Sensing Properties Of Nanocrystal Tin Oxide/Silicon Nanoporous Pillar Array

With the development of science and technology and the improvement of life quality, sensors used to detect environment development toward the direction of miniaturization, integration and intelligent.Tin oxide (SnO2) is the star of the traditional semiconductor gas sensor materials, it have very good sensing properties under atmosphere such as methane, hydrogen sulfide, carbonic oxide, ethanol, etc. But the research on sensitive performances of tin oxide toward different relative humidity were not very fully. As silicon nanoporous pillar array (Si-NPA) own unique structure known as a nano/microns triple levels, while it is used as a substrate, it can not only provide larger gas contact surface area for sensing element, but also provide effective channels for vapor transmission, thus effectively improve the response performance of sensing material.In this paper, aims at preparing sensing nanocomposite with high surface area and uniform particle, SnO2 thin film was deposited with nanometer size onto the Si-NPA substrate by chemical vapor deposition (CVD) method, then SnO2/Si-NPA nanocomposite system were obtained. We researched its humidity performance and gas sensitivity. According to this subject, some experimental work have been carried out and results are as follows:1. With the help of X-ray diffractometer (XRD), scanning electron microscope (SEM), we studied how the controllable growth conditions influence on the morphology structure of composite films, such as the reactants quality, reaction source location, growth temperature, growth time and ventilation time, and so on. Then we can obtained good quality SnO2/Si-NPA nanocomposite system.2. In a series of different humidity conditions, the SnO2/Si-NPA relative humidity(RH)- sensitive were measured. According to the characteristic of capacitance-RH and sensitivity-humidity response under different test frequencies, we find the best test frequency is 1000Hz. Test results show that SnO2/Si-NPA humidity sensitive component has strong signal output, excellent linearity, high sensitivity, repeatability, etc. SnO2/Si-NPA device's response to water is the product of joint action of the SnO2 and the Si-NPA substrate.3. The SnO2/Si-NPA gas sensitive were researched in one closed installation which can control the gas concentrations, velocity, and reaction temperature. According to theⅠ-Ⅴcharacteristic curves under different concentration conditions, we explored the SnO2/Si-NPA sensor's performance for different H2S, CO concentrations under certain temperature.