阅读说明：本技术 一种氧化镓/氮化镓异质结光电探测器及其制备方法 (Gallium oxide/gallium nitride heterojunction photoelectric detector and preparation method thereof ) 是由 李炳生 韩玉蕊 王月飞 徐海阳 刘益春 于 2021-08-10 设计创作，主要内容包括：本发明涉及一种氧化镓/氮化镓异质结光电探测器及其制备方法,包括以下步骤：步骤1、氮化镓薄膜层的制备：步骤2、氮化镓薄膜从表面向下逐渐氧化形成不同厚度的氧化镓层；步骤3、氧化镓/氮化镓异质结器件的制备；本发明通过热氧化GaN的方法制备了β-Ga2O3/GaN异质结,该方法避免了外部杂质的引入引起的界面缺陷,其工艺简单,降低了器件的制备成本,制备的器件具有响应度高、暗电流小、稳定性好等特点。(The invention relates to a gallium oxide/gallium nitride heterojunction photoelectric detector and a preparation method thereof, wherein the preparation method comprises the following steps: step 1, preparing a gallium nitride thin film layer: step 2, the gallium nitride film is gradually oxidized from the surface downwards to form gallium oxide layers with different thicknesses; step 3, preparing a gallium oxide/gallium nitride heterojunction device; the beta-Ga 2O3/GaN heterojunction is prepared by the method for thermally oxidizing GaN, the method avoids interface defects caused by the introduction of external impurities, the process is simple, the preparation cost of the device is reduced, and the prepared device has the characteristics of high responsivity, small dark current, good stability and the like.)

1. A preparation method of a gallium oxide/gallium nitride heterojunction photoelectric detector comprises the following steps:

step 1, preparing a gallium nitride thin film layer:

(1) cleaning the substrate;

(2) preparing a gallium nitride film layer on the cleaned substrate by using film growth equipment;

step 2, the gallium nitride film is gradually oxidized from the surface downwards to form gallium oxide layers with different thicknesses;

(1) putting the gallium nitride film obtained in the step 1 into a high-temperature furnace capable of being communicated with atmosphere;

(2) setting the oxidation temperature, the oxidation time, the oxidation pressure and the gas flow in the oxidation process, carrying out thermal oxidation on the gallium nitride film to ensure that the gallium nitride film is partially oxidized into a gallium oxide layer, and taking out the sample after the oxidation is finished;

step 3, preparing a gallium oxide/gallium nitride heterojunction device;

(1) taking the sample subjected to thermal oxidation in the step 2, carrying out surface etching treatment on the sample, and partially removing the surface gallium oxide layer to expose the gallium nitride layer to obtain a required structural pattern;

(2) and respectively preparing ohmic contact electrodes on the exposed gallium oxide layer and the exposed gallium nitride film layer to obtain a heterojunction with a vertical structure, and completing the preparation of the photoelectric detector.

2. The method of claim 1, wherein the step of fabricating a gallium oxide/gallium nitride heterojunction photodetector comprises:

in the step 1, the substrate is a high temperature resistant substrate applicable to thin film growth, and comprises sapphire, silicon carbide, silicon, gallium oxide, aluminum nitride, gallium nitride or quartz glass.

3. The method of claim 1, wherein the step of fabricating a gallium oxide/gallium nitride heterojunction photodetector comprises:

in the step 1, the growth equipment is equipment applicable to film growth, and comprises molecular beam epitaxy, magnetron sputtering, pulsed laser deposition or metal organic chemical vapor deposition.

4. The method of claim 1, wherein the step of fabricating a gallium oxide/gallium nitride heterojunction photodetector comprises: in the step 2, the high-temperature furnace is a tube furnace, a box furnace or a high-pressure furnace which can be filled with oxygen.

5. The method of claim 1, wherein the step of fabricating a gallium oxide/gallium nitride heterojunction photodetector comprises: in the step 2, the gas introduced in the oxidation process is pure oxygen or a mixed gas of oxygen and inert gas.

