Effect of pressure on hopping conduction in amorphous Ge alloys

Toda, Naohiro*; Katayama, Yoshinori; Tsuji, Kazuhiko*

The electrical conductivity has been measured at pressures to 8 GPa and temperatures of 77-300K in evaporated amorphous Ge (a-Ge), a-Ge-Cu alloys and a-Ge-Al alloys. The dependence of is well described by a power lw at low temperatures below 150 K, which is expemcted from a multi-phonon tunneling transition process model with weak electron-lattice coupling, rather than the Mott's variable range hopping conduction model. The exponent in the power law changes with increasing pressure. For both a-GeCu and a-GeAl alloys, d(ln )/d show positive values in the low pressure region and negative values in the high pressure region. Results are discussed from several hopping conduction models.