SnO / beta-Ga2O3 power diode and preparation method thereof

Abstract

The invention discloses a SnO / beta-Ga2O3 power diode and a preparation method of the SnO / beta-Ga2O3 power diode, and a p-type SnO layer is deposited on a beta-Ga2O3 epitaxial layer to construct a SnO / beta-Ga2O3 vertical structure heterojunction diode or a heterojunction barrier diode. The reverse leakage current of the power diode is reduced and the reliability and the breakdown voltage of the device are improved by utilizing the depletion region of the II-type heterojunction, and meanwhile, the heterojunction has lower built-in potential, is expected to reduce the conduction power consumption and can be used for a high-voltage and high-power power electronic system.

Description

Technical Field

[0001] The present invention belongs to the technical field of power devices and particularly relates to a SnO / β -Ga2O3 power diode and its preparation method. Background Art

[0002] With the rapid development of power electronics technology, the demand for power semiconductor devices in various applications is growing. Especially in high-voltage and high-current applications such as electric vehicles, renewable energy systems, industrial control and other fields, high-efficiency and low-loss power diodes have become one of the key components. Although traditional silicon-based power diodes have been widely used and have met these needs to a certain extent, their inherent physical limitations, such as low breakdown field strength (about 0.3 MV / cm) and high on-resistance, have become bottlenecks for further improving performance.

[0003] In order to overcome these limitations, it is urgent to explore new materials and technologies to develop more efficient power diodes. As a wide bandgap oxide semiconductor material, Ga2O3 has received widespread attention in recent years due to its strong electronic interaction. Ga2O3 has five isomers, namely α, β, γ, δ and ε phases, showing very rich physical and chemical properties. β -Ga2O3 is the isomer of Ga2O3 with the best thermal stability. Currently, Ga2O3 grown by the melting method is in the β phase. β -Ga2O3 has a theoretical breakdown electric field strength of up to 8 MV / cm, which is much higher than silicon and other traditional semiconductor materials. β -Ga2O3 power devices can operate at higher voltage levels while maintaining lower on-resistance. β -Ga2O3 also has excellent thermal and chemical stability, which makes it an ideal candidate material for the next generation of high-performance power electronic devices.

[0004] although β -Ga2O3 has shown great potential, but it still faces some challenges in practical application. β -In the study of Ga2O3 Schottky diodes, the breakdown voltage of general devices is difficult to reach the theoretical value of Ga2O3 materials. One of the main reasons is that the device is prone to electric field concentration at corners and edges, that is, the electric field concentration effect, which causes the electric field lines there to be too dense, and finally the device will break down prematurely in these areas. To solve this problem, researchers have proposed a variety of strategies, including field plates, trench metal-oxide-semiconductors, mesa terminations, and injected high-resistance edge termination technologies, to approach β-The theoretical limit of Ga2O3 Schottky diodes. However, even with these technologies, the breakdown voltage of actual devices is still difficult to reach the theoretical value. β -The p-type epitaxial growth and p-type ion implantation technologies in Ga2O3 materials are not yet mature, which directly limits the development of β The development of bipolar devices based on -Ga2O3, such as pn junction diodes, heterojunction field-effect transistors, etc., requires both high-quality n-type and p-type regions to achieve optimal performance, which not only affects the overall performance of the device, but also limits the realization of complex circuit structures, which is crucial for building fully integrated power electronic systems.

