Impurity States and Impurity Conduction in Tellurium under Hydrostatic Pressure

Abstract

Under the hydrostatic pressure up to 4.7 kbar, the impurity states in undoped and Sb-doped single crystal tellurium are investigated by measuring the conductivities and Hall coefficients in the temperature region from 77 K to 1.4 K. The pressure dependences of the conductivity and Hall coefficient are different between undoped and Sb-doped crystal at low temperature. This indicates that there are two kinds of impurity states in tellurium, one is the impurity band-like states degenerate in the top of the valence band and the other is the ordinary acceptor states formed by group V impurities. Pressure dependences of these impurity states are discussed and in Sb-doped tellurium the possibility of the pressure-induced metal-insulator transition in impurity conduction is proposed.