Effect of KrF excimer laser irradiation on the properties of ZnO thin films

At room temperature, the effect of KrF pulsed excimer laser irradiation on the structural, photoluminescence, and electrical properties and on the surface morphology of ZnO thin films under different laser energy densities was investigated. Compared to the as grown sample, at an irradiation energy density of about 450 mJ/cm(2), the ZnO thin film exhibits a series of desirable properties: UV emission is distinctly higher, resistivity is decreased by three orders of magnitude, and the surface is flat and smooth and, at the same time, it maintains a good epitaxial orientation and a wurtzite crystal lattice structure. UV emission enhancement after laser irradiation is discussed in detail. It is suggested that the mechanism responsible for the UV enhancement is the increase in donors and not the improvement in the crystalline quality. (C) 2008 American Institute of Physics.