M. Zelikson et al., STUDY OF SUB-BANDGAP PHOTOINDUCED ABSORPTION IN A-SI-H USING EXCITATION SPECTROSCOPY IN A WAVE-GUIDE CONFIGURATION, Journal of non-crystalline solids, 200, 1996, pp. 259-262
The photo-induced absorption of lambda=1.3 mu m light in an a-Si:H bas
ed waveguide is studied by means of excitation spectroscopy. At very h
igh levels of the pump intensity the probe beam absorption tends to sa
turate. This phenomenon is related to high order recombination mechani
sms. It is shown that the interface absorption makes a significant con
tribution to the absorption process. The experiments reveal the existe
nce of localized interface states with energies which lie close to the
mobility edges of a-Si:H and which are slightly different for the two
interfaces.