Effects of Laser-annealing Using a KrF Excimer Laser on the Surface, Structural, Optical, and Electrical Properties of AlZnO Thin Films

The effects of laser-annealing using a KrF excimer laser on the material properties of AlZnO thin films prepared by r.f. magnetron sputtering were investigated. After laser-annealing, the electrical resistivity was observed to be significantly decreased while no considerable change in the average optical transmittance in the visible wavelength region was observed. The improved electrical conductivity is attributed to increases in both the carrier concentration and the carrier mobility. These results are expected to come from the increased effective areas of the grain boundaries and from the activation of Al dopants due to improved surface and structural properties, respectively. Namely, after laser-annealing, the increased effective areas of the grain boundaries induce an increase in the carrier mobility because of decreased depletion regions with potential barriers which may impede carrier motions, and the improved crystal quality, indicative of the effective incorporation of Al dopants, causes an increase in the carrier concentration.