The Research On New Fabrication Method, Luminescent Property And Mechanism Of Porous Silicon Materials

As a silicon-based material with light-emitting function, porous silicon hasbeen widely researched by scientists all of the world and becomes a represent ofsilicon-based nanometer materials because of its merits, such as easy integratingwith silicon chips, low cost, several colors light emitting etc..In this research, porous silicon was obtained by chemical-electrochemicaletching ("two-step method" for short) and "laser method" and itsphotoluminescence properties, surface and cross-section morphology, elementalcomposition, surface bond structure, phase structure were measured andanalyzed.Porous silicon prepared by "two-step method" can emit stronger and stablervisible light compared to porous silicon prepared by electrochemical anodization.There is also a blue shift in two-step porous silicon. Testing results proved thatthe light emission with higher intensity and stability is due to the formation ofSi-Ag bonds. In addition, two-step porous silicon may overcome the difficulty ofefficient electrical contact because of it novel structure which porous siliconlayers prop up some silicon wires. This structure may stimulate the design on thenext generation of silicon-based light emitting devices. While "porous siliconwires" can emit stronger light because it contains much porous silicon, thereforeit can be used to prepare devices with better light-emission properties.On the other hand, porous silicon with silica gel can emit blue light afterirradiated by laser with given power density. Once the blue-light emission wasobtained, it will not change with the increase of the power density of laser.Analysis results show that it is not crystal-to-amorphous transformation but theformation of Si-C bonds and Si-C-O bonds which causes the blue-light emission.