Optical properties and mechanisms of current flow in Cu2ZnSnS4 films prepared by spray pyrolysis

Thin films Cu2ZnSnS4 (up to 0.9 mu m thick) with p-type conductivity and band gap E (g) = 1.54 eV have been prepared by the spray pyrolysis of 0.1 M aqueous solutions of the salts CuCl2 center dot 2H(2)O, ZnCl2 center dot 2H(2)O, SnCl4 center dot 5H(2)O, and (NH2)(2)CS at a temperature T (S) = 290A degrees C. The electrophysical properties of the films have been analyzed using the model for polycrystalline materials with electrically active grain boundaries. The energy and geometric parameters of the grain boundaries have been determined as follows: the height of the barriers is E (b) a parts per thousand 0.045-0.048 eV, and the thickness of the depletion region is delta a parts per thousand 3.25 nm. The effective concentrations of charge carriers p (0) = 3.16 x 10(18) cm(-3) and their mobilities in crystallites mu (p) = 85 cm(2)/(V s) have been found using the technique for determining the kinetic parameters from the absorption spectra of thin films at a photon energy h nu a parts per thousand E (g) . The density of states at grain boundaries N (t) = 9.57 x 10(11) cm(-2) has been estimated.