Thickness-dependent properties of indium-doped ZnO films

Abstract

The thickness dependence of microstructural, electrical and optical properties of transparent conducting indium-doped ZnO films was studied. The density of trap states due to chemisorbed oxygen at the grain boundaries was found to depend on the orientation of grains which, in turn, depended on the film thickness. The thickness dependence of the electrical parameters of oxygen-annealed films was explained on the basis of changes in the trap state density. The changes in the electrical parameters of vacuum-annealed films were attributed to a decrease in grain size. The shifts in optical gap on vacuum and oxygen annealing were attributed to changes in carrier concentration, considering two simultaneous effects on band gap widening and narrowing.