The characteristics of Al-doped ZnO films deposited with RF magnetron sputtering system in various H-2/(Ar+H-2) gas ratios

The properties of Al-doped ZnO (AZO) films were investigated as a function of H-2/(Ar + H-2) gas ratio using an AZO (2 wt% Al2O3) ceramic target in a radio frequency (RF) magnetron sputtering system. The deposition process was done at 200 degrees C and in 2 x 10(-2) Torr working pressure and with various ratios of H-2/(Ar + H-2) gas. During the AZO film deposition process, partial H-2 gas affected the AZO film characteristics. The electron resistivity (similar to 9.21 x 10(-4) Omega cm) was lowest and mobility (similar to 17.8 cm(2)/Vs) was highest in AZO films when the H-2/(Ar + H-2) gas ratio was 2.5%. When the H-2/(Ar + H-2) gas ratio was increased above 2.5%, the electron resistivity increased and mobility decreased with increasing H-2/(Ar + H-2) gas ratio in AZO films. The carrier concentration increased with increasing H-2/(Ar + H-2) gas ratio from 0% to 7.5%. This phenomenon was explained by reaction of hydrogen and oxygen and additional formation of oxygen vacancy. The average optical transmission in the visible light wavelength region over 90% and an orientation of the deposition was [002] orientation for AZO films grown with all H-2/(Ar + H-2) gas ratios.