| The in-situ (etching solution) development of porous silicon (PS) photoluminescence (PL) in several etch solution environments as well as the controlled modification of these environments has been studied. For certain select environments, the net effect of these in-situ treatments on ex-situ behavior was considered; The modification of the PS surface appears to facilitate the formation of a photoluminescing “blue-green” precursor state as well as a “deep red” emitter, both of which appear to be associated, at least in part, with surface bound silylene isomers. The importance of these results to sensor development is also considered.; The development of a sensitive porous silicon (PS) gas sensor, which utilizes electroless metallization as a means to obtaining a highly efficient electrical contact has been demonstrated for the detection of HCl, NH 3, and NO at the 10 ppm level. The problem of spreading resistance (kΩ-MΩ) normally associated with PS is overcome as low surface and contact resistance contacts ∼40 Ω are made to the mesoporous PS surface structure through electroless gold plating. The resulting sensor response is rapid and sensitive, and the device has an extremely rapid recovery time. It might be easily integrated into an electronic measurement system. |
