Physical evaluation and electrical properties in glassy semiconductors a-GeTe4Mx

Amorphous films of the ternary GeTe4Mx, where M = In and Cu and x represent ed by 0.05 and 0.10 with thickness about 200 nm, have been prepared by ther mal evaporation. Dark conductivity measurement on thin films are reported i n the temperature range 100-350 K. The results indicate that at the first s lope which is represented by the range from 250 to 350 K, the conduction oc curs in the band tails of localized states and at the second slope which is represented by the range from 100 to 250 K, the conduction is due to varia ble range hopping, which is in reasonable agreement with Mott's condition o f variable range hopping conduction. Some parameters such as coordination number <r >. the number of constraints per atom N-con were calculated. It was found that there is a number of cor relations between the chalcogenide glass forming ability and the number of lone-pair electrons for chalcogenide system. An attempt has been made to ev aluate this correlation according to simple criterion for computing the abi lity of a chalcogenide system to retain its vitreous states proposed by Lia ng. The effect of heat treatment and substrate on the structure transformat ion is investigated by scanning electron microscope. (C) 2001 Elsevier Scie nce B.V. All rights reserved.