A method for preparing a negative photoconductive solar-blind detector using β-phase gallium oxide crystal

Abstract

The present invention relates to a method for preparing a negative photoconductive solar-blind detector using a β-phase gallium oxide crystal, comprising: (1) preparing an n-type doped gallium oxide substrate: mechanically exfoliating the n-type doped Ga 2 O 3 Crystal, obtain an atomically flat and clean surface to obtain a gallium oxide wafer; (2) prepare a negative photoconductivity solar blind detector by successively cleaning the gallium oxide wafer obtained in step (1), defining the electrode pattern by photolithography, and growing the electrode; the present invention is the first to observe the negative photoconductivity phenomenon in the ultraviolet band in a gallium oxide photodetector. The device has excellent negative photoconductivity performance. Under the irradiation of 254nm light, the device shows a high negative response, with a responsivity of 14.6A / W, a fast response speed, and a stable and reversible response to periodic on / off optical switching. The negative photoconductivity characteristics of gallium oxide crystals provide new possibilities for their application in optoelectronic devices.

Description

Technical Field

[0001] The invention relates to a method for preparing a negative photoconductive solar-blind detector by utilizing beta-phase gallium oxide crystal, and belongs to the technical field of semiconductors. Background Art

[0002] The photoconductivity effect refers to the change in the conductivity of a semiconductor after being exposed to light. The photoconductivity effect has important application value in the fields of biomedical monitoring, environmental detection, information transmission and processing, space exploration, wearable electronics, etc. At present, the research on the photoconductivity effect focuses on the positive photoconductivity effect, and there is very little research on the negative photoconductivity effect. In addition to the application prospects of negative photoconductivity in the fields mentioned above, negative photoconductivity devices can also be combined with positive photoconductivity devices to form photoelectric logic gates to achieve full-function logic operation and control. Existing reports show that negative photoconductivity can only be observed in a few material systems, with few research opportunities, weak theoretical basis, and controversial physical mechanisms. At present, the negative photoconductivity effect has been observed in a few low-dimensional material systems (such as nanoparticles, nanowires, and thin films) such as Co-doped Si, InAs, GeS, ZnSe, Black Phosphorus, and FePS3. There are three main explanations for the mechanism of negative photoconductivity in the literature: (1) trap effect. There are a large number of traps in the surface layer. The concentration of surface trap states is greater than the equilibrium carrier concentration. After illumination, these traps capture photogenerated electrons, while photogenerated holes capture free electron carriers, thereby producing negative photoconductivity. (2) adsorption / desorption of surface molecules. After illumination, the desorption of surface adsorbents (such as water molecules) leads to a decrease in the electron doping concentration of certain materials. (3) The interaction between surface plasmons and electrons. The incident light wave and the surface electrons generate new scattering channels due to resonance, which increases the material resistance and produces negative photoconductivity.

[0003] Gallium oxide has attracted much attention in the field of ultraviolet photodetection due to its ultra-wide band gap (~4.9eV), absorption cutoff edge (~254nm) just in the solar-blind band, increasingly mature single crystal growth process, low process cost (such as guided mode method), good chemical stability of materials, and radiation resistance. Since 2013, gallium oxide photodetection devices have developed rapidly, but they are mainly aimed at positive photoconductivity effect. The study of negative photoconductivity effect of gallium oxide is not only a supplement to the basic theory of gallium oxide-based photodetection devices, but also lays the foundation for combining positive and negative photoconductivity effects in gallium oxide materials to design and realize photoelectric logic circuits. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for preparing a negative photoconductive solar-blind detector using β-phase gallium oxide crystal;

[0005] Gallium oxide is a photoelectric material that has attracted much attention in recent years, but the photodetectors based on gallium oxide materials are all aimed at the positive photoconductivity effect. This invention discovered for the first time the negative photoconductivity effect of gallium oxide photodetectors in the solar-blind band, which is of great significance for studying the photoresponse characteristics of gallium oxide materials and exploring the formation mechanism of negative photoconductivity. In addition, the negative photoconductivity characteristics of gallium oxide provide new possibilities for its application in photoelectric devices.

[0006] Terminology explanation:

[0007] 1. Room temperature, also known as normal temperature or general temperature, is generally defined as 25 degrees Celsius. Sometimes it is set to 300K (about 27°C) to facilitate calculations using absolute temperature.

