Study On Gas Sensing Properties Of Porous Silicon

Porous silicon material has many characteristics, such as a simple preparation, low cost, easy integration, low environmental pollution and so on, which can be used to detect various types of oxidizing gases (such as NO2) and reducing gases (such as CO). It is one of the hottest research sensitive material now. Uniformity of the porous silicon surface of the silicon arrangement is the main way to improve the sensitivity of porous silicon material. We analyze the surface morphology of porous silicon which made by preparation of dual chamber electrochemical method in this article. We research the influence of the porous silicon layer on ethanol gas sensing properties of gas and briefly analyze its sensing mechanism. The following results are obtained:1. Nanoscale pore size of the porous silicon layer successfully prepared by using self-made double cell electrochemical etching. Results show that the porosity of porous silicon made on 1-10Ω · cm high resistivity and 0.001-0.0016Ω · cm low resi-stivity silicon increase first and then decreases features with increasing current density. When the current density is 40mA/cm2, the porosity is maximum. The poro-sity of the porous silicon prepared on 0.01-0.02Ω · cm resistivity silicon wafer with increasing current density increases.2. We analysis surface morphology of three groups of porous silicon.Results show that porous silicon made on resistivity 0.01-0.02Ω· cm wafers show best uniformities in there groups, which are the smallest the aperture, the deepest hole. At 40mA/cm2, the surface morphology is the best.3. We study the gas-sensing properties of porous silicon layers made on resistivity 0.01-0.02Ω · cm wafers with different concentrations of ethanol. Results show that better surface uniformity means better gas sensing performance.less surface uniformi-ty means less gas sensing performance. In 40mA/cm2, the gas sensitivity of different concentration ethanol was relatively stable, the average value reached to 2.24.