Undoped and aluminium-doped zinc oxide films have been prepared by thermal evaporation of zinc acetate [Zn(CH3COO)(2) 2H(2)O] and aluminium chloride [AlCl3] onto a heated glass substrate. The structural and optoelectrical properties of the films have been studied. The effects of heat treatment for the as-deposited films in air and vaccum are investigated. Highly transparent films with conductivity as low as 2 x 10(-3) Omega cm can be produced by controlling the deposition parameters. The electron carrier densities are in the range 0.2-7 x 10(19) cm(-3) with mobilities of 22-58 cm(2) V-1 s(-1). (C) 2000 Elsevier Science B.V. All rights reserved.