[0005] By combining with other p-type materials (such as NiO, Cu2O and SnO, etc.) to form a heterojunction structure, it can compensate for the β -Ga2O3 itself has insufficient p-type doping. Among them, Kokubun et al. reported the first full oxide using lithium-doped NiO in 2016. β -Ga2O3-based pn heterojunction (Kokubun et al . Appl. Phys. Express, 2016,9(9): 091101). Since then, NiO / β -Ga2O3 heterojunction diodes have been widely studied. The electric field concentration is suppressed by using sputtered continuous NiO film as edge termination. In addition, other materials with good p-type properties have also been introduced, such as Cu2O / β -Ga2O3 heterojunction barrier diode (Watahiki et al. Appl. Phys. Lett., 2017, 111(22):222104), IrO x / β -Ga2O3 heterojunction barrier diode (Zheng et al. IEEE Trans. on ElectronDevices, 2024, 71(3): 1587-1591.). As a p-type oxide, SnO has high mobility. The hole mobility of SnO is two orders of magnitude higher than that of NiO, which helps to improve the conductivity of the device. In addition, SnO has a direct band gap of about 2.9 eV, which is very suitable for high-voltage power diodes. Budde et al. used plasma-assisted molecular beam epitaxy (MBE) to β -Ga2O3 substrate to grow SnO and prepare vertical SnO / β -Ga2O3 heterojunction diode (Budde et al.Appl. Phys. Lett., 2020, 117(25), 252106). However, its breakdown voltage is only 66 V, which is due to the SnO / β -Ga2O3 heterojunction diode β -Ga2O3 does not have an epitaxial layer, which will have a significant impact on the performance of the device. The above are areas that urgently need improvement. Summary of the invention

[0006] Based on the above problems in the prior art, the present invention provides a SnO / β -Ga2O3 power diode and its preparation method, using Sn metal target as sputtering target, adopting radio frequency reactive magnetron sputtering technology, adjusting appropriate oxygen-argon ratio (Po), pressure and power, β -Ga2O3 surface reaction grows into SnO, using pn heterojunction structure, reducing β -The electric field concentration effect at the edge of the Ga2O3 anode improves β -Ga2O3-based power diode breakdown voltage, achieving high-performance power diodes.

[0007] In order to solve the technical problem, the present invention adopts the following technical solution: The present invention first discloses a SnO / β -Ga2O3 power diode, comprising a front side and a back side arranged oppositely β -Ga2O3 single crystal substrate, in the β -Ga2O3 single crystal substrate is provided on the front side β -Ga2O3 epitaxial layer, in the β A SnO layer is disposed on the Ga2O3 epitaxial layer, a metal anode is disposed on the SnO layer, and a β A metal cathode is provided on the back side of the Ga2O3 single crystal substrate.

[0008] As a preference: β -Ga2O3 single crystal substrate doping concentration is 10 18 ~10 19 cm -3 , thickness is 500~1000 μm; β -The doping concentration of the Ga2O3 epitaxial layer is 10 16 ~10 17 cm -3 , thickness is 5~20 μm.

[0009] Preferably, the SnO layer is prepared by using a high-purity Sn metal target as a sputtering target material, adopting a radio frequency reactive magnetron sputtering technology, sputtering and depositing in a mixed atmosphere of oxygen and argon to form a thin film, and then annealing.

[0010] Preferably, the SnO layer can be set to one of the following two structures: (1) The SnO layer is set to an integral structure (such as an integral circular structure) so that the metal anode and β -Ga2O3 epitaxial layer is not in contact with SnO β -Ga2O3 forms a heterojunction diode. In this structure, SnO and β -Ga2O3 are in direct contact, forming a heterojunction interface between the two, which can better ensure good rectification efficiency and lower reverse leakage current.

[0011] (2) The SnO layer is configured as a separate structure consisting of a plurality of SnO thin films arranged at intervals, and the metal anodes at the intervals are formed on β -Ga2O3 epitaxial layer, metal anode, SnO and β -Ga2O3 forms a heterojunction barrier diode. Furthermore, several SnO films in the separated structure are arranged in concentric rings (concentric circular rings or concentric square rings, etc.). The spacing width between adjacent SnO films is 3~5 μm, the width of the outermost SnO film is 10~30 μm, and the width of the remaining annular SnO films is 3~5 μm. This structure avoids the minority carrier storage effect existing in the traditional pn junction while maintaining a low forward voltage drop. In addition, the outermost SnO is wider and used as an edge terminal, which can effectively suppress β -Electric field concentration effect inside Ga2O3.

[0012] Preferably, the metal cathode adopts any one of a Ti / Au composite electrode, a Ti / Al / Ti / Au composite electrode and a Ti / Al / Ni / Au composite electrode with a total thickness of 100-300 nm, wherein the Ti layer thickness is 10-20 nm, the Al or Ni layer thickness is 10-30 nm, and the thickness remainder is the Au layer, and the desired composite electrode is formed by depositing the corresponding metals layer by layer.

