LARGE CHANGES IN THE ELECTRICAL-CONDUCTIVITY OF TETRAHEDRALLY-COORDINATED CHALCOGENIDE GLASSES CONTAINING OXYGEN

For glassy (Cu2/3S1/3)(x)(As2/5S3/5)(1-x) with x=9/19 [Cu6As4S9] the S and Cu atoms are tetrahedrally coordinated, the As atoms are three-fold coordinated, and there exist only Cu-S and As-S bonds. With the addition of oxygen to films sputtered at this composition, the activation energy for the conductivity decreases from approximately 0.4 eV to less than 0.1 eV and the room temperature conductivity increases from about 10(-4) Omega(-1) cm(-1) to greater than 1 Omega(-1) cm(-1). Optical absorption measurements are consistent with these conductivity results. These results are compared to similar measurements in the Cu-As-Se system.