Effects of Thickness Variation on Properties of ZnO Thin Films Grown by Pulsed Laser Deposition

A series of ZnO films with various thicknesses were prepared on (0001) sapphire substrate by PLD. SEM and XRD analysis were utilized to investigate the effects of thickness variation on the surface morphology and the crystallinity. The electrical and optical properties of the films were also investigated as a function of the film thickness. Crystalline quality, electrical and optical properties of the films depended on the film thickness and were improved with increasing the film thickness. This is attributed to the fact that the films thinner than 4000 angstroms are under severe misfit strain, which decreases with increasing film thickness. 22 refs.