Transport properties of bulk amorphous semiconductor Al32Ge68

Abstract Temperature dependences of the dc conductivity and thermopower of bulk amorphous alloy Al32Ge68 were investigated at 6–420 K and at 80–370 K, respectively. The samples were prepared by solid-state amorphisation of a quenched crystalline high-pressure phase while heating from 77 to 400 K at ambient pressure. Amorphous Al32Ge62 was found to be p-type semiconductor with an unusual combination of transport properties. The change of properties was described semi-quantitatively in terms of a modified Mott–Davis model assuming that the Fermi level lies inside the valence band tail.