can be selected.

When adding a dopant, it is conceivable to further add a raw material supply device, mix three kinds of raw material solutions and four kinds of raw material solutions with a mixer, and supply them to the film forming device. When transporting multiple types of raw materials individually, it is recommended to use a mixer to mix them uniformly in order to make the reaction uniform. When a plurality of raw materials are mixed into one solution, if the required membrane compositions are multiple types, it becomes necessary to prepare a plurality of solutions having different charging amounts in order to prepare these films. On the other hand, according to the method of uniformizing with a mixer, solutions can be prepared for each type of raw material, and the supply amount of these can be controlled only by the flow velocity. It has the effect of being easily produced.

[Deep ultraviolet light emitting element]
FIG. 2 shows an example of the deep ultraviolet light emitting device Q manufactured by the above-mentioned manufacturing method. In this example, the composition of the buffer layer, the barrier layer, and the cap layer are the same. Therefore, in the following description, the composition of the barrier layer and the cap layer is the same as that of the buffer layer (Al _x Ga _1-x ) ₂ O ₃ It shall be displayed using.

In the deep ultraviolet light emitting element Q of this example, a layer made of (Al _x Ga _1-x ) ₂ O ₃ (where 0 <x ≦ 1) and a light emitting layer made of Ga ₂ O ₃ are formed on the base material S. Are alternately laminated and formed. Of the plurality of (Al _x Ga _1-x ) ₂ O ₃ layers, the lowest layer formed in contact with the base material S is the buffer layer, the uppermost layer is the cap layer, and the light emitting layer (Ga ₂ O ₃ layer). The layer arranged between) is the barrier layer.

The thickness of each of the buffer layer, the cap layer, and the barrier layer is set to be equal to or larger than the thickness of the light emitting layer, and the upper limit is about 1000 nm. The thickness of the light emitting layer is set to 0.1-10 nm.

The deep ultraviolet light emitting film Q of this example configured as described above is a multiple quantum well by alternately stacking a Ga ₂ O ₃ layer as a light emitting layer and a (Al _x Ga _1-x ) ₂ O ₃ layer. It forms a structure, thereby exhibiting practical emission intensity with a bandgap of 4.8-8.7 eV. Having a multiple quantum well structure can be confirmed, for example, by out-of-plane measurement by the X-ray diffraction (XRD) method or reciprocal lattice mapping measurement. The emission characteristics can be confirmed by cathode luminescence (CL) measurement.

The buffer layer is for alleviating the lattice mismatch between the base material S and the light emitting layer. By interposing an appropriate buffer layer between the substrate and the light emitting layer, it is possible to grow a heterolayer of desired quality even in the presence of lattice mismatch and differences in crystal structure, resulting in high quality. Contributes to the formation of crystal structure.

The deep ultraviolet light emitting device Q shown in FIG. 2 was manufactured according to the manufacturing conditions described below.
<Gallium-based film forming material>
Raw material solution Gallium acetylacetonate solution Solvent Pure water: Mixed solvent of hydrochloric acid (99.5: 0.5) Solute concentration 0.020 mol / L
<Aluminum-based film forming material>
Raw material solution Aluminum acetylacetonate solution Solvent Pure water: Mixed solvent of hydrochloric acid (99.5: 0.5) Solute concentration 0.040 mol / L
<Gas type>)
Transport gas Nitrogen gas Diluted gas Nitrogen gas <Gas flow rate>
・ Ga ₂ O ₃ layer forming transport gas: 5.0 L / min + dilution gas: 2.0 L / min ・ (Al _x Ga _1-x ) ₂ O ₃ layer forming (Ga side) transport gas: 2.0 L / Min + Diluted gas: 1.0 L / min (Al side) Transport gas: 3.0 L / min + Diluted gas: 1.0 L / min <Base material>
Material: C-plane sapphire base material Heating temperature: 400 ° C
<Mist generation means>
Ultrasonic oscillator: 2.4MHz, 24V, 0.625A, 3 pieces used <Deep ultraviolet light emitting film>
Light emitting layer (Ga ₂ O ₃ layer) 2 nm x 3
Buffer layer ((Al _x Ga _1-x ) ₂ O ₃ layer) 500 nm
Barrier layer ((Al _x Ga _1-x ) ₂ O ₃ layer) 10 nm x 2
Cap layer ((Al _x Ga _1-x ) ₂ O ₃ layer) 30 nm