[0013] Preferably, the metal anode is any one of a Ni / Au composite electrode and a Ni / Pt composite electrode with a total thickness of 100-300 nm, wherein the Ni layer thickness is 10-40 nm and the remaining thickness is the Au layer or the Pt layer, and the desired composite electrode is formed by depositing the corresponding metal layer by layer.

[0014] The present invention also provides the SnO / β-Ga2O3 power diode preparation method, the characteristics are: take the front side and set β -Ga2O3 epitaxial layer β -Ga2O3 single crystal substrate, after depositing a metal cathode on the back of the substrate and annealing, ultraviolet exposure lithography technology is used to β -Ga2O3 epitaxial layer is patterned by photolithography, and then the SnO layer is deposited by radio frequency reactive magnetron sputtering. After debonding and annealing, patterned photolithography is performed on the SnO layer again by UV exposure photolithography technology and a metal anode is deposited. Then, debonding and annealing are performed to produce SnO / β -Ga2O3 power diode. The specific steps include: Step 1: Take the front side and set β -Ga2O3 epitaxial layer β -Ga2O3 single crystal substrate, use Ar plasma at a power of 30-50W to clean the back of the substrate for 0.5-1 min; soak in H2O2 solution β -Ga2O3 epitaxial layer for 3-10 min, and then use O2 plasma at a power of 30-50 W to β -Ga2O3 epitaxial layer cleaning 0.5-1 min; Step 2: depositing a metal electrode on the back of the substrate, and then thermally annealing at 500-600° C. for 1-5 min in a N2 atmosphere to form a metal cathode; Step 3: UV exposure lithography β -Ga2O3 epitaxial layer was patterned and photolithography was performed to determine the position of the SnO layer. A Sn metal target was used as the sputtering target. RF reactive magnetron sputtering technology was used in a mixed atmosphere of oxygen and argon. β -Ga2O3 epitaxial layer is sputtered and deposited to form a thin film, then the adhesive is removed and annealed to obtain a SnO layer; the sputtering deposition conditions are: evacuating to a vacuum degree of 10 -4 Pa, controlling the oxygen flow rate to 2% of the total flow rate of oxygen and argon, adjusting the sputtering pressure to 0.4 Pa and the sputtering power to 50 W, obtaining a sputtering rate of 40 nm / min and a deposited film thickness of 80-120 nm; the annealing is a thermal annealing at 200°C for 10 min in a N2 atmosphere.

[0015] Step 4: Perform patterning photolithography on the SnO layer by UV exposure photolithography technology to determine the position of the metal anode, then deposit a metal electrode on the SnO layer, remove the glue, and then thermally anneal at 100-200°C for 1-5 min in a N2 atmosphere to form a metal anode, thus completing the SnO / β -Preparation of Ga2O3 power diodes.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The power diode of the present invention adopts a heterojunction structure or a heterojunction and Schottky parallel structure, and uses a pn heterojunction structure to reduce β -The electric field concentration effect at the edge of the Ga2O3 anode improves β -Ga2O3-based power diodes, achieving high-performance power diodes. β -Ga2O3 heterojunction diodes form a pn heterojunction barrier at the interface of the two materials due to the different energy band structures. The depletion region of the heterojunction is used to reduce the reverse leakage current of the power diode, improve the reliability and breakdown voltage of the device, and the heterojunction has a lower built-in potential, which is expected to reduce the on-state power consumption. β -Ga2O3 heterojunction barrier diode, in addition to two different semiconductor materials forming a heterojunction barrier, also includes a metal contact layer, this metal layer and β -Ga2O3 forms a Schottky barrier, and the Schottky junction will turn on before the pn heterojunction at a low forward voltage, resulting in a lower turn-on voltage, while the depletion region of the pn heterojunction will expand laterally to protect the Schottky contact from high reverse voltage, thereby reducing reverse leakage current and increasing breakdown voltage.

[0017] 2. The power diode of the present invention uses SnO as the p-type oxide layer, which has a direct band gap of 2.9 eV, which is beneficial to the application of power devices, and has a higher hole mobility (two orders of magnitude higher than NiO), which helps to improve the conductivity of the device. β -Ga2O3 forms high-performance power diodes.

