Steady-state photoconductivity in amorphous germanium selenide films

Steady-state photoconductivity measurements are carried out on Ge_xSe_100-x semiconductors, where 20≤x≤50, in the temperature between 290 and 470 K. The conductivity parameters vary with composition and exhibit extrema near the chemical threshold composition, at coordination number 〈r〉=2.67 where x=33%. The temperature and light intensity dependence of the photoconductivity ensure the presence of mono- and bimolecular recombination regions. The measured activation energies in the two regions suggest energy levels of recombination centers in the gap at 0.66 and about 1.37 eV from the top of the valence band.