On the electrical conductivity of CdTe thin films evaporated onto unheatedsubstrates

The electrical conductivity, sigma, of CdTe semiconducting thin films (d = 90-1200 nm) prepared by physical vapor deposition onto unheated glass subst rates was investigated. Depending on the source temperature, films with (11 1) texture or an amorphous structure were obtained. At room temperature, th e values of sigma for as deposited films ranged from 10(-6) to 10(-4) Omega (-1) m(-1). The effects of source temperature and post-deposition heat trea tment on the temperature dependence of the electrical conductivity of the f ilms were studied. By in situ measurement of film resistivity during heatin g-cooling cycles, an irreversible dependence of sigma was revealed for the films with amorphous structure. The results are discussed in relation with film recrystallization during the annealing process. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.