Transport properties of the pressure-induced amorphous semiconductor state ofAl32Ge68

Abstract

The temperature dependences of the dc conductivity and thermopower of the bulkamorphous alloy Al32Ge68 were investigated at 6–420 K and at 80–370 K,respectively. The samples were prepared by solid-state amorphization of aquenched crystalline high-pressure phase while heating from 77 to 400 K atambient pressure. Amorphous Al32Ge68 was found to be a p-type semiconductorwith an unusual combination of transport properties. The behaviour of theproperties was described semi-quantitatively in terms of a modified Mott–Davismodel assuming that the Fermi level lies inside the valence band tail.