Transport properties of a memory-type chalcogenide glass

Transport measurements have been performed on the conducting state of a memory-type chalcogenide glass, of composition Te₈₁Ge₁₅As₄. DC resistivity was measured from 4°K to 300°K and indicates no carrier freeze-out occurs down to 4°K. The resistance ratio, ρ{variant}(300°K)/ρ{variant}(4°K), was found to be 2.5. AC conductivity measurements at room temperature showed only an 18% increase in σ(ω) up to 150 khz. Hall effect experiments at 100 Hz show no dependence of carrier concentration on temperature from 77°K to 300°K, and indicate a room temperature mobility of 85 cm²/V-sec. The sign of the Hall constant implies that the carriers are holes. Resistance was measured as a function of magnetic field from 0 to 140 kOe, at 1.6°K. The magnetoresistance was positive and proportional to H² at low fields, with saturation beginning to set in above about 80 kOe. The results of these studies, taken in conjunction with the X-ray and NMR data, can be used to suggest a plausible model for memory behavior in chalcogenide glasses.