EFFECT OF SODIUM ON THE STATIONARY DARK AND PHOTOCONDUCTIVITY OF AMORPHOUS GE30SE70

Stationary dark and photoconductivity, and their temperature dependenc e, have been studied for Ge30Se70 bulk samples to which up to 0.8% of NaSe have been added. Strong increases in the dark conductivity and mo dest ones in the photoconductivity are observed. These increases are s imilar to the ones observed when pure germanium selenide films are dep osited on Na-containing substrates. The photoconductivity increase is ascribed to sodium photosensitization: while the large, nearly tempera ture-independent contribution to the dark conductivity relates to hopp ing between highly conducting regions.