阅读说明：本技术 一种SiC/ZnO纳米异质结压力传感器及其制备方法 (SiC/ZnO nano heterojunction pressure sensor and preparation method thereof ) 是由 王霖 吴杰 高凤梅 陈善亮 杨为佑 于 2020-02-24 设计创作，主要内容包括：本发明属于传感器技术领域,涉及一种SiC/ZnO纳米异质结压力传感器及其制备方法。所述SiC/ZnO纳米异质结压力传感器的制备方法包括以下步骤：(1)制备SiC/ZnO纳米异质结：将SiC纳米线分散于乙醇溶液中,取含有SiC纳米线的乙醇溶液滴在Si片上,自然晾干；然后将载有SiC纳米线的Si片面朝上放入原子层沉积系统,在惰性气氛中,以二乙基锌和水作为生长ZnO层的前驱体,在SiC纳米线表面生长ZnO层,从而获得SiC/ZnO纳米异质结；(2)压力传感器构建：将载有SiC/ZnO纳米异质结的Si片,在原子力显微镜导电模式下构建Pt/Ir-SiC/ZnO-Si压力传感器。(The invention belongs to the technical field of sensors, and relates to a SiC/ZnO nano heterojunction pressure sensor and a preparation method thereof. The preparation method of the SiC/ZnO nano heterojunction pressure sensor comprises the following steps: (1) preparing a SiC/ZnO nano heterojunction: dispersing the SiC nanowires in an ethanol solution, dripping the ethanol solution containing the SiC nanowires on a Si wafer, and naturally airing; then putting the Si sheet carrying the SiC nanowire with the upward surface into an atomic layer deposition system, and growing a ZnO layer on the surface of the SiC nanowire by taking diethyl zinc and water as precursors for growing the ZnO layer in an inert atmosphere, thereby obtaining the SiC/ZnO nano heterojunction; (2) constructing a pressure sensor: and constructing the Pt/Ir-SiC/ZnO-Si pressure sensor on the Si sheet carrying the SiC/ZnO nano heterojunction in an atomic force microscope conduction mode.)

1. The pressure sensor is characterized by comprising a Si sheet substrate, a functional unit and a probe, wherein the functional unit is loaded on the Si sheet substrate, the functional unit is a SiC/ZnO nano heterojunction, and the plating layer of the probe tip is Pt/Ir.

2. The pressure sensor of claim 1, wherein the SiC/ZnO nano-heterojunction comprises a SiC nanowire and a ZnO nanolayer covering a surface of the SiC nanowire.

3. The pressure sensor according to claim 2, wherein the SiC nanowire has a diameter of 200 nm and a length of 5-30 μm.

4. A pressure sensor as claimed in claim 2, characterized in that the ZnO nanolayers are 10-30nm thick.

5. A pressure sensor as claimed in claim 2, characterized in that the ZnO nanolayers are 18-22nm thick.

6. The method of preparing the SiC/ZnO nano heterojunction pressure sensor of claim 1, wherein the method of preparing comprises the steps of:

(1) preparing a SiC/ZnO nano heterojunction:

dispersing the SiC nanowires in an ethanol solution, dripping the ethanol solution containing the SiC nanowires on a Si wafer, and naturally airing;

then putting the Si sheet carrying the SiC nanowire with the upward surface into an atomic layer deposition system, and growing a ZnO nano layer on the surface of the SiC nanowire by taking diethyl zinc and water as precursors for growing the ZnO nano layer in an inert atmosphere, thereby obtaining the SiC/ZnO nano heterojunction;

(2) constructing a pressure sensor:

and constructing the Pt/Ir-SiC/ZnO-Si pressure sensor on the Si sheet carrying the SiC/ZnO nano heterojunction in an atomic force microscope conduction mode.

7. The method for preparing the pressure sensor according to claim 6, wherein the SiC nanowire is one or more of an undoped SiC nanowire, an N-doped SiC nanowire and a P-doped SiC nanowire.

8. The method for preparing a pressure sensor according to claim 6, wherein the method for preparing the N-doped SiC nanowire comprises the following steps:

heat crosslinking curing and crushing polysilazane, and then putting the polysilazane into a graphite crucible;

placing a carbon fiber cloth substrate loaded with a catalyst on the top of a graphite crucible;

and placing the graphite crucible in an atmosphere sintering furnace, vacuumizing the atmosphere sintering furnace to 1-5Pa, introducing protective atmosphere, and sintering under the protective atmosphere to obtain the N-doped SiC nanowire.

9. The method for preparing a pressure sensor according to claim 8, wherein the catalyst is one or more of cobalt nitrate, nickel nitrate, ferric nitrate and nickel sulfate.