[0018] 3. The device preparation process of the present invention is easy to manufacture. The SnO film is prepared by radio frequency reactive magnetron sputtering technology. This method can accurately control the thickness and uniformity of the film to ensure high-quality deposition. Radio frequency reactive magnetron sputtering technology can also achieve low-temperature growth, reduce thermal stress on the substrate, and improve the quality of the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The SnO / β -Schematic diagram of the structure of Ga2O3 power diode, in which the numbers 1 is the metal cathode, 2 is β -Ga2O3 single crystal substrate, 3 is β -Ga2O3 epitaxial layer, 4 is SnO layer, and 5 is metal anode.

[0020] Figure 2 This is the XRD spectrum of the SnO layer in Example 1.

[0021] Figure 3 The UV-visible absorption spectrum of the SnO layer in Example 1 and the fitted direct band gap spectrum of SnO are shown in FIG.

[0022] Figure 4 This is the UPS spectrum of the SnO layer in Example 1.

[0023] Figure 5 For SnO / β -Ga2O3 heterojunction band diagram.

[0024] Figure 6 The SnO / β -Voltage-current density characteristics of Ga2O3 heterojunction diode under forward bias.

[0025] Figure 7 The SnO / β -Voltage-current density characteristics of Ga2O3 heterojunction diode under reverse bias.

[0026] Figure 8 The SnO / β -Ga2O3 heterojunction diode device internal electric field simulation diagram under 500 V reverse bias.

[0027] Fig. 9 The SnO / β -Schematic diagram of the structure of Ga2O3 power diode. The numbers in the figure are: 1 is the metal cathode, 2 is β -Ga2O3 single crystal substrate, 3 is β -Ga2O3 epitaxial layer, 4 is SnO layer, and 5 is metal anode.

[0028] Fig.10 The SnO / β -Voltage-current density characteristics of Ga2O3 heterojunction barrier diode under forward bias.

[0029] Fig.11 The SnO / β -Voltage-current density characteristics of Ga2O3 heterojunction barrier diode under reverse bias.

[0030] Fig.12 The SnO / β -Ga2O3 heterojunction barrier diode device internal electric field simulation diagram under 500 V reverse bias.

[0031] Fig.13 This is the XPS spectrum of the SnO film prepared in Comparative Example 1 under the condition that the oxygen flow rate accounts for 5% of the total flow rate of oxygen and argon.

[0032] Fig.14 The XPS spectra of the SnO film in Comparative Example 2 at different temperatures. DETAILED DESCRIPTION

[0033] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0034] Example 1 See also Figure 1 , SnO / β -Ga2O3 power diode includes a front side and a back side that are arranged oppositely β -Ga2O3 single crystal substrate 2, β -Ga2O3 single crystal substrate is provided on the front side β -Ga2O3 epitaxial layer 3, in β A SnO layer 4 is arranged on the Ga2O3 epitaxial layer, a metal anode 5 is arranged on the SnO layer, and β A metal cathode 1 is arranged on the back side of the Ga2O3 single crystal substrate.

[0035] The SnO / β -Ga2O3 power diode is made as follows: 1. Set the front side β -Ga2O3 epitaxial layer β -Ga2O3 single crystal substrate, wherein: β -Ga2O3 single crystal substrate doping concentration is 6×10 18 cm -3 , thickness is 500 μm; β -The doping concentration of the Ga2O3 epitaxial layer is 2×10 16 cm -3 , thickness 10 μm. The substrate was ultrasonically cleaned in acetone, isopropanol, and deionized water for 10 min and then dried.

[0036] 2. Use Ar plasma to clean the back of the substrate at a power of 30 W for 30 s; soak in a 30% H2O2 solution. β -Ga2O3 epitaxial layer for 3 min, and then O2 plasma was used at a power of 30 W to β -Ga2O3 epitaxial layer cleaning for 30 s.

[0037] 3. Using electron beam evaporation technology, 20 nm Ti / 80 nm Au were deposited on the back of the substrate in sequence, followed by rapid thermal annealing at 540°C for 1 min in a N2 atmosphere to obtain a cathode electrode layer.

