高多孔度多孔硅的发光性能与表面修饰研究

Porous silicon (PS) has been the focus of extensive research in the past decade, due to its potential applications in silicon-based optoelectronic, planar displayer and sensing devices. In this project, detail experimental studies have been on the preparation and the optical properties of free-standing PS films with high porosities, the photoluminescence (PL) property of the PS controled by surface compositions, and surface modification of the PS by chemical synthetic strategies. The main progresses are listed as follows:1.We have prepared non-collapsed free-standing PS films with various porosities even higher than 90% using the anodization-electropolishing, chemical dissolving and supercritical drying method. Furthermore, the evolution of the structure and the optical properties of these PS films during thermal oxidation at 200°C.2.Hydrocarbn has been attached to the surface of the freshly pepared PS through the association reaction between the Si-H species on the surface and the unsaturated hydrocarbons. An intense blue-violet band, centered at 3.0 eV, has been observed from the chemically modified PS by 5-cyano-1-pentyne. The decays of this blue-violet emission with a lifetime about 0.5ms are different from the nanosecond lifetimes of the blue emissions in the oxidized PS samples reported before..3.A novel catalytic reaction using a trace of organic amine as the catalyst enables hydrolysis of the silicon-hydrogen groups on the fresh prepared porous silicon (PS), generating the hydroxyl-terminated surfaces without extensive oxidization of the Si-Si backbonds. The reactivity of the hydroxyl-terminated surfaces with various silanization reagents was investigated, which proceeds by abstraction of the surface-OH to form an organic monolayer of Si-O-Si-C bonds and importantly retains the intrinsic structural properties of the PS layers. Furthermore, an in situ silanization modification of the silicon-hydrogen surfaces has been established. Stability testing shows that the resulting organic monolayers are densely packed and are shown to be highly stable under a variety of conditions including hot water, hot organic solvent, acid, and base, but can be removed by a HF rinse.4.Studies on liquid growth and shape control of crystal silicon nanostructures have been carried out. It is found that PS films can dissolve in PCl5 solution, and then, silicon nanostructures, such as nanowires, nanowalls, cubic, and triangle, were grown from this solution. To our knowledge, there is no report on liquid growth of silicon nanowires at low temperature. Nanowalls, cubic, and triangles of silicon are the first observed.

本项目展开展多孔硅的发光性能与表面修饰研究。在制备高多孔度多孔硅及自支撑膜的基础上，大范围地改变多孔硅的微结构，直接关联光吸收、光发射、载流子传输性能与微结构，以揭示纳米硅单元与多孔硅发光的关系。另外，利用高度孔度多孔硅的高比表面，通过化学键合功能分子修饰多孔硅表面，借以改变表面层结构，探索改善发光性能的途径。