<Evaluation>
The X-ray diffraction measurement result is shown in FIG. The vertical axis is the X-ray intensity and the horizontal axis is the angle of 2θ / ω. The sharp peak near 40.9 degrees is the c-axis orientation peak derived from the corundum-based structure of AlGaO. In addition, it can be inferred that there are overlapping peaks in the vicinity. The composition ratio calculated from X-ray diffraction or transmittance using Vegard's law was 30-46% for Al source and 70-54% for Ga source.

Next, FIG. 4 shows the results of the reciprocal lattice mapping measurement performed on the asymmetric surface of ( ^101-10 ). Interference fringes presumed to form a multiple quantum well structure could be confirmed in the c (qz) axis direction.

To measure the optical properties of the AlGaO layer only. When a single film of AlGaO prepared under the same conditions as this experiment was measured using a spectrophotometer, the transmittance of AlGaO was 80% or more in the visible light region, and the optical band gap calculated from it was about. It is 6.4 eV.

Furthermore, the emission characteristics were measured by cathode luminescence measurement. The results are shown in FIG. FIG. (A) is a measurement result of a deep ultraviolet light emitting element having a multiple quantum well structure (3MQW) according to the present invention, and FIG. (B) is a measurement result of only a sapphire substrate. The horizontal axis is energy and the vertical axis is CL intensity. The temperature dependence is measured, and the result of gradually increasing the temperature from 12K to room temperature (300K) is shown.

Cathodoluminescence (CL) measurement is a method for detecting the light emitted when a sample is irradiated with an electron beam. Crystal defects and impurities are detected by spectroscopically analyzing this light emission in the same manner as the photoluminescence method. , Carrier concentration, strain degree, etc. can be obtained. Since the CL measurement uses an electron beam, the electron beam can be operated using a capacitor and has a high degree of freedom. Therefore, by combining with SEM, for example, it is possible to compare images while observing the surface texture. In addition, since it irradiates a high-energy electron beam, it has the advantage that it can measure wavelengths that cannot be excited by vacuum ultraviolet light or current lasers, and it can also measure oxides with a wide bandgap.

The sharp peak near 1.8 eV of the sapphire substrate in FIG. 5B is a spike peak peculiar to the substrate. When the thin film on the sapphire substrate is thin, the electron beam reaches the substrate and the substrate emission is noticeable in the result. However, as shown in FIG. (A), no spike peak peculiar to the substrate is observed in the measurement result of this example. Therefore, it is considered that the light emission by the base material can be ignored. On the other hand, focusing on the light emission near about 4.9 eV, a peak is observed at a similar position in the sapphire base material, but the peak position is different between the deep ultraviolet light emitting film and the sapphire base material in this example. .. In addition, the temperature dependence is different. That is, in the sapphire base material, the change in CL strength is not monotonous with the increase in temperature, but an increasing tendency is observed. On the other hand, in this example, the CL intensity monotonously decreases as the temperature increases. This indicates that both have completely different light emitting processes, and it is proof that the light emission near about 4.9 eV in this example is not derived from the substrate. Therefore, it can be said that the CL measurement result in FIG. (A) represents the emission of only the thin film.

From the above description, based on the present invention, it is possible to manufacture a deep ultraviolet light emitting device having a multiple quantum well structure and exhibiting strong light emission in the deep ultraviolet region by an atmospheric pressure process. Therefore, it becomes possible to provide the ultraviolet light emitting element at a lower manufacturing cost than the conventional one.

