Steady-state photoconductivity in amorphous germanium selenide films

Steady-state photoconductivity measurements are carried out on GexSe100-x s emiconductors, where 20 less than or equal to x less than or equal to 50, i n the temperature between 290 and 470 K. The conductivity parameters vary w ith composition and exhibit extrema near the chemical threshold composition . at coordination number <r > = 2.67 where x = 33%. The temperature and lig ht intensity dependence of the photoconductivity ensure the presence of mon o- and bimolecular recombination regions. The measured activation energies in the two regions suggest energy levels of recombination centers in the ga p at 0.66 and about 1.37 eV from the top of the valence band. (C) 2001 Else vier Science B.V. All rights reserved.