Annealing studies of undoped and indium-doped films of zinc oxide

Annealing studies in vacuum, oxygen and air ambients were carried out on undoped and indium-doped films of zinc oxide deposited by spray pyrolysis. The effects of annealing on the electrical properties of these films are explained in terms of the chemisorption and desorption of oxygen at the grain boundaries, which in turn lead to the creation or annihilation of extrinsic trap states. The effect of the presence of these trap states on the electronic transport properties of different types of films is explained on the basis of the grain boundary carrier-trapping model