Polycrystalline films of undoped p-type GaSb0.8As0.2 with different thicknesses ranging from 0.1 to 1 mu m were grown on glass substrates at a substrate temperature of 300 degrees C by molecular-beam deposition. Hall-effect measurements in the temperature range of 10-400 K revealed the coexisting valence-band and impurity-band conduction. A differential Hall-effect method was applied for the purpose of obtaining concentration and mobility of holes in the surface-side region of the film eliminating the effects of the underlying substrate-side region. Furthermore, a two-band conduction model was applied for the purpose of obtaining concentration and mobility of holes in the valence band eliminating the effects of the impurity-band conduction. The concentrations of a shallow acceptor level, a deep acceptor level, and a compensating donor level are deduced through fitting the experimental temperature dependence of valence-band hole concentration by the solution of the charge-balance equation. The mean value and the standard deviation of the grain-boundary barrier height as well as the mean free path are deduced through fitting the experimental temperature dependence of mobility by assuming the thermionic emission of holes over grain-boundary potential barriers with fluctuated heights. The estimated results of the above parameters are presented as a function of the distance from the substrate interface. Especially, it is shown that the mean free path of valence-band holes is almost unchanged while the height of grain-boundary potential barriers decreases with the distance from the substrate. The obtained results suggest the necessity of improving the electrical properties of GaSbAs layers near at the beginning of their deposition by some method, e. g., by inserting buffer layers, in the practical application for thin film transistors. (C) 2013 Elsevier B. V. All rights reserved.