Transport properties of bulk amorphous semiconductor Al32Ge68

Temperature dependences of the dc conductivity and thermopower of bulk amor phous alloy Al32Ge68 were investigated at 6-420 K and at 80-370 K, respecti vely. 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 u nusual combination of transport properties. The change of properties was de scribed semi-quantitatively in terms of a modified Mott-Davis model assumin g that the Fermi level lies inside the valence band tail. (C) 2001 Elsevier Science B.V. All rights reserved.