Fabrication Of InAs Nanowire Arrays And Investigation Of Its Gas Sensing Properties

NO2 is one of the most dangerous air pollutants, the detection and measurement of NO2 gas is thus of great impendency. Semiconductor gas sensor is the most widely used gas sensor, because of its low cost, high sensitivity, fast response, et al. But it also exits defects that cannot be neglected. For example, the working temperature of most semiconductor gas sensors were high and the gas sensitive performance of most semiconductor gas sensor were unstable, et al. The utilization of monocrystalline heteroj unction nanomaterials to promote and optimize the performance of gas sensor is one of the present research direction.InAs is a kind of important III-V semiconductor materials with excellent characteristics, such as high carrier mobility, rich surface state and narrow band gap. Vertical InAs nanowire arrays are sensitive to NO2 concentrations well below 100 ppb at room temperature. Also, the introduce of InP shell can greatly improve the performance of InAs nanowire. InAs/InP radial hetero-j unction nanowires were widely used in photodetector and field effect transistor, et al. However, the gas sensing properties of InAs/InP radial hetero-j unction nanowires still have not been studied. In this paper, InAs/InP radial hetero-junction nanowires covered with five different InP shell thickness were fabricated by MOCVD system. The five different InP shell thickness were 0 nm,1.1 nm,3.3 nm,6.5 nm and 18 nm, respectively. The NW number customizable, gap controllable, directional arrangement of nanowires array were fabricated by using dielectrophoresis arrangement technology combined with microgroove. The dependence of NO2 sensing properties on InP shell thickness and operating temperature was investigated. For high sensitivity, the optimum operating temperature and shell thickness were 50℃ and 3.3 nm, respectively. The response speed can be increased with increasing temperature. Thus, in order to realize both high sensitivity and fast response, the compromised condition should be 3.3 nm InP shell and 90℃ operation. The sensing properties could be explained with surface accumulated electrons and H2O-aided NO2 adsorption.