A ZnO-Si p-n junction piezoelectric device and its preparation method

Abstract

The present invention discloses a ZnO-Si p-n junction piezoelectric device and a preparation method thereof. The preparation method sequentially includes the following steps: depositing a zinc oxide seed layer on the surface of a substrate with a bottom electrode by radio frequency magnetron sputtering, then immersing it in a growth solution for soaking, and then cleaning and drying to obtain zinc oxide nanorods grown on the zinc oxide seed layer; depositing a p-type Si thin film by radio frequency magnetron sputtering; spin-coating an organic solvent dissolved with polymethyl methacrylate, then drying, and then depositing silver to obtain a ZnO-Si p-n junction piezoelectric device. The preparation method of the present invention is simple and easy to operate, and the prepared ZnO-Si p-n junction piezoelectric device has good piezoelectric performance. When the carrier concentration of the Si thin film is 7.88×10 18 cm ‑3 , its output voltage and current reach 0.8V and 40nA respectively.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric semiconductor material preparation, and particularly relates to a ZnO-Si p-n junction piezoelectric device and a preparation method thereof. Background Art

[0002] With the rapid development of flexible electronics technology, functional materials have made great progress in recent years. Among them, piezoelectric materials have been widely studied due to their excellent electromechanical coupling efficiency, fast response ability, and self-powered characteristics. In particular, piezoelectric semiconductor materials such as ZnO, GaN, and CdS have shown greater advantages than insulating piezoelectric materials in many fields due to the attractive coupling of piezoelectric and semiconductor characteristics, such as piezoelectric transistors, piezoelectronics, and piezoelectric photonics. However, the presence of intrinsic carriers in these materials causes a screening effect, which weakens the piezoelectric output, which is one of the main challenges currently faced. In the case of zinc oxide, under the action of an external force, the piezoelectric potential appears at both ends of the c-axis, but the directional migration of its intrinsic free carriers neutralizes the piezoelectric potential, thus weakening the piezoelectric output. For this reason, a lot of work has been done in improving the output performance of zinc oxide-based piezoelectric devices. Usually, forming a p-n junction through interface engineering has been proven to be an effective means to suppress the screening effect and improve the final electrical output of ZnO-based piezoelectric devices. A series of p-type semiconductor materials (such as CuI, NiO, PEDOT:PSS, P3HT) have been used to improve the piezoelectric performance by forming a p-n junction on the surface of ZnO nanorods (ZnO NRs). Theoretically, the characteristics of the p-n junction are not only related to the material type but also closely related to the carrier concentration of the material. However, there is a lack of a reasonable method to maximize the piezoelectric performance, and it is difficult to reasonably guide device design to obtain high-performance piezoelectric devices. Summary of the Invention

[0003] In order to solve the above technical problems, the object of the present invention is to provide a ZnO-Si p-n junction piezoelectric device and a preparation method thereof to solve the problems that the prior art cannot maximize the piezoelectric performance of the ZnO-Si p-n junction piezoelectric device and the piezoelectric device has poor sensitivity and stability.

[0004] The technical solution of the present invention to solve the above technical problems is as follows: A preparation method of a ZnO-Si p-n junction piezoelectric device is provided, which sequentially includes the following steps:

[0005] (1) On the surface of a substrate with a bottom electrode, deposit a zinc oxide seed layer by radio frequency magnetron sputtering, then immerse it in a growth solution at 80-90 °C for 5-8 h, and then wash and dry to obtain zinc oxide nanorods grown on the zinc oxide seed layer;

[0006] (2) On the surface of the zinc oxide nanorods prepared in step (1), deposit a p-type Si thin film by radio frequency magnetron sputtering;

[0007] (3) On the surface of the p-type Si thin film prepared in step (2), spin-coat an organic solvent dissolved with polymethyl methacrylate, then dry it, and then deposit silver to obtain a ZnO-Si p-n junction piezoelectric device.