Instead of the first embodiment, in one raw material supply device, a mixed solution containing a Ga source and an Al source is atomized to generate a mixed mist flow, which is supplied to the film forming device 10 to emit deep ultraviolet light. It is also possible to manufacture the element.

FIG. 6-8 shows a (Al _x Ga _{1-x ) 2O3} membrane prepared by a mixed mist stream generated from a mixed solution using one raw material feeder, and two raw material feeders 1A in the above embodiment. It shows the comparison of the physical properties with the (Al _x Ga _{1-x ) 2O3} membrane prepared by mixing the mist flows separately generated using 1B. The conditions for forming the film are the same as those in Example 1. FIG. 6 is a graph showing the results of X-ray diffraction measurement of various thin films in which the Ga: Al ratio is changed, and FIG. 7 is a graph showing the change in transmission rate when the Ga: Al ratio of the thin film is changed. Is a graph showing each measured value of the band gap (■), the growth rate (●), and the locking curve half value (▲) when the Ga: Al ratio of the thin film is changed. In each case, the measurement results of the (Al _x Ga _1-x ) _2O3 film prepared using one raw material feeder in the left column (1 Chamber), and the two raw material feeders in the right column ( ₂ Chamber). The measurement result of the prepared (Al _x Ga _{1-x ) 2O3} film is shown.

The Ga: Al ratio refers to the amount of these charged when a mixed solution of Al source and Ga source is contained in one container, and when the Al source and Ga source are separated in two containers, it means. Refers to the value converted from the flow rate ratio.

As can be seen from these graphs _, even a _2O3 film made using a single raw material feeder (Al _x Ga _1-x ) was made using two raw material feeders (Al _x Ga). _1-x ) Similar to the _2O3 film _, it can be seen that each physical property can be controlled by changing the Ga: Al ratio. Therefore, by setting an appropriate Ga: Al ratio, it is considered possible to manufacture a deep ultraviolet light emitting device having a light emission intensity equivalent to that in the case of manufacturing using two raw material feeders.

The deep ultraviolet light emitting element according to the present invention is considered to be applied as an ultraviolet light emitting element to an ultraviolet sensor, an ultraviolet laser, a sterilizing device, a reading / writing device for an information storage medium, and the like.

1A, 1B Raw material supply device 2 Mist generator 3 Transport gas introduction section 4 Mist delivery section 5 Mixer 6 Diluted gas introduction section 7 Support gas introduction section 10 Film forming device 11 Mist introduction section 12 Reaction section 13 Heating means 14 Discharge section 15 Rectifier F1 First mist flow F2 Second mist flow F3 Mixed mist flow G1 Transport gas G2 Diluted gas G3 Support gas M1 First raw material mist M2 Second raw material mist R1 First transport path R2 Second transport Path P Thin film manufacturing equipment Q Deep ultraviolet light emitting element

Claims (9)

