Research Of NO₂ Semiconductor Sensor Based On ZnSe And Their Heterojunction

NO₂ is becoming one of the harmful gas that bothered humans recently.Excessive NO₂ is an important cause of acid rain,acidification of surface water and eutrophication.Semiconductor gas sensor is one of the important means to detect the concentration of NO₂ in the atmosphere which is favored by researchers.The core of semiconductor gas sensor is the semiconductor material to make the sensor.For ZnSe,as one of the very important semiconductor material which belongs to the wide direct band gap II-VI group.It has excellent photoelectrocatalysis and photoelectric conversion activity in the visible range.It can be used to make blue light-emitting devices,infrared thermal imager,all-weather optical device and solar cells.It has a broad prospect in the fields like communication,copy,high-density information storage,high resolution image display,signal indication,biomedical science and basic research and etc.At present a lot of research dedicated to the study of ZnSe photocatalytic performance,but because of ZnSe and ZnO crystallites with crystal structure,and belong to the same?-?clan and wide bandgap semiconductor material,and ZnO after a lot of research in the field of a variety of gas detection to meet the testing index,and the ZnSe research also is not very perfect,so the gas-sensing properties of ZnSe research is very necessary.In this paper,ZnSe is used to compound with other semiconductor materials?mainly NiO?to form heterogeneous structures as sensitive electrode materials for the study of NO₂ sensor.Main contents are as follows:?1?The nanometer flake and block structure of ZnSe were prepared by hydrothermal method with advantages of simple preparation process,low cost and little pollution.The crystal structure and morphology of the nanomaterials were characterized by SEM,TEM?XPS and XRD.?2?Design and preparation of heterojunction semiconductor nanomaterials composed of ZnSe and NiO,Based on existing ZnSe flaky nano structures,using the way of different molar ratio liquid phase reaction and subsequent heat treatment,prepared ZnSe/NiO composite structure,corresponding mole fatio of 1:1.1:2,2:1 respectively,2 each,a total of 6 samples.Characterize prepared samples with SEM,TEM,XPSand XRD.?3?The dynamic gas sensing test system was used in the laboratory.The test results showed that the sensor based on ZnSe/NiO heterogeneous structure not only had good sensitivity to NO₂ gas at8ppm concentration at 140?,but also had excellent response recovery characteristics and selectivity.?4?Based on the previous work,the analysis of flake nanostructures based on ZnSe p-type semiconductor gas sensitive characteristic principle and in different types of composite metal oxide semiconductor material-NiO for typical p-type semiconductor formed under the condition of p-p junction has good electrical properties,mainly studied the heterojunction factors influencing the performance of gas sensitive sensor and the sensor is the cause of the oxidizing gas specific selectivity.This paper provides a new research idea for the development of gas sensitive materials that can realize high sensitivity and excellent selectivity of NO2 gas,and provides theoretical and experimental basis for the development of high-performance NO2 sensors.