[0038] 4. Use UV exposure lithography technology β -Ga2O3 epitaxial layer, a circular pattern with a diameter of 100 μm was developed to deposit the SnO layer. The SnO layer was deposited on the photolithographic pattern by magnetron sputtering technology: the SnO layer used a Sn metal target with a purity of 99.99% as the sputtering target material, and the RF magnetron sputtering technology was used in a vacuum of 10 -4 Pa, the amount of O2 with a purity of 99.99% was controlled to be 1 SCCM, and the amount of Ar with a purity of 99.99% was controlled to be 49 SCCM. At this time, the oxygen flow rate accounted for 2% of the total flow rate of oxygen and argon. The sputtering pressure was adjusted to 0.4 Pa, the sputtering power was adjusted to 50 W, and the sputtering rate was 40 nm / min. After 2.5 min of deposition, a circular SnO film with a thickness of 100 nm and a diameter of 100 μm was obtained. The unexposed photoresist was removed with acetone, and then a rapid annealing furnace was used to thermally anneal at 200°C for 10 min in a N2 atmosphere to obtain the desired SnO layer.

[0039] 5. Use electron beam exposure lithography technology again to perform patterning on the SnO layer, and develop a circular pattern with a diameter of 50 μm for depositing the anode electrode. Use electron beam evaporation technology to deposit 30 nm Ni / 100 nm Au on the SnO layer in sequence. After removing the unexposed photoresist, use a rapid annealing furnace to anneal at 200°C in a N2 atmosphere for 10 min to obtain the anode electrode layer, thus completing the SnO / β -Preparation of Ga2O3 power diodes.

[0040] Figure 2 is the XRD pattern of the SnO film after annealing in step 4, which can be well identified as tetragonal SnO (JCPDS card number 06-0395).

[0041] Figure 3 The optical properties of the annealed SnO film are shown. The direct optical band gap of SnO is fitted to 2.9 eV based on the UV-visible absorption spectrum, which is consistent with the value reported in the literature (Ogo et al. Appl. Phys. Lett., 2008,93(3). 032113).

[0042] Figure 4The UPS spectrum of the SnO film after annealing shows that the secondary electron cutoff edge is located at about 5.1 eV through linear extrapolation of the edge, indicating that the work function of the SnO film is 5.1 eV. In addition, the valence band maximum (VBM) of the SnO film is determined to be about 1.0 eV, which means that the VBM is located 1.0 eV below the Fermi level, revealing the p-type conductivity of the SnO film.

[0043] Figure 5 Shows SnO / β -Ga2O3 heterojunction band diagram, considering β -Ga2O3 electron affinity (χ = 4 eV) and work function (W = 4.4 eV), it is expected that SnO thin films and β -Ga2O3 forms a type II heterojunction, showing a conduction band offset of 0.8 eV (△E C ). According to SnO and β -The Fermi level of Ga2O3 (E F ) and calculate the theoretical built-in potential (qV bi ) is about 0.7 eV. Therefore, β The electrons on the Ga2O3 side only need to overcome a 1.5 eV barrier to be injected into the SnO side. This is much faster than NiO / β -Ga2O3 heterojunction (3.6 eV) is much smaller (Gong et al. Appl. Phys. Lett., 2020, 117(2).022104), indicating that the on-state voltage is low. In addition, the Hall test showed that the conductivity type of SnO is p-type and the hole concentration is 5×10 17 cm -3 .

[0044] Figure 6 For SnO / β -Ga2O3 power diode forward characteristic curve, the results show that: SnO / β The turn-on voltage of the Ga2O3 heterojunction diode is 1.3 V and the specific on-resistance is 3.8 mΩ·cm 2 .

[0045] Figure 7 For SnO / β -Ga2O3 power diode reverse characteristic curve, the results show that: SnO / β -Ga2O3 heterojunction diode has a breakdown voltage of 1675 V. The device performance is better than other SnO / β -Ga2O3 power diodes have been significantly improved (Budde et al.Appl. Phys. Lett., 2020, 117(25), 252106).

[0046] Figure 8 For SnO / β -Ga2O3 power diode device internal electric field simulation diagram under 500 V bias. The results show that: adding SnO / β -Ga2O3 heterojunction diode, with the introduction of p-type SnO film, the electric field diffuses and the peak electric field at the anode edge is reduced to 2.0 MV / cm.

