Research Of Nanoporous Silicon Photonic Devices

Porous silicon thin film is a spongy porous material with large specific surface area. Inthe past years, porous silicon has received intensive attention as a sensor material because ofits advantages of low cost, good biological compatibility and fully compatibility for today'sintegrated circuit technology since the1990s. In this dissertation, the optimization oftechnique to prepare porous silicon is achieved and the optical biosensor devices are designedbased on SOI porous silicon. At the same time, we studied the fabrication technique, structurecharacterization and photoluminescence (PL) properties of porous silicon composite materials.The main conclusions in this thesis are as follows:1. Improvement of the technique for the preparation of porous silicon: we have studiedthe effectiveness of the concentration of conductive liquid for the morphology of poroussilicon. It is found that, with an appropriate conductive liquid concentration and keeping theother etching parameters unchanged, it is easier to get the desired porous silicon in doubletank electrochemical etching process. The technique of the traditional double tankelectrochemical etching cell is improved and we have prepared multilayer porous silicon oninsulator silicon silicon-on-insulator (SOI) by the electrochemical method.2. ZnS/ZnO/PS compounds were prepared by chemical vapor deposition (CVD) method.The morphology structure and photoluminescence characteristics of the samples weremeasured. The results show that ZnS/ZnO/PS composite system presents a strong green lightemission. Combined with the energy dispersion spectroscopy (EDS), X-ray diffraction (XRD)and scanning electron microscopy (SEM), reunion phenomenon was found in theZnS/ZnO/PS complex. We attributed these properties to the deep defects of ZnO and defectcenters of ZnS. New conjugated polymer (9,9-diocty-2,7-fluorene-co-4,4'-butoxydiphenyl)(PFP) film was coated onto the surface of PS by spin-coated method. The PL and I-Vcharacters were measured and the results show that PFP/PS composite has the intensive blue PL. Based on the I-V characteristics, PFTQ/PS shows the unsaturated reverse rectifyingjunction behavior. We also studied the structural and optical properties of a-Al2O3film grownon porous silicon substrate using sol-gel method. From the photoluminescence spectrum, itshows a narrow purple emission peak. This proved that porous silicon is a good substrate togrow a-Al₂O₃film.3. Raman signal analysis for porous silicon: the effects of oxidation on Raman spectra ofporous silicon were investigated using Raman spectroscopy analysis method. Many Si-Hxbonds were found in as-anodized porous silicon. It was found that the intensity of Ramanscattering become weak and some silicon hydrogen bonding characteristic peaks aredisappeared which are attributed to the changes of crystalline silicon particle size and a silicacoated layer on porous silicon pore wall. High-temperature oxidation is superior to thehydrogen peroxide oxidation for its thorough oxidation.4. An optical immunoassay was developed by the optical reflectance spectroscopy of theSOI porous silicon with single layer and multi-layer SOI porous silicon (Bragg mirrors andoptical cavity). The probe molecules were immobilized to the PS using silanization andglutaraldehyde chemistry. The sensitivity and the lowest detection limit were calculated by theexperimental slope. This research played a potential role for the extensive applications inall-silicon biosensor.