Thermal annealing using ultra-short laser pulses to improve the electrical properties of Al:ZnO thin films

Abstract Industrial-grade Al:ZnO thin films, were annealed by UV picosecond laser irradiation in argon atmosphere. A remarkable increase of both the carrier density and electron mobility was measured, while the optical properties in the 400-1000 nm range did not change significantly. We studied the microstructure of the films, in order to explain the observed macroscopical changes upon ultra-short pulsed laser annealing. The effects of the ps-laser irradiation are shown to be attributed to the formation of defects and a local atomic rearrangement on the sub-nm scale. This interpretation is rigorously based on the cross-referenced analysis of different experimental techniques (i.e. SEM, AFM, positron annihilation, optical spectroscopy, Hall measurements, Raman spectroscopy, XPS and XRD). The results of this study can be used to develop a new, viable, technological processing technique to further improve Al:ZnO electrodes.