Water Vapor-Impermeable AlON/HfOx Bilayer Films Deposited by Hybrid High-Power Impulse Magnetron Sputtering/Radio-Frequency Magnetron Sputtering Processes

Water vapor-impermeable AlON/HfO<i>_x</i> bilayer films were constructed through a hybrid high-power impulse magnetron sputtering (HiPIMS) and radio-frequency magnetron sputtering process (RFMS), applied as an encapsulation of flexible electronics such as organic photovoltaics. The deposition of monolithic and amorphous AlON films through HiPIMS was investigated by varying the duty cycles from 5% to 20%. At an accelerated test condition, 60 °C, and 90% relative humidity, a 100 nm thick monolithic AlON film prepared using a duty cycle of 20% exhibited a low water vapor transmission rate (WVTR) of 0.0903 g m^-2 day^-1 after testing for 336 h. Furthermore, after introducing a nanocrystalline HfO<i>_x</i> film through RFMS, a 214 nm thick AlON/HfO<i>_x</i> bilayer film reached the lowest WVTR of 0.0126 g m^-2 day^-1.