Invetigation Of Porous Silicon-based Functional Films

The porous silicon (PS) fabricated using the method of electrochemical etching, is a good functional film material, due to its wide controllability on its layers thickness and porousity which is related with with its refrective index. For instance, the PS can be used as the carrier for multiple deposition and absorption materials because it possesses large surface area.In this thesis, we first studied the properties of the PS and PS microcavity. Based on the electromagnetic theory of light, we deduced the transfer matrix of light in PS and edited a LabVIEW program for calculating the reflective light spectrum of PS multilayer. In experiment, we successfully fabricated the silicon-based wide band thin black silicon. The electrochemical etching of single crystal silicon was controlled by the computer during the process and the PS anti-refrective layer called black silicon was obtained with its porousity ontinuously changed with etching depth. The refrectance of the black silicon sample was less than 5% over a broad wave band and its thickness is below 1μm. We also carried out the theoretical simulation on the reflective spectrum of black silicon sample using the transfer matrix method. The simulation results gave a good agreement with the experimental measurements.Secondly, we investigated the effects of organic adsorbent on the photoluminescence of porous silicon microcavities. The effects of organic absorbent on the refractive index and photoluminescence of porous silicon microcavities were theoretically investigated by using the Bruggeman effective medium approximation. Experimentally, porous silicon microcavities were fabricated by computer controlled electrochemical etching, and then interacted with the molecules of oil vapor from a rotary pump. We found that the narrow photoluminescence spectra of porous silicon microcavities were sensitive to the adsorption and de-adsorption of the oil vapor molecules, which leading to a 71 nm red-shift and the intensity variation in photoluminescence spectrum. The experimental results qualitatively consist with our theoretical estimation.