Wet-Chemical Preparation And Properties Of Several Types Of Thin Film

In this thesis, the author focuses on the preparation and properties of severaltypes of functional thin film materials by wet chemical methods. These thin filmsinclude chalcopyrite thin-film solar cell absorb layer by electrochemical depositionand chemical bath deposition, silicon nanowire thin-film by metal-induced chemicaletching, and surface-enhanced Raman scattering (SERS) substrates by displacementreaction deposition.Chalcopyrite semiconductor thin films have been intensively investigated since1980s. It is considered to be one of the most promise thin film solar cell materials.The author has prepared CuInSe₂(CISe) and CuInS₂(CIS) precursor films byone-step electrochemical deposition and one-step chemical bath depositionmethods, respectively. The vacuum annealing post-treatment process has beenadopted to prepare chalcopyrite structure instead of using harmful Se or S atmosphere.In order to simplify the structure of CISe thin film solar cell and obtain Cd-free solarcell materials, the author has prepared quasi-homojunction on p-type CISe thin filmby the process of Zn diffusion.One-dimensional nanomaterials have attracted much attention because of theirunique structures, and electrical, optical, mechanical properties. The author hasprepared porous silicon nanowires on the single-crystal silicon and multicrystallinesilicon substrates by metal-assisted chemical etching method. The author investigatedthe effect of the H₂O₂concentration, etching time, and surface passivation on thestructures, surface chemical states, and photoluminescent properties. The lightemitting mechanism of the nanostructure films and the formation mechanismof porous silicon nanowires have also been discussed. The combination ofsilicon nanowire structure and porous silicon structure with light-emittingproperties may open new opportunities for nanoscale optoelectronic devices,photoelectrochemical devices, solar cell, and sensors, etc.Three-dimensional SERS-active substrates have received significant attentiondue to their strong enhancement factor and good reproducibility. The author has prepared silver nanoparticle films on the silicon nanowire arrays andsilver dentrites on copper substrate by the single-displacement reactionbetween Ag⁺cation and Si (Cu). The enhancement factors for rhodamine6G(R6G) on the silver-coated silicon nanowire film and the silver dendrites filmsubstrates can be1.410⁵and2.910⁷, respectively. Our results can be ofespecial importance for the quantitative detection of trace amount analyticalspecies and standardization of SERS substrates.