Search for new transparent conductors: Effect of Ge doping on the conductivity of Ga_2O_3, In_2O_3 and Ga_(1:4)In_(0:6)O_3

摘要

Only a small amount (≤3.5mol) of Ge can be doped in Ga _2O_3, Ga_(1.4)In_(0.6)O_3 and In_2O_3 by means of solid state reactions at 1400°C. All these samples are optically transparent in the visible range, but Ge-doped Ga_2O_3 and Ga_(1.4)In_(0.6)O_3 are insulating. Only Ge-doped In_2O_3 exhibits a significant decrease in resistivity, the resistivity decreasing further on thermal quenching and H_2 reduction. The resistivity of 2.7 Ge-doped In _2O_3 after H_2 reduction shows a metallic behavior, and a resistivity of ～1mΩcm at room temperature, comparable to that of Sn-doped In_2O_3.