In this paper we investigate the surface passivation of silicon surfaces by pulsed - DC (p-DC) reactive sputtered Aluminum oxide (AlOx) films as a function of the deposition power density. The p-DC reactive sputtered AlOx deposited at power densities of 1.3 W. cm-2 and 0.13 W. cm-2 showed effective surface recombination velocities (S eff) of 30 cm. s-1 and 107 cm.s-1 respectively on p-type crystalline silicon surface after a post deposition anneal in a N 2 + O2 ambient at 520°C. With increase in power density the deposition rate also increases thus improving the throughput. The density of negative fixed charge in the dielectric or the density of interface states, extracted from metal - oxide - semiconductor capacitors, do not show any significant dependence on deposition power. Cross - sectional Transmission electron microscopy shows the presence of thick interfacial layer for these films. X-ray Photoelectron Spectroscopy (XPS) measurements show a significant difference in the stoichiometry of the deposited film as a function of the deposition power. © 2013 IEEE.