[0008] 2. Interdigitated electrodes are electrodes with periodic patterns in the surface, such as fingers or combs. This type of electrode is conducive to achieving a larger channel width and increasing the device current.

[0009] The technical solution of the present invention is:

[0010] A method for preparing a negative photoconductive solar-blind detector using a β-phase gallium oxide crystal comprises the following steps:

[0011] (1) Preparation of n-type doped gallium oxide substrate: Obtaining an atomically flat and clean surface by mechanically exfoliating n-type doped Ga2O3 crystals to obtain a gallium oxide wafer;

[0012] (2) preparing a negative photoconductive solar-blind detector by successively cleaning the gallium oxide wafer obtained in step (1), defining the electrode pattern by photolithography, and growing the electrode;

[0013] The photolithography-defined electrode pattern refers to: using the photolithography process to prepare the electrode pattern on the obtained gallium oxide wafer.

[0014] According to the preferred embodiment of the present invention, the electron doping concentration of the gallium oxide wafer is 1×10 18 -5×10 19 cm -3 ;

[0015] Further preferably, the electron doping concentration of the gallium oxide wafer is 1×10 18 cm -3 .

[0016] According to the preferred embodiment of the present invention, the gallium oxide wafer has a length of 2-4 cm, a width of 1-2 cm, and a thickness of 10-150 μm; the material of the n-type doped gallium oxide substrate is Si-doped gallium oxide;

[0017] More preferably, the gallium oxide wafer has a length of 4 cm, a width of 2 mm, and a thickness of 100 μm.

[0018] Preferably, according to the present invention, an interdigital electrode pattern is prepared on the obtained gallium oxide wafer.

[0019] Preferably, according to the present invention, in step (1), a mechanical peeling method is used to peel and obtain the gallium oxide wafer.

[0020] Preferably, according to the present invention, the gallium oxide wafer obtained in the cleaning step (1) refers to: using a Decon cleaning agent to perform ultrasonic cleaning at a power of 40-100 W for 3-10 min, using deionized water to perform ultrasonic cleaning at a power of 40-100 W for 3-10 min, using acetone to perform ultrasonic cleaning at a power of 40-100 W for 3-10 min, using ethanol to perform ultrasonic cleaning at a power of 40-100 W for 3-10 min, and then drying with nitrogen for use.

[0021] Most preferably, the gallium oxide wafer obtained in the cleaning step (1) is cleaned by: using a Decon cleaning agent with a power of 40 W for 5 minutes, using deionized water with a power of 40 W for 10 minutes, using acetone with a power of 40 W for 5 minutes, using ethanol with a power of 40 W for 5 minutes, and then drying with nitrogen for later use.

[0022] According to the preferred embodiment of the present invention, the electrode is grown by magnetron sputtering, wherein the gas atmosphere during the deposition process on the contact surface with the gallium oxide wafer is an argon-oxygen mixed gas, which is conducive to the formation of Pd oxide, thereby improving the work function of Pd, and the gas atmosphere during the deposition on the non-contact surface is pure argon gas, which is conducive to the formation of Pd metal. The electrode obtained is a double-layer structure of palladium / palladium oxide, i.e., Pd / PdO X Double layer structure, Pd / PdO X The double-layer structure includes PdO X , Pd, the value range of X is 0-1;

[0023] Deposition of PdO on GaO wafers X The process parameters in magnetron sputtering are as follows:

[0024] The target material is Pd metal target;

[0025] Sputtering power is 30-100W;

[0026] Working pressure is 3.45-4.00mTorr;

[0027] The gas flow rate is 13-20 SCCM;

[0028] The substrate temperature is room temperature;

[0029] The growth atmosphere is an argon-oxygen mixture with an O2 content of 2.5%-35%;

[0030] Sputtering time is 60-900s;

[0031] In PdO X When depositing Pd on the surface, the process parameters in magnetron sputtering are as follows:

[0032] The target material is Pd metal target;

[0033] Sputtering power is 30-100W;

[0034] The working pressure is 3.55-4.10mTorr;

[0035] The gas flow rate is 13-20 SCCM;

[0036] The substrate temperature is room temperature;

[0037] The growth atmosphere was pure argon environment;

[0038] The sputtering time is 300-900s.

