The influence of antimony impurity on optical and electrical properties of amorphous selenium

Amorphous Se_1-xSb_x alloys were prepared using a conventional rapid quenching technique. It is found that antimony can only be substituted up to approximately 10 at.% in selenium to produce Se-Sb glassy alloys. The photoacoustic technique is employed for the first time to determine the optical energy gaps of Se_1-xSb_x glasses. The optical energy gap of amorphous selenium is found to be 1.99+or-0.02 eV. It reduces drastically on substitution of 2 at.% Sb after which its variation with x is small. The activation energies of Se_1-xSb_x glasses have been determined from the temperature dependence of their electrical resistivities. The activation energy as a function of x also shows a sudden decrease in the range 0.01<or=x<or=0.02. Plausible explanations have been suggested based on the Street-Mott model for charged defect states in amorphous chalcogenides.