Influence Of Doping On Optical Properties Of Porous Silicon And ZnO Films

Silicon is most widely used in the study of micro-electronic materials, but because silicon is an indirect band gap semiconductor, a narrow band gap, low luminescence efficiency, and thus restricting its application in the field of optoelectronics. In 1990, British scientists Canham first observed that porous silicon can exhibit visible photoluminescence at room temperature and explain with the quantum confinement effect, in order to achieve specified in the prospects for silicon-based optoelectronics integration, so that porous silicon quickly became the hot topic around the world. In 1996,it has generated more interest after photoelectron integrate circuit which porous silicon was the basic material. It is also provided impossible of whole silicon photoelectron integrate. Extensive efforts have been made till today to achieve more stable light emission which have wider spectrum. Many researchers have improved the character of porous silicon's photoluminescence by those methods: metal-aided electrochemical etching, oxidation by wet treatment, photochemical etching and so on.The paper first briefly introduced the development of porous silicon and its composite structure, as well as preparation of research applications. It mainly describes the different ways the technology of preparation of porous silicon and porous silicon micro-structure and chemical composition of the research findings. On this basis, this article summarizes the key mechanism for the formation of porous silicon and the light-emitting mechanism. The formation of porous silicon from the mechanism of the light-emitting mechanism of porous silicon and optical properties were discussed. Even though the current system of porous silicon light-emitting mechanism of a number of theoretical models, but are split on their views and did not reach a consensus. Therefore, light-emitting mechanism of porous silicon and the formation mechanism of the research, as well as how to produce superior performance to meet the laser requirements OEIC more effort required.Doping silicon with rare earth is one of the approaches on investigation of the silicon-based materials with high luminescent efficiency. Porous silicon has shown to be a promising host of rare earth because of large surface. The rare earth element yttrium(Y) was doped in porous silicon with electrochemical method. The photoluminescence (PL) properties of the samples were studied with fluorescence spectrophotometer. Under excitation by laser with wavelength of 440nm, porous silicon has its photoluminescence peak located at 620nm, which is considered come from luminescence center of Si-O complex; under excitation by laser with wavelength of 390nm, porous silicon has photoluminescence peak located at 527nm and 576nm, with an explanation by QCLC model. Photoluminescence of yttrium-doped porous silicon get an obvious enhancement, with a new peak located around 484nm. Analysis reveals that this is resulted from doping of yttrium, which forms new surface energy levels in band gap of porous silicon, consequently forms new luminescence centers.In addition, different amount of Ag-doped ZnO thin film were prepared on quartz substrate by sol - gel method, effect of the Ag doping on structure and optical characteristics of the ZnO thin film were studied by X-ray diffraction and UV spectrophotometer. Found that, with the increase in the number of Ag-doped, zinc oxide (002) diffraction peaks move to small-angle, intensity gradually become smaller, and increased FWHM, at the same time band gap became smaller, analysts believe that this is as a result of Ag²⁺ ions substitute for Zn²⁺ ions, leading to a clear expansion of cell volume results. In 1% Ag-doped of the zinc oxide film on the UV transmittance of the minimum, and the absorption edge of doped zinc oxide thin films shifted to longer wavelengths. Proving through experiments, Ag-doped can effective to adjust the structure of ZnO thin film, and change optical properties of zinc oxide thin film...