Electrical Conduction of GeSe at Low Temperatures

The Hall coefficient and resistivity of germanium monoselenide were measured between 320 and 1.5 K. The ionization energy of the acceptor is estimated from the temperature dependence of the Hall coefficient. It changes from 3.9 to 5.3 meV according to the heat treatment. The impurity conduction is found to occur at low temperatures. There appear two activation energies corresponding to impurity conduction, the first of about 1.5 meV and the other of about 0.5 meV. The former value can be associated with the thermal excitation of holes from the Fermi level to a mobility edge in the upper Hubbard band.