Spectroscopical study of amorphous AsSe : Sn films

The effect of tin impurities on optical spectra of thermally deposited AsSe films doped with Sn (1 to 10 at%) was studied in a wide energy interval fr om 0.8 to 6.2 eV by combination of reflection, absorption, photoresponse an d photocapacitance spectroscopies. Most changes have been detected at the f undamental absorption edge over which a correlation between the band tail w idth and optical gap is demonstrated for various tin concentrations. The ti n induced absorption band associated with a localized energy level at about 1.6 eV in the gap was revealed. Distinct variations in the reflectivity sp ectra of the fundamental absorption region suggest a tin assistance in the formation of the valence band states of the material.