In amorphous semiconductors, macroscopic properties are dominated by localized states. Photomodulated IR spectroscopy is a valuable tool for the study of localized states of this amorphous semiconductor. We have measured the photoinduced IR absorption of a-Si1-xCx:H. The observed spectra are quantitatively accounted for by a model, which allows one to determine the width of the conduction and valence band tail states separately. p-type a-Si1-xCx:H can be made microporous by anodisation in HF electrolyte. It luminesces at energies much higher than the bulk material. Infrared characterisation of the porous layers suggests that carbon concentration is higher in porous a-Si1-xCx:H than in the starting material, accounting for the luminescence blue shift. This carbon enrichment, due to selective Si dissolution during porous formation, has been confirmed and quantified by SIMS. We have measured the photoluminescence of a-Si1-xCx:H between 77 and 400K. Using the results of our previous photomodulated IR absorption study, we propose a more complete discussion of temperature dependent PL, presenting a model which fits experiment quantitatively.
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