6. The method of claim 1, wherein the step of fabricating a gallium oxide/gallium nitride heterojunction photodetector comprises: in the step 2, the oxidation temperature ranges from 500 ℃ to 1200 ℃; the oxidation time is 0-12 hours;the oxidation pressure intensity range is 1-10⁶Pa。

7. The method of claim 1, wherein the step of fabricating a gallium oxide/gallium nitride heterojunction photodetector comprises: in the step 2, if the gas flow is adjusted in the high temperature furnace, the oxygen flow is 1-500 sccm.

8. The method for preparing a gallium oxide/gallium nitride heterojunction photodetector as claimed in claims 1 to 7, wherein: in the step 3, the etching method is a method for removing the gallium oxide film by dry etching or wet etching.

9. The method for preparing a gallium oxide/gallium nitride heterojunction photodetector as claimed in claims 1 to 8, wherein: in step 3, the contact electrode is made of metal or other materials capable of forming ohmic contact with the thin film.

10. A gallium oxide/gallium nitride heterojunction photodetector, characterized by: prepared using the preparation process according to any one of claims 1 to 9.

Technical Field

The invention belongs to the field of semiconductor devices, and particularly relates to a gallium oxide/gallium nitride heterojunction photoelectric detector and a preparation method thereof.

Background

The solar spectrum contains a wide range of electromagnetic wavelengths, with ultraviolet radiation being a portion of the entire spectrum. The earth's atmosphere has a strong absorption of light with wavelengths below 200 nm, making it extremely difficult to propagate in the atmosphere. The ozone layer in the stratosphere strongly absorbs light with the wavelength of 200-280 nm, so that the light wave in the band in the solar spectrum can hardly reach the ground, and the solar spectrum is called as a solar blind band. Due to the fact that background noise of the solar blind ultraviolet signal in the atmosphere is low, the solar blind ultraviolet detection device generally has high signal-to-noise ratio and sensitivity. Detection of the solar blind spot is therefore of particular interest in the detection of red in ultraviolet light. The method can be widely applied to the military and civil fields of missile early warning, space secret communication, ozone monitoring, high-voltage power grid monitoring and the like.

Semiconductor materials commonly used for solar blind ultraviolet detection include AlGaN, MgZnO, diamond, Ga₂O₃And the like. The AlGaN and MgZnO are ternary alloy materials, have the advantages that the photoresponse wave band of the materials can be adjusted by changing the component proportion, and have the defect that the difficulty coefficient of the growth of high-quality materials is increased along with the improvement of Al (Mg) components in the alloys. With the improvement of Al component in AlGaN, the quality of the film is seriously degraded, and the detection performance of the device is greatly influenced. In MgZnO, the phase separation of the material occurs along with the improvement of the Mg component, so that the high-quality material is difficult to obtain. The response spectrum of diamond is below 225nm, making its detection in the solar-blind band inefficient. beta-Ga₂O₃As a wide-bandgap oxide semiconductor material, the bandgap width is 4.9eV, and the photoresponse peak is just positioned in the solar-blind band, so that the material is an ideal natural solar-blind ultraviolet detection material.

Common structures of the wide bandgap semiconductor photoelectric detector include a photoconductive type, a schottky type and a pn junction type. The difference of the device structure enables the device to have different characteristics in the aspect of photoelectric performance. The pn junction type device is a minority carrier device which is dominant in minority carrier transmission, and because the minority carrier concentration is lower, the change of photogenerated carriers to the minority carrier concentration is usually in magnitude, the pn junction type detector usually has higher detection sensitivity and higher signal-to-noise ratio. Intrinsic beta-Ga₂O₃The material is n-type conductive, the preparation of the p-type material is difficult,other p-type wide bandgap semiconductor materials are commonly utilized in combination with them to form heterojunction-type detectors for solar-blind ultraviolet detection. Wherein the gallium nitride (GaN) material is generally used for preparing beta-Ga due to mature growth technology₂O₃a/GaN heterojunction. The heterojunction is usually prepared by growing a GaN layer and then growing beta-Ga on the GaN layer₂O₃. In the growth of beta-Ga₂O₃Before, the GaN film usually contacts with air, and inevitably adheres to some impurities on the surface, so that defects are introduced to the interface of the heterojunction, and the preparation of a high-performance device is not facilitated. Thus, how to reduce heterojunction interface defects is in β -Ga₂O₃One of the problems to be solved in the fabrication of heterojunction devices.

