Optical and Electrical Characterization of Hydrogenated GaInZnO Thin Films

GaInZnO (GIZO), 120-nm thick, thin films have been deposited on 100-nm SiO2/(100) Si wafers by RF magnetron sputtering and were subsequently heated in a forming gas (5 % H-2 in N-2) for hydrogenation or in pure N-2 gas for annealing it various temperatures. Broad photoluminescence (PL) spectra, peaking at about 715 run, are observed in as-deposited GIZO films and are attributed to oxygen-deficient defects. The PL intensity is sharply decreased by hydrogenation at temperatures (T) >= 300 degrees C. The conductivity of the hydrogenated films shows an increasing behavior up to 400 degrees C, but above 400 degrees C, it, shows a decreasing behavior with increasing T tip to 650 degrees C. The effects of hydrogenation on the PL and the conductivity of the films are much larger than those of annealing. These results suggest, that hydrogen atoms are substitutionally incorporated in GIZO films as shallow donors, producing free carriers and that the defect centers are greatly reduced by hydrogen passivation of the oxygen vacancies, resulting, in an enhanced conductivity and a reduced PL intensity.