Physical evaluation and electrical properties in glassy semiconductors a-GeTe4Mx

Abstract

Amorphous films of the ternary GeTe 4 M x , where M=In and Cu and x represented by 0.05 and 0.10 with thickness about 200 nm, have been prepared by thermal evaporation. Dark conductivity measurement on thin films are reported in the temperature range 100–350 K. The results indicate that at the first slope which is represented by the range from 250 to 350 K, the conduction occurs 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 variable range hopping, which is in reasonable agreement with Mott’s condition of 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 correlations between the chalcogenide glass forming ability and the number of lone-pair electrons for chalcogenide system. An attempt has been made to evaluate this correlation according to simple criterion for computing the ability of a chalcogenide system to retain its vitreous states proposed by Liang. The effect of heat treatment and substrate on the structure transformation is investigated by scanning electron microscope.