Electrical Conduction of Tl20Ge14Se66

N. M. Megahid ； A. M. Ahmed ； M. M. Ibrahiem

《Chinese Journal of Physics》 35卷5期 (1997/10) Pp. 595-609

並列摘要

For bulk samples of the quenched TlzsCei4Sess either as-prepared or isochronically annealed for one hour at different temperatures up to 150°C, the current-voltage characteristics at different temperatures of measurements (T) and of annealing (Tan) were non-linear especially when the applied potential difference exceeds certain value which is dependent on both T and Tan. The field dependence of the current denity could be described by an empirical power equation. The field enhancement of the electrical conductivity followed an exponential equation. The temperature dependent characteristic length a(T) possessed maximum value at certain values of T and Tan, and becomes lower by about one order of magnitude by annealing. Annealing in the range (100-130”C) was associated with appearance of semimetallic behaviour which characterized the relatively low range of T. Semimetallic-semiconductor transition occurred at particular temperatures depending on that of annealing. Otherwise, semimetallic behaviour extended over the whole range of T. The band to band activation energy changed with the pre-exponential conductivity according to the Meyer-Neldel rule. In the range Tan ≤ 90°C, Mott's formula for hopping conductivity seemed applicable and the characteristic temperature, the density of the localized states, the average hopping distance and the hopping energy were calculated.