The Study On Optical Properties And Sensing Of One-Dimension Porous Silicon Photonic Crystal

Porous silicon is a new type functional material. In the past years, porous silicon is considered important by the sensor field because of its special pattern structure and large specific surface area. Early sensing technique mostly based on the changes of electrical parameters of porous silicon to realize detecting the gas concentration. But the electrical contact is easy to trigger explosion and fire. So for the inflammable and explosive organic vapors, sensing technique basing on the optical properties of porous silicon has more important application value.In this thesis, firstly from the physics base of the porous silicon material, the optical constant definition is given and obtains relations of those optical parameters making use of K-K relation; Porous silicon optical constant calculation principles are set forth including the theoretical and experimental methods. Finally, the optical constants spectrums are simulated.And then, the idea of photonic crystal has been introduced to the porous silicon multilayers. On the base of transfer matrix method of one-dimension photonic crystals, optical transmission properties of one dimension porous silicon photonic crystal with three typical structures have been studied. Using the way of Matlab emulation, the influences of the structure parameters the incident angles and the defective layers leading-in on the reflective characteristic of the porous silicon photonic crystals haves been discussed. So some useful conclusions are gotten which provide important theory bases in order to design porous silicon photon devices and optical sensors later.Follow, the adsorption properties of porous silicon material when exposed to the organic vapors. The capillary condensation is determined as the major adsorption mechanism according to the hysterics of the adsorption isotherm. Two possible adsorption models for the porous silicon multilayers have been presented and proved the correctness of uniform adsorption model. On this, thesingle microcavity is considered as research object, and set up the organic vapors sensing theoretical model of the porous silicon microcavities. At the same time, results are simulated by the Matlab software.At last, the experimental parameters have been orthogonal optimized. The porous silicon microcavity samples have been fabricated by applying the pulse electrochemical etching method. Then design porous silicon microcavity experimental sensing system, and some inflammable and explosive organic vapors are used as test gases. At the same time, the vapor species and the ethanol concentrations and response characteristics have been experimentally studied using the reflectance spectrum of porous silicon microcavity. From the view of experiment, it is proved that porous silicon microcavity is feasible new type optical sensor to detect the vapor species and concentration.In conclusion, porous silicon sensing technique basing on the optical properties is a non-contact measure method. It has a lot of advantages including high sensitivity, low loss, fast response, well repeatability, electromagnetic interference avoiding, safe and so on.