10. The method as claimed in claim 8, wherein the deposition temperature of the atomic layer deposition system is 150-200 ℃.

Technical Field

The invention belongs to the technical field of sensors, and relates to a SiC/ZnO nano heterojunction pressure sensor and a preparation method thereof.

Background

The sensor technology is one of the key technologies for measuring the modernization process, and with the progress of silicon, micro-machining technology, ultra-large integrated circuit technology and material preparation and characteristic research work, the pressure sensor has wide application prospect in the fields of biomedicine, micromachine and the like. Among many sensors, semiconductor pressure sensors are attracting attention for their excellent performance.

The low-dimensional nano material is considered to have larger pressure resistance performance because of the unique morphology and structure. To date, the nano-carbon tube, Si nano-material, ZnO nano-structure, nano-graphene structure, SiC nano-structure and Si₃N₄The piezoresistive properties of materials such as nanoribbons have been studied. Particularly in 2006, the piezoresistive effect of the Si nanowire is reported for the first time, the Si nanowire has a strain coefficient of 5000, the piezoresistive factor is nearly 50 times of that of the bulk material of the Si nanowire, and the research heat tide of a semiconductor low-dimensional nano material pressure sensor is stimulated globally. Further proves that the pressure sensor with excellent performance is hopeful to be obtained by taking the semiconductor low-dimensional nano material as a functional unit.

Silicon carbide (SiC) is the third generation of wide band gap semiconductor material with the most potential development at present, and has wide band gap, high electron drift rate, high thermal conductivity, high electron mobility, higher breakdown voltage, and excellent mechanical property and chemical stability, and can be used at high temperature, high frequency and in high frequencyAt present, a great deal of work at home and abroad reports the piezoresistive property of the SiC low-dimensional nanostructure, for example, the SiC nano film has about 5.05 × 10^-11Pa^-1The piezoresistive coefficient of (a). The piezoresistive coefficient of single SiC or doped SiC is still small, and the requirement of a device with higher precision cannot be met.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide the SiC/ZnO nano heterojunction pressure sensor and the preparation method thereof.

One of the objects of the present invention can be achieved by the following technical solutions:

the utility model provides a SiC/ZnO nanometer heterojunction pressure sensor, pressure sensor includes the Si piece base, loads functional unit and probe on the Si piece base, the functional unit is SiC/ZnO nanometer heterojunction, probe tip cladding material is Pt/Ir.

Preferably, the SiC/ZnO nano heterojunction comprises a SiC nanowire and a ZnO nano layer covering the surface of the SiC nanowire.

The surface of the SiC nanowire is covered with the ZnO nanolayer, and the piezoresistive effect of the SiC nanowire and the piezoelectric effect of the ZnO nanolayer are effectively coupled. When the probe tip contacts with the surface of the ZnO nano layer, strain is generated, polarization charges are generated in the ZnO, positive and negative voltage polarization charges are respectively generated on the bottom surface and the top surface in the ZnO nano layer, and therefore a built-in polarized electric field can be formed. Thus, current flows from the SiC nanowire to the probe tip under a forward bias, and free electrons flow through the potential barrier in the opposite direction. Considering that the electric field direction of the built-in polarization electric field is consistent with the direction of the applied electric field, electrons inside the ZnO nanolayer will also have the same transport direction as external electrons. Therefore, the current of the SiC/ZnO nano heterojunction under the positive bias voltage is obviously increased. In addition, the deposited ZnO nanolayer may serve as an effective electron transport channel due to high carrier mobility, may reduce carrier recombination between the SiC nanowire and the ZnO nanolayer, and promote carrier migration, and ultimately leads to a significant increase in current. In conclusion, the SiC/ZnO nano heterojunction can obtain higher current and improve the piezoresistive performance.

Preferably, the SiC nanowire has the diameter of 200-900nm and the length of 5-30 μm.

Preferably, the thickness of the ZnO nano layer is 10-30 nm. The ZnO nano layer covered on the surface of the SiC nanowire utilizes the synergistic effect of the two materials, which is beneficial to improving the piezoresistive coefficient of the SiC/ZnO nano heterojunction, the thickness of the ZnO nano layer covered on the surface of the SiC nanowire is very important to select, and the synergistic effect of the ZnO nano layer and the ZnO nano layer can not be played by any covering thickness of the ZnO nano layer. When the thickness of the ZnO nano-layer is within the range of 10-30nm, the piezoresistive coefficient of the SiC/ZnO nano-heterojunction is superior to that of a single SiC nanowire, and when the thickness of the ZnO nano-layer is beyond the range, the piezoresistive coefficient of the SiC/ZnO nano-heterojunction is inferior to that of the SiC nanowire.