A deep ultraviolet light emitting device provided with a base material and a deep ultraviolet light emitting film formed on the base material.
The deep ultraviolet light emitting film is
A buffer layer composed of (Al _x Ga _1-x ) ₂ O ₃ (where 0 <x ≦ 1) disposed on the substrate,
N (N is a natural number) light emitting layer composed of (Al _w Ga _1-w ) ₂ O ₃ (where 0 ≦ w <1) arranged on the buffer layer, and
An (N-1) barrier layer composed of (Al _y Ga _1-y ) ₂ O ₃ (where 0 <y ≦ 1) disposed between each of the N light emitting layers,
It includes a cap layer composed of (Al _z Ga _1-z ) ₂ O ₃ (provided that 0 <z ≦ 1) disposed on the uppermost light emitting layer.
The light emitting layer has a thickness of 0.1-10 nm and has a thickness of 0.1-10 nm.
The thickness of the buffer layer is 300-1000 nm.
The thickness of the barrier layer is set to be equal to or thicker than the layer thickness of the light emitting layer.
The thickness of the cap layer is set to be equal to or thicker than the layer thickness of the barrier layer.
The bandgap of the light emitting layer is 4.8-8.7 eV,
A deep ultraviolet light emitting element characterized by this. The deep ultraviolet light emitting device according to claim 1, wherein N is a natural number of 6 or less. The deep ultraviolet light emitting device according to claim 1 or 2, wherein the substrate has a corundum structure. It is a method of manufacturing a deep ultraviolet light emitting device by forming a deep ultraviolet light emitting film on a base material under atmospheric pressure using a thin film manufacturing apparatus.
The deep ultraviolet light emitting film is disposed on a buffer layer composed of (Al _x Ga _1-x ) ₂ O ₃ (where 0 <x ≦ 1) and a buffer layer (Al _w Ga _1-w ) ₂ . O ₃ (where 0 ≦ w <1) and N (where N is a natural number) light emitting layers are arranged between each of the N light emitting layers (Al _y Ga _1-y ) ₂ O ₃ (where N is a natural number). (N-1) barrier layers composed of 0 <y ≦ 1) and (Al _z Ga _1-z ) ₂ O ₃ (where 0 <z ≦ 1) are arranged on the uppermost light emitting layer. Including a cap layer consisting of
The thin film manufacturing apparatus is
It is provided with a mist generating means for atomizing the raw material solution to generate the raw material mist, a transport gas introducing unit into which the transport gas for transporting the raw material mist is introduced, and a mist sending section in which the raw material mist is delivered. More than one raw material feeder,
A mixer for mixing raw material mist sent from each of the plurality of raw material feeders,
A mist introduction part where the raw material mist is introduced, a reaction part where the region where the base material is placed is configured in a fine channel structure, a heating means for heating the base material, and an exhaust part for exhausting exhaust gas. A film forming device equipped with, and
A first transport path for connecting each mist delivery section of the plurality of raw material feeders to the mixer, and a first transport path having a diluted gas introduction section into which a diluted gas is introduced, and a mixer. A second transport path that connects to the mist introduction part of the film forming device,
It is a thin film manufacturing equipment including
The stage of forming a light emitting layer, a buffer layer, a barrier layer, or a cap layer on a substrate is
A first mist generation step of atomizing an Al-free raw material solution in which a Ga-containing raw material is dissolved to generate a first raw material mist in any one of the raw material feeders.
A second mist generation step of atomizing a Ga-free raw material solution in which an Al-containing raw material is dissolved to generate a second raw material mist in another raw material feeder.
A mist mixing step of transporting a first mist flow containing a first raw material mist and a second mist flow containing a second raw material mist to a mixer through a first transport path and mixing them.
A transfer step of transporting the mixed mist flow obtained by mixing the first mist flow and the second mist flow to the film forming apparatus through the second transport path, and
The mixed mist flow introduced into the film forming apparatus is brought into contact with the heated base material in the reaction section, and a raw material containing Ga and at least Al is deposited on the base material in a mixed crystal state by a thermochemical reaction. Including the process,
A method for manufacturing a deep ultraviolet light emitting device. The method for manufacturing a deep ultraviolet light emitting device according to claim 4, wherein the temperature of the base material is controlled so that the raw material mist causes a Leidenfrost phenomenon in the reaction portion in the film forming step. The transport path further includes a support gas introduction section into which a support gas for improving reactivity is introduced.
The method for manufacturing a deep ultraviolet light emitting device according to claim 4 or 5, wherein the transfer step further includes a support gas mixing step of mixing a support gas for improving the reactivity of the raw material mist. The method for manufacturing a deep ultraviolet light emitting device according to claim ₆ , wherein the support gas is O3 gas. The deep ultraviolet light emitting element according to any one of claims 4-7, further comprising a substrate cleaning step of cleaning the substrate surface with an organic solvent, an organic acid _, or an O3 gas prior to the film forming step. Manufacturing method. The method for manufacturing a deep ultraviolet light emitting element according to claim 8, wherein the substrate cleaning step includes an organic cleaning step of cleaning with an organic solvent or an organic acid and an ozone cleaning step of cleaning with _O3 gas.

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