Compositional variations of porous silicon layers prior to and during ionhyphen;beam analyses

摘要

The suitability of ionhyphen;beamhyphen;analysis techniques in quantifying the composition of mesoporous silicon nanostructures has been critically examined using films of moderate porosity (55percnt;) prepared onn+substrates. The effects of roomhyphen;temperature aging of ashyphen;etched and thermally oxidized porous silicon, the oxidation conditions chosen to render the material luminescent, have been carefully monitored, as have the effects of both ionhyphen;beam irradiation and storage of samplesinvacuo. It is shown that the concentrations of the three major impurities oxygen, carbon, and hydrogen can be appreciably altered during analyses, thereby limiting the reliability of the techniques, as conventionally applied to porous silicon. The use of appropriate capping layers, which should alleviate the problem, is recommended.