Disclosure of Invention

The invention designs a gallium oxide/gallium nitride heterojunction photoelectric detector and a preparation method thereof, which solve the technical problem that beta-Ga grows in the prior art₂O₃Before, the GaN film usually contacts with air, and inevitably adheres to some impurities on the surface, so that defects are introduced to the interface of the heterojunction, and the preparation of a high-performance device is not facilitated.

In order to solve the technical problems, the invention adopts the following scheme:

a preparation method of a gallium oxide/gallium nitride heterojunction photoelectric detector comprises the following steps:

step 1, preparing a gallium nitride thin film layer: (1) cleaning the substrate; (2) preparing a gallium nitride film layer on the cleaned substrate by using film growth equipment;

and 2, gradually oxidizing the gallium nitride film from the surface to the inside to form gallium oxide layers with different thicknesses: (1) putting the gallium nitride film obtained in the step 1 into a high-temperature furnace capable of being communicated with atmosphere; (2) setting the oxidation temperature, the oxidation time, the oxidation pressure and the gas flow in the oxidation process, carrying out thermal oxidation on the gallium nitride film to ensure that the gallium nitride film is partially oxidized into a gallium oxide layer, and taking out the sample after the oxidation is finished;

step 3, preparing the gallium oxide/gallium nitride heterojunction device: (1) taking the sample subjected to thermal oxidation in the step 2, carrying out surface etching treatment on the sample, and partially removing the surface gallium oxide layer to expose the gallium nitride layer to obtain a required structural pattern; (2) and respectively preparing ohmic contact electrodes on the exposed gallium oxide layer and the exposed gallium nitride film layer to obtain a heterojunction with a vertical structure, and completing the preparation of the photoelectric detector.

Preferably, in step 1, the substrate is a high temperature resistant substrate applicable to thin film growth, and includes sapphire, silicon carbide, silicon, gallium oxide, aluminum nitride, gallium nitride, or quartz glass.

Preferably, in step 1, the growth equipment is equipment applicable to thin film growth, and includes molecular beam epitaxy, magnetron sputtering, pulsed laser deposition, or metal organic chemical vapor deposition.

Preferably, in the step 2, the high-temperature furnace is a tube furnace, a box furnace or a high-pressure furnace which can be filled with oxygen.

Preferably, in the step 2, the gas introduced in the oxidation process is pure oxygen or a mixed gas of oxygen and an inert gas.

Preferably, in the step 2, the oxidation temperature ranges from 500 ℃ to 1200 ℃; the oxidation time is 0-12 hours; the oxidation pressure intensity range is 1-10⁶Pa。

Preferably, in the step 2, if the gas flow is adjusted in the high temperature furnace, the oxygen flow is in a range of 1 to 500 sccm.

Preferably, in the step 3, the etching method is a method that can remove the gallium oxide film by dry etching or wet etching.

Preferably, in step 3, the contact electrode is made of metal or other materials capable of forming ohmic contact with the thin film.

A gallium oxide/gallium nitride heterojunction photoelectric detector prepared by the preparation method.

The gallium oxide/gallium nitride heterojunction photoelectric detector and the preparation method thereof have the following beneficial effects:

(1) the invention prepares beta-Ga by a method of thermally oxidizing GaN₂O₃A GaN heterojunction, which avoids interface defects caused by the introduction of external impurities and has simple processThe preparation cost of the device is reduced, and the prepared device has the characteristics of high responsivity, small dark current, good stability and the like.

(2) In step 2, because the heterojunction is usually grown by first growing a first gallium nitride layer and then growing a second gallium oxide layer, before the second layer is grown, the grown film of the first layer is usually taken out of the growing equipment and placed into the growing equipment of the film of the second layer, air is contacted in the transfer process, dust or gas molecules in the air are adsorbed on the surface of the film of the first layer, and then the adsorbed substances are remained on the interface of the two films in the second growing process to influence the quality of the interface. The method omits the second growth, directly oxidizes the first layer and gradually oxidizes the first layer from outside to inside, and the whole process can avoid the introduction of impurities.