[0008] The beneficial effects of the present invention are as follows: On the surface of the zinc oxide nanorods (ZnO NRs) obtained by hydrothermal growth, a p-type Si thin film is prepared by magnetron sputtering to form a p-n junction with the ZnO NRs. In the p-n junction region, free electrons in the ZnO NRs are bound and a built-in electric field is formed. These two strongly inhibit the shielding effect that causes the reduction of the piezoelectric output of the ZnO NRs, greatly improving the piezoelectric output of the ZnO NRs. In addition, due to the existence of the p-n junction capacitance, the total capacitance of the piezoelectric device is reduced. When the generated piezoelectric charge amount remains unchanged, the low capacitance of the piezoelectric device increases the piezoelectric output.

[0009] On the basis of the above technical solutions, the present invention can be further improved as follows:

[0010] Further, in step (1), the bottom electrode is indium tin oxide.

[0011] Further, in step (1), the substrate is PEN plastic.

[0012] Further, in step (1), after cleaning the substrate with the bottom electrode with deionized water and ethanol, deposit a zinc oxide seed layer.

[0013] Further, in step (1), the growth solution is prepared by the following method: Dissolve zinc nitrate hexahydrate and hexamethylenetetramine in water to obtain the growth solution; wherein, the concentrations of zinc nitrate hexahydrate and hexamethylenetetramine in the growth solution are both 0.05 - 0.1 mol / L.

[0014] Further, the concentrations of zinc nitrate hexahydrate and hexamethylenetetramine in the growth solution are both 0.075 mol / L.

[0015] Further, in step (1), the conditions for radio frequency magnetron sputtering are: working pressure 1.8 - 2.2 Pa, RF power 55 - 65 W, gas flow rate �5 - 45 sccm.

[0016] Further, in step (1), immerse it in the growth solution at 85 °C for 6 h.

[0017] Further, in step (1), use deionized water for cleaning.

[0018] Further, in step (1), dry it at 45 - 55 °C for 2.5 - 3.5 h.

[0019] Further, in step (2), the precursor for depositing the p-type Si thin film is a boron-doped silicon target.

[0020] Further, the resistivity of the silicon target is 0.01 - 10 Ω·cm.

[0021] Further, in step (2), the conditions for radio frequency magnetron sputtering are: working pressure 1.2 - 1.8 Pa, RF power 90 - 110 W, and gas flow rate 28 - 32 sccm.

[0022] Further, in step (3), the concentration of polymethyl methacrylate in the organic solvent is 8 - 12 wt%.

[0023] Further, the organic solvent is N,N-dimethylformamide.

[0024] Further, in step (3), it is dried at 65 - 75 °C for 2.5 - 3.5 h.

[0025] Further, in step (3), vacuum coating is adopted, and silver is deposited for 2 - 4 min under the conditions of a pressure of 5 - 10×10 -4 Pa and a current of 100 - 150 A.

[0026] The present invention also provides a ZnO-Si p-n junction piezoelectric device prepared by the preparation method of the above ZnO-Si p-n junction piezoelectric device.

[0027] The present invention has the following beneficial effects:

[0028] 1. The preparation method of the present invention is simple and easy to operate, and the prepared ZnO-Si p-n junction piezoelectric device has good piezoelectric performance.

[0029] 2. When the carrier concentration of the Si thin film is 7.88×10 18 cm -3 , its output voltage and current reach 0.8 V and 40 nA respectively.

