Optical modulation spectroscopy of hydrogenated microcrystalline silicon

[摘要] The properties of microcrystalline silicon thin films prepared by r.f. sputtering were investigated by optical modulation spectroscopy (OMS) at room temperature and the results were correlated with Raman and conductivity measurements. For comparative purposes, a number of good quality PECVD mu c-Si:H samples were also investigated. For PECVD samples the OMS signal is very weak, and only measurable for probe beam energies comparable with the gap of amorphous silicon. This indicates the absence of gap states and therefore a very high crystalline fraction, as confirmed by Raman and TEM measurements. For r.f.-sputtered samples, different behaviours can be distinguished. Some samples show a low OMS signal which can be attributed either to a high crystallinity (low density of gap states) or to high recombination rates. These two cases can be distinguished by electrical conductivity values and analysis of the Raman spectra. Other samples exhibit an OMS signal similar to a-Si:H and have low conductivity values, consistent with a Raman spectrum typical of a-Si:W. (C) 1997 Elsevier Science S.A.

[发布日期] 1997-03-01

[效力级别]  Proceedings Paper

[关键词] optical modulation spectroscopy;hydrogenated silicon