[0039] More preferably,

[0040] Deposition of PdO on GaO wafers X The process parameters in magnetron sputtering are as follows:

[0041] The sputtering power is 40W;

[0042] The working pressure is 3.46mTorr;

[0043] The gas flow rate was 20 SCCM;

[0044] The growth atmosphere is an argon-oxygen mixture with 25% O2 content;

[0045] The sputtering time was 630 s.

[0046] In PdO X When depositing Pd on the surface, the process parameters in magnetron sputtering are as follows:

[0047] The sputtering power is 40W;

[0048] The working pressure is 3.67mTorr;

[0049] The gas flow rate was 20 SCCM;

[0050] The growth atmosphere was pure argon;

[0051] The sputtering time was 600 s.

[0052] The PdOx film deposited by magnetron sputtering is doped with a certain amount of oxygen during the deposition process, which helps to improve the quality of the Schottky contact and increase the Schottky barrier height.

[0053] The beneficial effects of the present invention are:

[0054] The present invention prepares an interdigital photodetector device by depositing PdOx / Pd Schottky electrodes on a Si-doped gallium oxide wafer, and observes negative photoconductivity in the ultraviolet band for the first time in a gallium oxide photodetector device. The device has excellent negative photoconductivity performance. Under the irradiation of 254nm light, the device exhibits a high negative response, with a responsivity of 14.6A / W, a fast response speed, and a stable and reversible response to periodic on / off optical switching. The discovery of negative photoconductivity of gallium oxide is of great significance for deepening the understanding of the photoresponse mechanism of gallium oxide materials. It provides new possibilities for its application in optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic diagram of an optical image of an interdigital electrode prepared in the present invention;

[0056] Figure 2 This is a schematic diagram of the structure of a negative photoconductive solar-blind detector;

[0057] Figure 3 Schematic diagram of the performance of a negative photoconductive solar-blind detector. DETAILED DESCRIPTION

[0058] The present invention will be further defined below in conjunction with the accompanying drawings and embodiments, but is not limited thereto.

[0059] Example 1

[0060] A method for preparing a negative photoconductive solar-blind detector using a β-phase gallium oxide crystal comprises the following steps:

[0061] (1) Preparation of n-type doped gallium oxide substrate: The n-type doped Ga2O3 crystal is mechanically peeled off to obtain an atomically flat and clean surface. The gallium oxide wafer is obtained by mechanical peeling. The electron doping concentration of the gallium oxide wafer is 1×10 18 -5×10 19 cm -3 ; The length of the gallium oxide wafer is 2-4 cm, the width is 1-2 cm, and the thickness is 10-150 μm; the material of the n-type doped gallium oxide substrate is Si-doped gallium oxide;

[0062] (2) preparing a negative photoconductive solar-blind detector by successively cleaning the gallium oxide wafer obtained in step (1), defining the electrode pattern by photolithography, and growing the electrode;

[0063] The photolithography-defined electrode pattern refers to: using the photolithography process to prepare the electrode pattern on the obtained gallium oxide wafer.

[0064] The gallium oxide wafer obtained in the cleaning step (1) refers to: using a Decon cleaning agent to perform ultrasonic cleaning at a power of 40-100 W for 3-10 min, using deionized water to perform ultrasonic cleaning at a power of 40-100 W for 3-10 min, using acetone to perform ultrasonic cleaning at a power of 40-100 W for 3-10 min, using ethanol to perform ultrasonic cleaning at a power of 40-100 W for 3-10 min, and then drying with nitrogen for later use.

[0065] The growth electrode refers to: using the magnetron sputtering method, the gas atmosphere during the deposition process on the contact surface with the gallium oxide wafer is an argon-oxygen mixed gas, which is conducive to the formation of Pd oxide, thereby improving the work function of Pd, and the gas atmosphere during the deposition on the non-contact surface is pure argon gas, which is conducive to the formation of Pd metal. The electrode obtained is a double-layer structure of palladium / palladium oxide, namely Pd / PdO X Double layer structure, Pd / PdO X The double-layer structure includes PdO X , Pd, the value range of X is 0-1;

[0066] Deposition of PdO on GaO wafers X The process parameters in magnetron sputtering are as follows:

[0067] The target material is Pd metal target;

[0068] Sputtering power is 30-100W;

[0069] Working pressure is 3.45-4.00mTorr;

[0070] The gas flow rate is 13-20 SCCM;

[0071] The substrate temperature is room temperature;

[0072] The growth atmosphere is an argon-oxygen mixture with an O2 content of 2.5%-35%;

[0073] Sputtering time is 60-900s;

[0074] In PdO X When depositing Pd on the surface, the process parameters in magnetron sputtering are as follows:

[0075] The target material is Pd metal target;

[0076] Sputtering power is 30-100W;

[0077] The working pressure is 3.55-4.10mTorr;

[0078] The gas flow rate is 13-20 SCCM;

[0079] The substrate temperature is room temperature;

[0080] The growth atmosphere was pure argon environment;

[0081] The sputtering time is 300-900s.