[0047] Example 2 See also Fig. 9 The device structure and preparation steps of this embodiment are the same as those of embodiment 1, the only difference being that the pattern of electron beam exposure lithography in step 4 is different. The SnO layer of this embodiment is composed of a number of concentric ring-shaped SnO films arranged at intervals. The outermost ring has an outer diameter of 200 μm and a width of 20 μm, which is used as a terminal extension. The width of the remaining rings is 3 μm, and the spacing between adjacent rings is 3 μm. Correspondingly, the anode in this embodiment is a circle with a diameter of 170 μm. This constitutes the SnO / β -Ga2O3 heterojunction barrier diode.

[0048] Fig.10 For SnO / β -Ga2O3 power diode forward characteristic curve, the results show that: SnO / β The turn-on voltage of the Ga2O3 heterojunction barrier diode is 1.0 V and the specific on-resistance is 5.1 mΩ·cm 2 .

[0049] Fig.11 For SnO / β -Ga2O3 power diode reverse characteristic curve, the results show that: SnO / β -The breakdown voltage of the Ga2O3 heterojunction barrier diode is 1375 V. Compared with Example 1, the performance of the prepared device has a lower breakdown voltage and a lower turn-on voltage.

[0050] Fig.12 For SnO / β -Ga2O3 heterojunction barrier diode device internal electric field simulation diagram under 500 V bias. The results show that: adding SnO / β -Ga2O3 heterojunction barrier diode has a breakdown field strength of 2.3 MV / cm. β-Ga2O3 heterojunction barrier diode terminal extension effectively suppresses the electric field concentration effect, presents a relatively uniform electric field in the structure, and reduces the peak electric field. β -The lateral depletion of the Ga2O3 pn junction narrows the current channel under the anode, which can shield the Schottky contact and reduce the reverse leakage current caused by the barrier lowering effect.

[0051] Comparative Example 1 This comparative example explores the conditions for depositing the SnO layer using RF magnetron sputtering technology. The difference from step 4 of Example 1 is that the O2 intake is regulated to 2.5 SCCM, the Ar intake with a purity of 99.99% is 47.5 SCCM, and the oxygen flow rate accounts for 5% of the total flow rate of oxygen and argon.

[0052] Fig.13 The XPS graph of the SnO film prepared in this comparative example shows that the binding energy peaks of the obtained film are located at 495 eV and 486.6 eV, which is consistent with the Sn 4+ The binding energy of the prepared film is the same, indicating that the prepared film is SnO2.

[0053] Comparative Example 2 This comparative example explored the variation trend of the SnO film (before annealing) deposited by RF magnetron sputtering technology in step 4 of Example 1 under different temperature conditions through variable temperature XPS test, such as Fig.14 As shown in Figure 2, when the temperature is raised from room temperature, it can be seen that the corresponding binding energies at 200°C are 494.3 eV and 485.9 eV, corresponding to Sn 2+ The binding energy of the film increases to 495 eV and 486.6 eV at 300 °C, indicating that the film is SnO. 4+ The binding energy of SnO2 is 0.

[0054] It can be seen from Comparative Examples 1 and 2 that controlling the conditions of magnetron sputtering, including the oxygen-argon ratio, pressure and power, and annealing temperature, is the key to producing a high-quality SnO layer.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A SnO / β -Ga2O3 power diode, characterized by: The SnO / β -Ga2O3 power diode includes a front side and a back side that are arranged oppositely β -Ga2O3 single crystal substrate, in the β -Ga2O3 single crystal substrate is provided on the front side β -Ga2O3 epitaxial layer, in the β A SnO layer is disposed on the Ga2O3 epitaxial layer, a metal anode is disposed on the SnO layer, and a β A metal cathode is provided on the back side of the Ga2O3 single crystal substrate.

2. SnO / according to claim 1 β -Ga2O3 power diode, characterized by: Said β -Ga2O3 single crystal substrate doping concentration is 10 18 ~10 19 cm -3 , thickness is 500~1000 μm; β -The doping concentration of the Ga2O3 epitaxial layer is 10 16 ~10 17 cm -3 , thickness is 5~20 μm.