More preferably, the thickness of the ZnO nano layer is 18-22 nm. The ZnO nano-layer within the thickness range enables the SiC/ZnO nano-heterojunction to have better piezoresistive effect.

One of the objects of the present invention can be achieved by the following technical solutions:

the preparation method of the SiC/ZnO nano heterojunction pressure sensor comprises the following steps:

(1) preparing a SiC/ZnO nano heterojunction:

dispersing the SiC nanowires in an ethanol solution, dripping the ethanol solution containing the SiC nanowires on a Si wafer, and naturally airing;

then putting the Si sheet carrying the SiC nanowire with the upward surface into an atomic layer deposition system, and growing a ZnO nano layer on the surface of the SiC nanowire by taking diethyl zinc and water as precursors for growing the ZnO nano layer in an inert atmosphere, thereby obtaining the SiC/ZnO nano heterojunction;

(2) constructing a pressure sensor:

and (3) constructing the Pt/Ir-SiC/ZnO-Si pressure sensor by using the Si sheet carrying the SiC/ZnO nano heterojunction in an atomic force microscope conduction mode.

The SiC nanowire for constructing the SiC/ZnO nano heterojunction can be selected from one or more of the following: one or more of undoped SiC nanowires, N-doped SiC nanowires, and P-doped SiC nanowires.

Preferably, the SiC nanowire is an N-doped SiC nanowire, and the synergistic effect generated between the N-doped SiC nanowire and the ZnO nano layer is superior to that generated between the undoped SiC nanowire and the ZnO nano layer.

Preferably, the doping amount of N in the N-doped SiC nanowire is 1-3 at%.

Preferably, the preparation method of the N-doped SiC nanowire comprises the following steps:

heat crosslinking curing and crushing polysilazane, and then putting the polysilazane into a graphite crucible;

placing a carbon fiber cloth substrate loaded with a catalyst on the top of a graphite crucible;

and placing the graphite crucible in an atmosphere sintering furnace, vacuumizing the atmosphere sintering furnace to 1-5Pa, introducing protective atmosphere, and sintering under the protective atmosphere to obtain the N-doped SiC nanowire.

The steps of the polysilazane thermal crosslinking curing and crushing are as follows: the raw material polysilazane is at N₂Or the heat crosslinking solidification is carried out under the protection of Ar atmosphere and the temperature of 250-300 ℃ for 20-40min, and the solid obtained by solidification is ground into powder by ball milling.

The carbon fiber cloth substrate supported catalyst is preferably selected from one or more of the following: cobalt nitrate, nickel nitrate, ferric nitrate and nickel sulfate.

Further preferably, the catalyst is cobalt nitrate. Soaking the carbon fiber cloth substrate in 0.02-0.08mol/L Co (NO)₃)₂Adding ethanol solution, and air drying to obtain Co (NO) loaded₃)₂The carbon fiber cloth substrate of (1).

In the method for preparing the N-doped SiC nanowire, the volume ratio of N is adopted₂Ar is (2-6) and (94-98). The temperature is rapidly raised from room temperature to 1400 ℃ and 1500 ℃ at the rate of 20-30 ℃/min, and then the temperature is continuously raised to 1550-1 ℃ at the rate of 3-7 ℃/minAnd (3) cooling at the temperature of 600 ℃, then cooling at the cooling rate of 15-25 ℃/min, and finally cooling the furnace to room temperature to obtain the N-doped SiC nanowire.

Preparing a SiC/ZnO nano heterojunction: the N-doped SiC nanowires grow on the carbon fiber cloth substrate, when the SiC/ZnO nano heterojunction is prepared, the prepared N-doped SiC nanowires are scraped from the carbon fiber cloth substrate and dispersed into absolute ethyl alcohol, and the absolute ethyl alcohol is subjected to ultrasonic treatment by an ultrasonic disperser for 5min to be uniformly dispersed. And (3) dripping ethanol solution containing the SiC nanowires on the Si substrate, and naturally airing at room temperature. And then putting the Si sheet carrying the SiC nanowire with the surface facing upwards into an atomic layer deposition system, and growing a ZnO nano layer on the surface of the SiC nanowire by taking diethyl zinc (DEZn) and water as precursors for growing the ZnO nano layer in an inert atmosphere, thereby obtaining the SiC/ZnO nano heterojunction.

Preferably, the inert atmosphere is nitrogen or argon.

Preferably, the deposition temperature of the atomic layer deposition system is 150-200 ℃.

Preferably, the rate of growing the ZnO nano-layer on the surface of the SiC nano-wire is 0.10-0.20 nm/cycle.

The following steps constitute a cycle: introducing gas-phase diethyl zinc for 0.01-0.05s, performing chemical adsorption on the surface of the SiC nanowire, waiting for inert atmosphere purging for 20-30s, introducing water vapor for 0.005-0.15s, reacting with the surface diethyl zinc to generate ZnO, and waiting for inert atmosphere purging for 20-30s, thereby completing a growth cycle.

