부산대학교 도서관

The d.c. photoconductivity σph and the photoluminescence intensity Ipl of a-Si:H have been studied concomitantly as a function of temperature (10-100 K) and electric fields (up to 2 × 105 V cm-1). The defect density Nd, was varied by electron bombardment and subsequent annealing in the range 3 × 1015-5 × 1017 cm-3. The results cannot be explained in a geminate-pair model. The general behaviour suggests that the strongly superohmic I-V characteristics are not caused by the field-dependent generation of free carriers but by a field dependence of the transport itself. It is argued that the photocurrent arises predominantly from carrier displacement during the thermalization by hopping in the band-tail states.