Electrical and optical properties of single crystal In2Te3 and Ga2Te3

Electrical conductivity and thermopower measurements are reported for the defect semiconductors p-In2Te3 and n-Ga2Te3. The hole mobility μp in the former varied as Tn where n=+5.98 for T<350 K and n=-4.13 for T>350 K showing a maximum of 210 cm2V-1 sec-1 at 350 K. Electron mobility in n-Ga2Te3 also went through a maximum at 320 K. The optical band-gaps for both were found to be direct, with values of 1.01 and 1.08 eV for In2Te3 and Ga2Te3 respectively at 300 K. Pronounced effects of annealing on TEP and optical absorption gave evidence of defect ordering at low temperatures followed by defect creation at T>350 K.