Ma Shuangyun

Microstructure,Electrical and Gas Sensing Properties of Meso-Porous Silicon and Macro-Porous Silicon

Two different kinds of porous silicon(PS) were grown by electrochemical corrosion in a double-tank cell on the surface of single-crystalline P-type silicon.According to their pore sizes,they were denoted as meso-porous silicon(meso-PS) and macro-porous silicon(macro-PS).The surface and cross-section morphologies of the PS were observed by scanning electron microscope(SEM).The surface chemical bonds of the meso-PS and macro-PS were investigated by Fourier transform infrared(FTIR) spectroscopy.The electrical properties of the PS were studied by measuring the I-V characteristics.The gas sensing properties of meso-PS and macro-PS were thoroughly measured at room temperature.Meso-PS has much higher sensitivity,while macro-PS has better response-recovery characteristics.Meso-PS shows better selectivity for NO2,while macro-PS shows better selectivity for NH3.

Nano-WO3 film modified macro-porous silicon (MPS) gas sensor

We prepared macro-porous silicon (MPS) by electrochemical corrosion in a double-tank cell on the surface of single-crystalline P-type silicon. Then, nano-WO3 films were deposited on MPS layers by DC facing target reactive magnetron sputtering. The morphologies of the MPS and WO3/MPS samples were investigated by using a field emission scanning electron microscope. The crystallization of WO3 and the valence of the W in the WO3/MPS sample were characterized by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The gas sensing properties of MPS and WO3/MPS gas sensors were thoroughly measured at room temperature. It can be concluded that: the WO3/MPS gas sensor shows the gas sensing properties of a P-type semiconductor gas sensor. The WO3/MPS gas sensor exhibits good recovery characteristics and repeatability to 1 ppm NO2. The addition of WO3 can enhance the sensitivity of MPS to NO2. The long-term stability of a WO3/MPS gas sensor is better than that of an MPS gas sensor. The sensitivity of the WO3/MPS gas sensor to NO2 is higher than that to NH3 and C2H5OH. The selectivity of the MPS to NO2 is modified by deposited nano-WO3 film.