Porous Silicon Nanowire And Its Gassensing Properties

The rapid development of industrialization associated with a large number of toxic and harmful gases so that the natural environment of human survival has been severely damaged,the development of high-performance gas sensor has an urgent practical significance.Silicon nanowires with one-dimensional characteristics are potential room-temperature gas-sensing materials and have very good application prospects in high performance and low power consumption integrated gas sensor.In this paper,one-step and two-step metal-assisted chemical etching was used to etch highly doped monocrystalline silicon substrate in hydrofluoric acid,silver nitrate and hydrogen peroxide solution to fabricate one-dimensional silicon nanowire arrays.The microstructure of porous silicon nanowires was characterized by SEM,TEM and EDS were used to characterize the microstructure of porous silicon nanowires.The etching time,the concentration of hydrogen peroxide and the concentration of silver nitrate on the morphology of porous silicon nanowires were studied.The gas sensing properties of porous Si nanowires were evaluated by using gas testing platform.It was found that the length of the porous silicon nanowires get longer with the increase of the etching time and the concentration of hydrogen peroxide.With the increase of the concentration of silver nitrate,the length of the porous silicon nanowires increased first and then decreased.Porous silicon nanowires are able to detect ppb levels of nitrogen dioxide gas,and has a very rapid response characteristics.The porous silicon nanowires prepared by the one-step etching method have a good response recovery characteristic but a low sensitivity while the concentration of the nitrogen dioxide gas is 0.05-4 ppm.By controlling the concentration of hydrogen peroxide and the concentration of silver nitrate is constrained to obtain a gas sensor with excellent performance.The porous silicon nanowires measure the concentration of nitrogen dioxide in 0.25-1.5 ppm.When the concentration of nitrogen dioxide is 1.5 ppm,the measured response time is 2seconds,The recovery time was 145 s,and the sensitivity was 124.