The thickness of the ZnO nano-layer is preferably 10-30nm, and the number of cycles is selected according to the required thickness.

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the invention, the ZnO nano layer is deposited on the surface of the SiC nanowire by an atomic layer deposition method, the ZnO nano layer which is uniformly distributed can be obtained, and the thickness of the obtained ZnO nano layer of the SiC/ZnO nano heterojunction is controllable;

(2) the SiC/ZnO nano heterojunction is used as a functional unit of the pressure sensor, the whole measurement result reaches the nN and pA levels, and high-sensitivity detection can be realized;

(3) the SiC/ZnO nano heterogeneous structure with the ZnO nano layer of which the thickness is 10-30nm is adopted as the functional unit of the pressure sensor, the piezoresistive coefficient of the SiC/ZnO nano heterogeneous structure is obviously higher than that of a single N-doped SiC nanowire, and the prepared pressure sensor has higher sensitivity.

Drawings

FIGS. 1(a) and (b) are Scanning Electron Microscope (SEM) images of SiC/ZnO nano-heterojunction fabricated in example 1 of the present invention;

FIG. 2(a) is a Transmission Electron Microscope (TEM) image, FIG. 2(b) is a High Resolution Transmission Electron Microscope (HRTEM) image, FIG. 2(c) is a Selected Area Electron Diffraction (SAED) image, and FIG. 2(d) is an EDS energy spectrum of the SiC/ZnO nano heterojunction prepared in example 1 of the present invention;

FIGS. 3(a) and (b) are X-ray diffraction (XRD) patterns of SiC/ZnO nano-heterojunction prepared in example 1 of the present invention;

FIG. 4 is a schematic structural diagram of a pressure sensor constructed by a SiC/ZnO nano heterojunction manufactured in embodiment 1 of the present invention;

FIG. 5 is a current-voltage (I-V) curve diagram of the SiC/ZnO nano heterojunction pressure sensor prepared in example 1 of the present invention under different pressures;

FIG. 6 is a graph showing the resistance change of the SiC/ZnO nano heterojunction pressure sensor manufactured in example 1 of the present invention under different pressures;

FIG. 7 is a graph showing the piezoresistive coefficient variation of the SiC/ZnO nano heterojunction pressure sensor manufactured in example 1 of the present invention under different pressures.

FIG. 8 is a Transmission Electron Microscope (TEM) image of a SiC/ZnO (10nm) nano-heterojunction obtained in example 2 of the present invention;

FIG. 9 is a graph showing piezoresistive coefficient variation curves of a SiC/ZnO (10nm) nano heterojunction pressure sensor manufactured in example 2 of the present invention under different pressures;

FIG. 10 is a Transmission Electron Microscope (TEM) image of a SiC/ZnO (30nm) nano-heterojunction obtained in example 3 of the present invention;

FIG. 11 is a graph showing piezoresistive coefficient variation curves of a SiC/ZnO (30nm) nano heterojunction pressure sensor manufactured in example 3 of the present invention under different pressures;

FIG. 12 is an SEM representation of N-doped SiC nanowires prepared in comparative example 1 of the present invention;

fig. 13(a) is a Transmission Electron Microscope (TEM) image, fig. 13(b) is a High Resolution TEM (HRTEM) image, fig. 13(C) is a Selected Area Electron Diffraction (SAED) image, fig. 13(d) is an EDS energy spectrum, fig. 13(e) is a combined image of the surface distributions of three elements of Si, C, and N of the N-doped SiC nanowire, fig. 13(f) is a surface distribution image of the element C, fig. 13(g) is a surface distribution image of the element Si, and fig. 13(h) is a surface distribution image of the element N of the N-doped SiC nanowire manufactured in comparative example 1 of the present invention;

FIGS. 14(a) and (b) are X-ray diffraction (XRD) patterns of N-doped SiC nanowires prepared in comparative example 1 of the present invention;

FIG. 15 is a current-voltage (I-V) curve diagram of the pressure sensor of the present invention prepared in comparative example 1 under different pressures;

FIG. 16 is a graph showing the resistance change curves of the pressure sensor made in comparative example 1 under different pressures;

FIG. 17 is a graph showing the piezoresistive coefficient variation of the pressure sensor made by the present invention in comparative example 1 under different pressures.

Detailed Description

The technical solution of the present invention will be further described and illustrated by the following specific embodiments in conjunction with the accompanying drawings. The raw materials used in the examples of the present invention are those commonly used in the art, and the methods used in the examples are those conventional in the art, unless otherwise specified.