Disorder and variable-range hopping conductivity in Cu2ZnSnS4 thin films prepared by flash evaporation and post-thermal treatment

Resistivity, rho(T), of as-grown and annealed Cu2ZnSnS4 films, obtained by flash evaporation, is investigated between T similar to 10 and 300 K. A correlation between the transport properties and the growth conditions of the thin films is also explored. The behavior of rho(T) in the as-grown films exhibits a close proximity to the metal-insulator transition (MIT), whereas annealing shifts the material from the MIT towards an insulating side. This is attributable to an increased microscopic lattice disorder, which is substantiated by the analysis of the Mott variable-range hopping conductivity observed up to T similar to 220-280 K (120-180 K) in the as-grown (annealed) films. An increased width of the acceptor band, a decreased relative acceptor concentration, N/N-c and lower values of the mean density of the localized states, g, are obtained after annealing. (C) 2014 Elsevier B. V. All rights reserved.