[0030] 3. The sensitivity of the ZnO-Si p-n junction piezoelectric device of the present invention is 299.3 - 384.7 mV Mpa -1 , and it has high mechanical stability and durability. Description of the Drawings

[0031] Figure 1 It is the surface SEM image of the zinc oxide nanorods prepared in Example 2;

[0032] Figure 2 It is the cross-sectional SEM image of the zinc oxide nanorods prepared in Example 2;

[0033] Figure 3 SEM image of the ZnO-Si p-n junction prepared in Example 2;

[0034] Figure 4 M-s curve of the p-type Si thin film prepared in Examples 1-2;

[0035] Figure 5 M-s curve of the p-type Si thin film prepared in Example 3 and pure ZnO prepared in Comparative Example 1;

[0036] Figure 6 M-s curve of the p-type Si thin film prepared in Comparative Examples 2-3;

[0037] Figure 7 Carrier concentration and built-in electric field diagrams of the piezoelectric devices prepared in Examples 1-3 and Comparative Examples 2-3;

[0038] Figure 8 Output voltage diagrams of the piezoelectric devices prepared in Examples 1-3 and Comparative Examples 1-3;

[0039] Figure 9 Output current diagrams of the piezoelectric devices prepared in Examples 1-3 and Comparative Examples 1-3;

[0040] Figure 10 Polarity reversal test diagram of the ZnO-Si p-n junction piezoelectric device prepared in Example 2;

[0041] Figure 11 Diagram of the effect of pressure on the output voltage of the piezoelectric devices prepared in Examples 1-3 and Comparative Examples 1-3;

[0042] Figure 12 Sensitivity diagrams of the piezoelectric devices prepared in Examples 1-3 and Comparative Examples 1-3;

[0043] Figure 13 Stability test diagram of the piezoelectric device prepared in Example 2;

[0044] Figure 14 Curve of piezoelectric performance varying with carrier concentration;

[0045] Figure 15 For Figure 15 Comsol simulation result diagram;

[0046] Figure 16 Electrochemical impedance spectrum diagram of the pure ZnO piezoelectric device prepared in Comparative Example 1;

[0047] Figure 17 Electrochemical impedance spectrum diagrams of the piezoelectric devices prepared in Examples 1-3 and Comparative Examples 2-3;

[0048] Figure 18Resistance and capacitance diagrams of the piezoelectric devices prepared in Examples 1-3 and Comparative Examples 1-3. Detailed implementation mode

[0049] The principles and features of the present invention will be described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. For those conditions not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained by purchasing in the market.

[0050] Example 1:

[0051] A preparation method of a ZnO-Si p-n junction piezoelectric device includes the following steps:

[0052] (1) Use deionized water and ethanol to treat a PEN plastic substrate with indium tin oxide (ITO). ITO is used as the bottom electrode. Deposit a zinc oxide seed layer on ITO by radio frequency magnetron sputtering. The conditions of radio frequency magnetron sputtering are: working pressure 1.8 Pa, RF power 55 W, gas flow rate 35 sccm. Then, at 80 °C, immerse it in the growth solution for 8 h, then wash it with ionized water and put it into an oven to dry at 45 °C for 3.5 h to obtain zinc oxide nanorods (ZnO NRs) grown on the zinc oxide seed layer; among them, the growth solution is prepared by the following method: dissolve zinc nitrate hexahydrate and hexamethylenetetramine in water to prepare the growth solution; the concentrations of zinc nitrate hexahydrate and hexamethylenetetramine in the growth solution are both 0.05 mol / L;

[0053] (2) Use a boron-doped silicon target with a resistivity of 10 Ω·cm as the precursor, and deposit a p-type Si thin film on the surface of the zinc oxide nanorods (ZnO NRs) prepared in step (1) by radio frequency magnetron sputtering. The conditions of radio frequency magnetron sputtering are: working pressure 1.2 Pa, RF power 90 W, gas flow rate 28 sccm;

[0054] (3) Spin-coat an organic solvent in which 8 wt% of polymethyl methacrylate (PMMA) is dissolved on the surface of the p-type Si thin film prepared in step (2), then put it into an oven and dry it at 65 °C for 3.5 h. PMMA is used as the insulating layer, and then vacuum coating is carried out. Under the conditions of a pressure of 5×10 -4 Pa and a current of 100 A, deposit silver for 2 min. Silver is used as the top electrode to obtain a ZnO-Si p-n junction piezoelectric device.

