Optical absorption spectra in the low-energy region 0.4-1.2 eV is reported
for muc-Si:H using a photothermal deflection spectroscopy technique. Absorp
tion coefficient spectra in the low-energy region contain important informa
tion related to defects and hydrogen. It is demonstrated that there is a go
od correlation between electron spin densities and integrated absorption co
efficient spectra from 0.7 to 1.2 eV. The amount of the hydrogen molecules
in microvoids is much larger in muc-Si:H than that in a-Si:H. Light illumin
ation effects in PDS spectra has also been studied from a view point of pho
to degradation of the muc-Si:H. (C) 2001 Elsevier Science B.V. All rights r
eserved.