3. SnO / according to claim 1 β -Ga2O3 power diode, characterized by: The SnO layer is obtained by using a Sn metal target as a sputtering target material, adopting a radio frequency reactive magnetron sputtering technology, sputtering and depositing in a mixed atmosphere of oxygen and argon to form a thin film, and then annealing.

4. SnO / according to claim 3 β -Ga2O3 power diode, characterized in that, The sputtering deposition conditions are: evacuating to a vacuum degree of 10 -4 Pa, controlling the oxygen flow rate to 2% of the total flow rate of oxygen and argon, adjusting the sputtering pressure to 0.4 Pa and the sputtering power to 50 W, obtaining a sputtering rate of 40 nm / min and a deposited film thickness of 80-120 nm; the annealing is a thermal annealing at 200°C for 10 min in a N2 atmosphere.

5. SnO / according to claim 1 or 3 β -Ga2O3 power diode, characterized by: The SnO layer is set as an integral structure so that the metal anode and β -Ga2O3 epitaxial layer is not in contact with SnO β -Ga2O3 forms a heterojunction diode; Alternatively, the SnO layer is configured as a separate structure consisting of a plurality of SnO thin films arranged at intervals, and the metal anodes at the intervals are formed on β -Ga2O3 epitaxial layer, metal anode, SnO and β -Ga2O3 forms a heterojunction barrier diode.

6. SnO / according to claim 1 β -Ga2O3 power diode, characterized by: The plurality of SnO films in the separated structure are arranged in concentric rings at intervals.

7. SnO / according to claim 1 β -Ga2O3 power diode, characterized by: The metal cathode adopts any one of a Ti / Au composite electrode, a Ti / Al / Ti / Au composite electrode and a Ti / Al / Ni / Au composite electrode with a total thickness of 100-300 nm, wherein the thickness of the Ti layer is 10-20 nm, the thickness of the Al or Ni layer is 10-30 nm, and the thickness remainder is the Au layer.

8. SnO / according to claim 1 β -Ga2O3 power diode, characterized by: The metal anode is any one of a Ni / Au composite electrode and a Ni / Pt composite electrode with a total thickness of 100-300 nm, wherein the Ni layer thickness is 10-40 nm, and the remaining thickness is the Au layer or the Pt layer.

9. A SnO / β -A method for preparing a Ga2O3 power diode, characterized in that: Take the front setting β -Ga2O3 epitaxial layer β -Ga2O3 single crystal substrate, after depositing a metal cathode on the back of the substrate and annealing, ultraviolet exposure lithography technology is used to β -Ga2O3 epitaxial layer, then SnO layer is deposited by RF reactive magnetron sputtering process, after debonding and annealing, patterned photolithography is performed on SnO layer again by UV exposure photolithography technology and metal anode is deposited, then debonding and annealing are performed to obtain SnO / β -Ga2O3 power diodes.

10. The preparation method according to claim 9, characterized in that: The steps include: Step 1: Take the front side and set β -Ga2O3 epitaxial layer β -Ga2O3 single crystal substrate, use Ar plasma at a power of 30-50 W to clean the back of the substrate for 0.5-1 min; soak in H2O2 solution β -Ga2O3 epitaxial layer for 3-10 min, and then use O2 plasma at a power of 30-50 W to β -Ga2O3 epitaxial layer cleaning 0.5-1 min; Step 2: depositing a metal electrode on the back of the substrate, and then thermally annealing at 500-600°C for 1-5 min in a N2 atmosphere to form a metal cathode; Step 3: UV exposure lithography β -Ga2O3 epitaxial layer was patterned and photolithography was performed to determine the position of the SnO layer. A Sn metal target was used as the sputtering target. RF reactive magnetron sputtering technology was used in a mixed atmosphere of oxygen and argon. β - After the Ga2O3 epitaxial layer is sputtered and deposited to form a thin film, the resist is removed and then annealed to obtain the SnO layer; Step 4: Perform patterning photolithography on the SnO layer by UV exposure photolithography technology to determine the position of the metal anode, then deposit a metal electrode on the SnO layer, remove the glue, and then thermally anneal at 100-200°C for 1-5 min in a N2 atmosphere to form a metal anode, thus completing the SnO / β -Preparation of Ga2O3 power diodes.

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