[0055] Example 2:

[0056] A preparation method of a ZnO-Si p-n junction piezoelectric device includes the following steps:

[0057] (1) A PEN plastic substrate with indium tin oxide (ITO) is treated with deionized water and ethanol. The ITO serves as the bottom electrode. A zinc oxide seed layer is deposited on the ITO by radio frequency magnetron sputtering. The conditions for radio frequency magnetron sputtering are: working pressure 2 Pa, RF power 60 W, gas flow rate 40 sccm. Then, it is immersed in the growth solution at 85 °C for 6 h, washed with ionized water, and placed in an oven to be dried at 50 °C for 3 h, obtaining zinc oxide nanorods (ZnO NRs) grown on the zinc oxide seed layer. Among them, the growth solution is prepared by the following method: zinc nitrate hexahydrate and hexamethylenetetramine are dissolved in water to prepare the growth solution. The concentrations of zinc nitrate hexahydrate and hexamethylenetetramine in the growth solution are both 0.075 mol / L;

[0058] (2) Using a boron-doped silicon target with a resistivity of 0.1 Ω·cm as the precursor, a p-type Si thin film is deposited on the surface of the zinc oxide nanorods (ZnO NRs) prepared in step (1) by radio frequency magnetron sputtering. The conditions for radio frequency magnetron sputtering are: working pressure 1.5 Pa, RF power 100 W, gas flow rate 30 sccm;

[0059] (3) An organic solvent in which 10 wt% of polymethyl methacrylate (PMMA) is dissolved is spin-coated on the surface of the p-type Si thin film prepared in step (2), and then placed in an oven to be dried at 70 °C for 3 h. The PMMA serves as the insulating layer. Then, vacuum coating is used to deposit silver for 3 min under the conditions of a pressure of 8×10 -4 Pa and a current of 130 A. The silver serves as the top electrode, obtaining a ZnO-Si p-n junction piezoelectric device.

[0060] Example 3:

[0061] A method for preparing a ZnO-Si p-n junction piezoelectric device, comprising the following steps:

[0062] (1) A PEN plastic substrate with indium tin oxide (ITO) is treated with deionized water and ethanol. The ITO serves as the bottom electrode. A zinc oxide seed layer is deposited on the ITO by radio frequency magnetron sputtering. The conditions for radio frequency magnetron sputtering are: working pressure 2.2 Pa, RF power 65 W, gas flow rate 45 sccm. Then, it is immersed in the growth solution at 90 °C for 5 h, washed with ionized water, and placed in an oven to be dried at 55 °C for 2.5 h, obtaining zinc oxide nanorods (ZnO NRs) grown on the zinc oxide seed layer. Among them, the growth solution is prepared by the following method: zinc nitrate hexahydrate and hexamethylenetetramine are dissolved in water to prepare the growth solution. The concentrations of zinc nitrate hexahydrate and hexamethylenetetramine in the growth solution are both 0.1 mol / L;

[0063] (2) Using a boron-doped silicon target with a resistivity of 0.01 Ω·cm as a precursor, deposit a p-type Si thin film on the surface of the zinc oxide nanorods (ZnO NRs) prepared in step (1) by radio frequency magnetron sputtering. The conditions for radio frequency magnetron sputtering are as follows: working pressure 1.8 Pa, RF power 110 W, gas flow rate 32 sccm;

[0064] (3) Spin-coat an organic solvent dissolved with 12 wt% polymethyl methacrylate (PMMA) on the surface of the p-type Si thin film prepared in step (2), then place it in an oven and dry it at 75 °C for 3.5 h. PMMA serves as the insulating layer. Then, use vacuum coating to deposit silver for 4 min under the conditions of a pressure of 10×10 -4 Pa and a current of 150 A. Silver serves as the top electrode to fabricate the ZnO-Si p-n junction piezoelectric device.

