Preparation And Piezotronics Application Of One-dimensional ZnO Nanoarrays

Since the discovery of the piezoelectric effect in 1880,traditional piezoelectric materials(inorganic perovskite ceramic crystals and organic polymers)have soon been widely used in electromechanical sensors,actuators,and energy converters.However,the insulating properties of these materials limit their piezoelectric polarization and the coupling between electrons.In 2006,Academician Wang Zhonglin used piezoelectric semiconductor materials to prepare a new type of piezoelectric nanogenerator for the first time,and then quickly proposed the concept of piezoelectric electronics and the corresponding theory.Piezoelectric effect is to effectively combine piezoelectric polarization with semiconductor properties,and regulate the energy band and charge transfer characteristics of the semiconductor interface through piezoelectric polarization charge.Among piezoelectric semiconductor materials,one-dimensional ZnO nanomaterials have received extensive attention in nano-generators,stress-strain sensing,and theoretical research on piezoelectric electronics due to their highly controllable size and morphology and unique functionality.In order to realize the commercialization and application of one-dimensional ZnO nanoarray materials,the correlation between the regularity of its microscopic size and the structure of piezoelectric electronic devices needs to be further explored.In this thesis,low-temperature hydrothermal epitaxial growth of one-dimensional ZnO nano-array piezoelectric semiconductor materials is used to study the influencing factors of epitaxial growth of ZnO nano-arrays,and the growth mechanism is analyzed and discussed.One-dimensional ZnO nano-arrays with excellent performance are obtained based on epitaxial growth to realize the design and preparation of high-sensitivity pressure sensors to explore the effect of piezoelectric electronics.The main content and conclusions of this article include the following parts:(1)In this thesis,a low-temperature hydrothermal synthesis method is used for homoepitaxial growth of ZnO nano-arrays,and one-dimensional ZnO nano-arrays arranged vertically are prepared.The material system for the synthesis of one-dimensional ZnO nanoarrays was optimized,and the factors affecting the homogeneous epitaxial growth of one-dimensional ZnO nanoarrays on the ZnO seed layer were focused on.The results of the study show that the zinc nitrate hexahydrate and hexamethylenetetramine system are prepared under the conditions of a precursor substance concentration of 150mmol/L,a growth temperature of 85°C,a growth time of 7h,and an added ammonia content of 5m L.A single regularly arranged one-dimensional ZnO nanoarray with a maximum aspect ratio of 78.(2)A one-dimensional ZnO nano-array homoepitaxially grown on the surface of a silicon substrate was used to assemble a 2×2 electrode pressure sensor and test the device performance.The I-V characteristic curve test of the sensor proves that the device forms a Schottky contact.Tests on the output current and voltage of a single sensor and two sensors in series and parallel have further proved that the piezoelectric effect causes the change of the Schottky barrier height.As the applied force increases,the output voltage and current increase at the same time.In the pressure range of 0.05?2.8N,the output voltage and current of the sensor have a good linear relationship with the applied force.When the force is increased to 2.8N,the maximum output voltage is about 159 m V,and the maximum output current is0.9n A.The sensitivity of the device is in the pressure range of 0.05?2.8N,which decreases with the increase of pressure.The highest resolution version is 851 m V/MPa when the applied force is 0.03 N.The sensor is tested for independence and repeatability.The test result is that the 2×2 electrode sensors are independent of each other,do not affect each other,and have good repeatability and long service life.