[0082] Example 2

[0083] The method for preparing a negative photoconductive solar-blind detector using a β-phase gallium oxide crystal according to Example 1 is different in that:

[0084] The electron doping concentration of the gallium oxide wafer is 1×10 18 cm -3 The gallium oxide wafer has a length of 4 cm, a width of 2 mm, and a thickness of 100 μm. An interdigital electrode pattern is prepared on the obtained gallium oxide wafer.

[0085] The gallium oxide wafer obtained in the cleaning step (1) is: ultrasonically cleaned with a Dicon cleaning agent at a power of 40 W for 5 minutes, ultrasonically cleaned with deionized water at a power of 40 W for 10 minutes, ultrasonically cleaned with acetone at a power of 40 W for 5 minutes, and ultrasonically cleaned with ethanol at a power of 40 W for 5 minutes, and then dried with nitrogen for use.

[0086] Deposition of PdO on GaO wafers X The process parameters in magnetron sputtering are as follows:

[0087] The sputtering power is 40W;

[0088] The working pressure is 3.46mTorr;

[0089] The gas flow rate was 20 SCCM;

[0090] The growth atmosphere is an argon-oxygen mixture with 25% O2 content;

[0091] The sputtering time was 630 s.

[0092] In PdO X When depositing Pd on the surface, the process parameters in magnetron sputtering are as follows:

[0093] The sputtering power is 40W;

[0094] The working pressure is 3.67mTorr;

[0095] The gas flow rate was 20 SCCM;

[0096] The growth atmosphere was pure argon;

[0097] The sputtering time was 600 s.

[0098] The PdOx film deposited by magnetron sputtering is doped with a certain amount of oxygen during the deposition process, which helps to improve the quality of the Schottky contact and increase the Schottky barrier height.

[0099] The photoelectric performance of the device of the gallium oxide wafer was tested, analyzed and characterized; the chemical state of the gallium oxide wafer was analyzed and characterized by X-ray photoelectron spectroscopy (XPS); in order to verify the reason for the occurrence of negative photoconductivity on the gallium oxide wafer, the surface energy band and surface morphology of the gallium oxide were characterized by scanning tunneling microscopy (STM). The photoelectric performance of the gallium oxide photodetector was tested using an Agilent B2900 semiconductor analyzer and a xenon lamp light source.

[0100] The optical image of the prepared interdigital electrode is shown in Figure 1 As shown; an interdigital photodetector is prepared on a gallium oxide wafer;

[0101] The structure of the negative photoconductive solar-blind detector prepared is as follows Figure 2 As shown; Figure 2 The main structural distribution of gallium oxide photodetectors is shown, indicating that the preparation process is simple;

[0102] Figure 3 Schematic diagram of the performance of negative photoconductivity day-blind detector; wherein, (a) is the IV curve under dark and light conditions, the ordinate is the current of the interdigital device under light and dark conditions, and the abscissa is the voltage applied to both ends of the interdigital electrodes. It can be clearly seen that under light conditions, the device current decreases, showing a negative photoconductivity effect; (b) is the time domain photocurrent switching characteristic; the ordinate is the current of the interdigital device under changes in light and dark conditions, and the abscissa is time, reflecting that the negative photoconductivity of gallium oxide has a fast response speed, and the response to the periodic on / off optical switch is stable and reversible.