[0065] Comparative Example 1:

[0066] A preparation method of a pure ZnO piezoelectric device, comprising the following steps:

[0067] Without step (2), the rest is the same as in Example 1.

[0068] Comparative Example 2:

[0069] A preparation method of a ZnO-Si p-n junction piezoelectric device, comprising the following steps:

[0070] In step (2), the resistivity of the boron-doped silicon target is 1000 Ω·cm, and the rest is the same as in Example 1.

[0071] Comparative Example 3:

[0072] A preparation method of a ZnO-Si p-n junction piezoelectric device, comprising the following steps:

[0073] In step (2), the resistivity of the boron-doped silicon target is 40 Ω·cm, and the rest is the same as in Example 1.

[0074] Test Example

[0075] I. Detect the zinc oxide nanorods prepared in step (1) of Example 2 by scanning electron microscopy, and the results are shown in Figure 1-2 . It can be seen from Figure 1-2 that the zinc oxide nanorods were successfully prepared in the present invention.

[0076] II. Detect the ZnO-Si p-n junction of the piezoelectric device prepared in step (2) of Example 2 by scanning electron microscopy, and the results are shown in Figure 3 (a is a plan view, b is a cross-sectional view). It can be seen from Figure 3 that the ZnO-Si p-n junction was successfully fabricated in the present invention.

[0077] III. The M - s curves of the p - type Si thin films prepared in Examples 1 - 3 and Comparative Examples 2 - 3 and the ZnO NRs prepared in Comparative Example 1 were detected. The specific detection method was as follows: Using a Chenhua 660e electrochemical workstation, testing was carried out in a 0.5 mol / L Na2SO4 solution. The reference electrode was selected as Ag / AgCl. The amplitude of the applied alternating current was 50 mV and the frequency was 5 kHz. The results are shown in Figures 4-6 . According to the M - S equation, from Figures 4-6 calculate the carrier concentration and built - in electric field of the p - type Si thin film. The results are shown in Figure 7 . From Figure 7 it can be seen that the carrier concentrations of Examples 1 - 3 of the present invention are 1.32×10 18 cm -3 , 7.88×10 18 cm -3 and 1.44×10 19 cm -3 respectively, while the carrier concentrations of Comparative Examples 2 - 3 are 2.04×10 17 cm -3 and 4.77×10 17 cm -3 respectively. The built - in electric fields of Examples 1 - 3 are 0.4840 V, 0.5202 V and 0.5458 respectively, while the built - in electric fields of Comparative Examples 2 - 3 are 0.4359 V and 0.4578 V respectively. This shows that when using the boron - doped silicon target with a resistivity of 0.01 - 10 Ω·cm of the present invention as a precursor, the prepared ZnO - Si p - n junction piezoelectric device has a higher carrier concentration and built - in electric field.

[0078] IV. Piezoelectric performance test

[0079] 1. The output voltage and current of the piezoelectric devices prepared in Examples 1 - 3 and Comparative Examples 1 - 3 were detected. The specific detection method was as follows: Using a linear motor to provide periodic pressure, using a Mark - 10 dynamometer to record the magnitude of the force, measuring the piezoelectric output voltage and current of the piezoelectric device under 2 MPa and an effective area of 9 mm 2 . The results are shown in Figures 8-9 . From Figures 8-9It can be seen that the output voltage and current of the pure ZnO piezoelectric device prepared in Comparative Example 1 are relatively low, being 0.075 V and 10 nA respectively, which is mainly attributed to the shielding effect caused by a large number of free electrons existing in the ZnO NRs; although the output voltage and current of the ZnO-Si p-n junction piezoelectric devices prepared in Comparative Examples 2-3 are higher than those of the pure ZnO piezoelectric device prepared in Comparative Example 1, however, through interface engineering, the ZnO-Si p-n junction piezoelectric device prepared in the present invention has achieved a significant improvement in piezoelectric output by suppressing the shielding effect. Especially for the piezoelectric device prepared in Example 2, when the carrier concentration of the Si thin film is 7.88×10 18 cm -3 , its output voltage and current reach 0.8 V and 40 nA respectively.