(3) The method has the other advantage that the interface performance is better, and the interface has a large number of defects when the gallium oxide/gallium nitride heterojunction is realized by an epitaxial method under the general condition. The crystal phases of the two materials are different, one material is in a hexagonal structure, the other material is in a monoclinic system, and a large number of dangling bonds are arranged at the interface. In the method of the present invention, the surface gallium nitride is converted into gallium oxide by thermal oxidation, so that interface dangling bonds are reduced.

Drawings

FIG. 1 shows beta-Ga of the present invention₂O₃Sectional scanning electron microscope images of/GaN heterojunction.

FIG. 2 shows beta-Ga of the present invention₂O₃XRD pattern of/GaN heterojunction.

FIG. 3 shows beta-Ga of the present invention₂O₃IV plots of dark state and light illumination for/GaN heterojunction devices.

FIG. 4 shows beta-Ga of the present invention₂O₃Photoresponse spectrum of/GaN heterojunction device.

Detailed Description

The invention is further illustrated below with reference to fig. 1 to 3:

the present invention will be further described with reference to specific examples in order to better understand the present invention.

Example 1:

step 1: and (5) preparing the GaN film. Firstly, cleaning a substrate, taking a single-polished c-plane sapphire substrate with the diameter of 2 inches, carrying out ultrasonic cleaning on the substrate for 10 minutes by sequentially using acetone, alcohol and deionized water, taking out nitrogen, drying the nitrogen, putting the nitrogen into a growth cavity, and carrying out epitaxial growth on a GaN film by using a metal organic chemical vapor deposition method, wherein the film is in a hexagonal wurtzite structure, is (002) -oriented and has the thickness of about 4 microns.

Step 2: and (4) oxidizing the GaN thin film. Firstly, placing the GaN film prepared in the first step into a constant temperature area of a tubular furnace, setting the thermal oxidation temperature to be 900 ℃, the oxidation time to be 3h, the heating rate to be 5 ℃/min, the argon flow to be 100 sccm, the oxygen flow to be 30 sccm and the oxidation pressure to be 1 multiplied by 10⁵Pa, obtaining a sample after thermal oxidation.

And step 3: and (5) preparing a device. Firstly, putting the obtained sample part into concentrated phosphoric acid solution at 100 ℃, standing for 1 min, taking out, washing with deionized water to finish the treatment of beta-Ga₂O₃And exposing the lower GaN film. Then using thermal evaporation method to remove beta-Ga₂O₃And respectively evaporating metal Al on the GaN to be used as ohmic electrodes, thus finishing the preparation of the device.

FIG. 1 is a cross-sectional SEM image of a device with distinct boundaries for different materials, which are sequentially beta-Ga 2O3, GaN and sapphire substrates from top to bottom.

FIG. 2 is a view of beta-Ga₂O₃XRD pattern of/GaN heterostructure, where beta-Ga is seen₂O₃Diffraction peaks of GaN and sapphire substrates, in which beta-Ga is marked₂O₃Is (-201) orientation, and both the GaN and sapphire substrates are (002) orientation. Shows that beta-Ga is successfully prepared by a thermal oxidation method₂O₃A film.

FIG. 3 is a view of beta-Ga₂O₃The IV diagram of the/GaN heterostructure shows that the current of the device is obviously changed after the device is irradiated by ultraviolet light, and the photoresponse characteristic is good.

Fig. 4 is a spectral response of the device in the ultraviolet band. It can be seen that the device has response peaks at 250 nm and 370 nm, and the device exhibits dual-band detection characteristics, and the response values of the device in the solar-blind band and the visible busy band are respectively 15mA/W and 7 mA/W.

Example 2:

this example is the same as example 1 except for the following features: in this embodiment, the thermal oxidation temperature is 1000 deg.C, the thermal oxidation time is 1 h, the oxygen flow rate is 20 sccm, and the thermal oxidation pressure is 1 × 10³Pa。

Example 3:

this example is the same as example 1 except for the following features: in this embodiment, a pulsed laser deposition method is used to prepare a GaN thin film, wherein the thermal oxidation temperature is 800 ℃, the thermal oxidation time is 3 hours, and the oxygen flow rate is 50 sccm.

The invention is described above with reference to the accompanying drawings, it is obvious that the implementation of the invention is not limited in the above manner, and it is within the scope of the invention to adopt various modifications of the inventive method concept and solution, or to apply the inventive concept and solution directly to other applications without modification.