Claims

1. A method for preparing a negative photoconductive solar-blind detector using β-phase gallium oxide crystal, characterized in that: The steps include: (1) Preparation of n-type doped gallium oxide substrate: peel off the n-type doped Ga2O3 crystal to obtain an atomically flat and clean surface to obtain a gallium oxide wafer; (2) preparing a negative photoconductive solar-blind detector by successively cleaning the gallium oxide wafer obtained in step (1), defining the electrode pattern by photolithography, and growing the electrode; The photolithographically defined electrode pattern refers to: using a photolithographic process to prepare an electrode pattern on the obtained gallium oxide wafer; the electrode pattern is an interdigitated electrode pattern; The growth electrode refers to: the gas atmosphere during the deposition process on the contact surface with the gallium oxide wafer is an argon-oxygen mixed gas, and the gas atmosphere on the non-contact surface is pure argon gas. The electrode obtained is a double-layer structure of palladium / palladium oxide, that is, Pd / PdO X Double layer structure, Pd / PdO X The double-layer structure includes PdO X , Pd, the value range of X is 0-1; Deposition of PdO on GaO wafers X The process parameters in magnetron sputtering are as follows: The target material is Pd metal target; Sputtering power is 30-100 W; The working pressure is 3.45-4.00 mTorr; Gas flow rate is 13-20 SCCM; The substrate temperature is room temperature; The growth atmosphere is an argon-oxygen mixture with an O2 content of 2.5%-35%; Sputtering time is 60-900s; In PdO X When depositing Pd on the surface, the process parameters in magnetron sputtering are as follows: The target material is Pd metal target; Sputtering power is 30-100 W; The working pressure is 3.55-4.10 mTorr; Gas flow rate is 13-20 SCCM; The substrate temperature is room temperature; The growth atmosphere was pure argon environment; The sputtering time is 300-900s.

2. The method for preparing a negative photoconductive solar-blind detector using β-phase gallium oxide crystal according to claim 1, characterized in that: The electron doping concentration of the gallium oxide wafer is 1×10 18 -5×10 19 cm -3 .

3. The method for preparing a negative photoconductive solar-blind detector using β-phase gallium oxide crystal according to claim 1, characterized in that: The electron doping concentration of the gallium oxide wafer is 1×10 18 cm -3 .

4. The method for preparing a negative photoconductive solar-blind detector using β-phase gallium oxide crystal according to claim 1, characterized in that: The length of the gallium oxide wafer is 2-4 cm, the width is 1-2 cm, and the thickness is 10-150 µm; the material of the n-type doped gallium oxide substrate is Si-doped gallium oxide.

5. The method for preparing a negative photoconductive solar-blind detector using β-phase gallium oxide crystal according to claim 4, characterized in that: The gallium oxide wafer has a length of 4 cm, a width of 2 mm and a thickness of 100 µm.

6. The method for preparing a negative photoconductive solar-blind detector using β-phase gallium oxide crystal according to claim 1, characterized in that: In step (1), a mechanical peeling method is used to peel and obtain a gallium oxide wafer.

7. The method for preparing a negative photoconductive solar-blind detector using β-phase gallium oxide crystal according to claim 1, characterized in that: The gallium oxide wafer obtained in the cleaning step (1) is: ultrasonically cleaned for 3-10 min using a Dicon cleaning agent at a power of 40-100 W, ultrasonically cleaned for 3-10 min using deionized water at a power of 40-100 W, ultrasonically cleaned for 3-10 min using acetone at a power of 40-100 W, and ultrasonically cleaned for 3-10 min using ethanol at a power of 40-100 W, and then dried with nitrogen for later use.

8. The method for preparing a negative photoconductive solar-blind detector using β-phase gallium oxide crystal according to claim 1, characterized in that: The gallium oxide wafer obtained in the cleaning step (1) is: ultrasonically cleaned with a Dicon cleaning agent at a power of 40 W for 5 minutes, ultrasonically cleaned with deionized water at a power of 40 W for 10 minutes, ultrasonically cleaned with acetone at a power of 40 W for 5 minutes, and ultrasonically cleaned with ethanol at a power of 40 W for 5 minutes, and then dried with nitrogen for later use.

9. The method for preparing a negative photoconductive solar-blind detector using β-phase gallium oxide crystal according to claim 8, characterized in that: Deposition of PdO on GaO wafers X The process parameters in magnetron sputtering are as follows: The sputtering power is 40 W; The operating pressure is 3.46 mTorr; The gas flow rate was 20 SCCM; The growth atmosphere is an argon-oxygen mixture with 25% O2 content; The sputtering time was 630 s; In PdO X When depositing Pd on the surface, the process parameters in magnetron sputtering are as follows: The sputtering power is 40 W; The operating pressure is 3.67 mTorr; The gas flow rate was 20 SCCM; The growth atmosphere was pure argon; The sputtering time was 600 s.

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