[0080] 2. The ZnO-Si p-n junction piezoelectric device prepared in Example 2 was subjected to a polarity inversion test. The specific test method is as follows: The positive and negative interfaces of the Keithley 6514 were respectively connected to the device in the forward and reverse directions. The results are shown in Figure 10 . It can be seen from Figure 10 that the electrical signal comes from the piezoelectric effect rather than the interference of the test system.

[0081] 3. The piezoelectric devices prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to a test on the variation of voltage output with pressure. The specific test method is as follows: Control the linear motor (HS01-37×166) to apply a pressure perpendicular to the sample, and then use the Keithley 6514 to collect the open-circuit voltage signal generated by our device in real time. The results are shown in Figure 11 . It can be seen from Figure 11 that the output voltage of the piezoelectric device prepared in the present invention increases with the increase of pressure, showing good linearity. This is because at a greater pressure, the ZnO NRs generate a greater deformation.

[0082] 4. The piezoelectric devices prepared in Examples 1-3 and Comparative Examples 1-3 were used to Figure 11 calculate the sensitivity. The results are shown in Figure 12 . It can be seen from Figure 12 that the sensitivity of the piezoelectric device prepared in the present invention is 299.3-384.7 mV Mpa -1 , while the sensitivity of the piezoelectric devices prepared in Comparative Examples 1-3 is relatively low.

[0083] 5. The ZnO-Si p-n junction piezoelectric device prepared in Example 2 was subjected to a stability test. The specific test method is as follows: Control the linear motor (HS01-37×166) to apply 2700 periodic pressures perpendicular to the sample, and then use the Keithley 6514 to collect the open-circuit voltage signal generated by our device in real time. The results are shown in Figure 13 . It can be seen from Figure 13It can be seen that after 2,700 cycles, the output voltage of the piezoelectric device basically remains unchanged, indicating that the ZnO-Si p-n junction piezoelectric device prepared by the present invention has high mechanical stability and durability.

[0084] V. Test for maximizing piezoelectric performance

[0085] 1. As can be seen from Figure 8 , the output voltage of the ZnO-Si p-n junction piezoelectric device shows a trend of first increasing and then slightly decreasing with the increase of the carrier concentration of the p-type semiconductor. This is because as the carrier concentration of the Si film increases, the suppression of the shielding effect becomes more obvious, and the piezoelectric output shows an obvious increasing trend as Figure 14 shown. However, the piezoelectric potential of the ZnO-Si p-n junction piezoelectric device does not always increase with the increase of the carrier concentration.

[0086] 2. Perform Comsol simulation on Figure 14 , and the results are shown in Figure 15 . As can be seen from Figure 15 , as the carrier concentration in the ZnO NRs decreases, the piezoelectric potential first increases significantly and then tends to be stable. This indicates that when the carrier concentration is lower than a certain level, the shielding effect on the piezoelectric potential of the ZnO NRs can be ignored (it can be considered that the shielding effect is ineffective); at the same time, when the carrier concentration continuously increases, the equivalent resistance decreases and the total capacitance increases. Undoubtedly, a larger capacitance is not conducive to high piezoelectric output. At the same piezoelectric charge density, a lower device capacitance can increase the piezoelectric potential.

[0087] 3. Perform electrochemical impedance detection on the piezoelectric devices prepared in Examples 1-3 and Comparative Examples 1-3. The specific detection method is as follows: Measured using the AC Impedance module of the Chenhua 660e electrochemical workstation with a two-electrode system, and the results are shown in Figures 16-17 . Two typical semicircle diagrams with negative virtual impedance indicate the presence of an RC circuit, where the equivalent resistance R is close to the diameter of the arc. Combining the characteristic frequency f c , the total device capacitance C can be calculated (τ = RC = 1 / 2πf c ), and Figure 18 can be obtained. As can be seen from Figure 18It can be seen that as the carrier concentration of the p-type Si thin film increases, the equivalent resistance decreases and the total capacitance increases, which is undoubtedly unfavorable for piezoelectric output. As the carrier concentration of the p-type Si thin film continues to increase, the reduction of the piezoelectric output caused by the device capacitance exceeds the enhancement of the shielding effect on the piezoelectric output suppression, resulting in the decrease of the final output of the device. Therefore, the piezoelectric output tends to increase and then decrease from Comparative Example 2 to Example 3, and reaches the maximum value at Example 2. By simultaneously considering the effects of the shielding effect and the device capacitance on the output and matching the carrier concentration of the Si thin film, when the carrier concentration of the Si thin film is relatively high but not the highest (i.e., 7.88×10 18 cm -3 ), the best piezoelectric performance of 0.8 V and 40 nA is obtained, which provides a theoretical method for maximizing the piezoelectric performance and reasonably guides the device design to obtain high-performance piezoelectric devices.

[0088] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a ZnO-Si p-n junction piezoelectric device, characterized in that, It successively includes the following steps: (1) On the surface of a substrate with a bottom electrode, deposit a zinc oxide seed layer by radio frequency magnetron sputtering, then immerse it in a growth solution at 80 - 90 °C for 5 - 8 h, and then clean and dry it to obtain zinc oxide nanorods grown on the zinc oxide seed layer; (2) Deposit a p-type Si thin film on the surface of the zinc oxide nanorods obtained in step (1) by radio frequency magnetron sputtering; (3) Spin-coat an organic solvent dissolved with polymethyl methacrylate on the surface of the p-type Si thin film obtained in step (2), then dry it, and then deposit silver to obtain a ZnO-Si p-n junction piezoelectric device; In step (2), the precursor for depositing the p-type Si thin film is a boron-doped silicon target; The resistivity of the silicon target is 0.01 - 10 Ω·cm; In step (2), the conditions for radio frequency magnetron sputtering are: working pressure 1.2 - 1.8 Pa, RF power 90 - 110 W, gas flow rate 28 - 32 sccm.

2. The preparation method of the ZnO-Si p-n junction piezoelectric device according to claim 1, wherein In step (1), the bottom electrode is indium tin oxide.

3. The preparation method of the ZnO-Si p-n junction piezoelectric device according to claim 1, characterized in that, In step (1), the growth solution is prepared by the following method: Dissolve zinc nitrate hexahydrate and hexamethylenetetramine in water to obtain the growth solution; wherein, the concentrations of zinc nitrate hexahydrate and hexamethylenetetramine in the growth solution are both 0.05 - 0.1 mol / L.

4. The preparation method of the ZnO-Si p-n junction piezoelectric device according to claim 1, characterized in that, In step (1), the conditions for radio frequency magnetron sputtering are: working pressure 1.8 - 2.2 Pa, RF power 55 - 65 W, gas flow rate 35 - 45 sccm.

5. The preparation method of the ZnO-Si p-n junction piezoelectric device according to claim 1, characterized in that, In step (3), the concentration of polymethyl methacrylate in the organic solvent is 8 - 12 wt%.

6. The preparation method of the ZnO-Si p-n junction piezoelectric device according to claim 1, characterized in that, In step (3), vacuum coating is used, and silver is deposited for 2 - 4 min under the conditions of a pressure of 5 - 10×10-4 Pa and a current of 100 - 150 A.

7. A ZnO-Si p-n junction piezoelectric device prepared by the method for preparing a ZnO-Si p-n junction piezoelectric device according to any one of claims 1 - 6.

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