Post-deposition annealing challenges for ALD Al$_{0.5}$Si$_{0.5}$O$_x$/n-GaN MOS devices

In this work, we investigate the impact of high-temperature Post-Deposition annealing (PDA) on AlAl$_{0.5}$Si$_{0.5}$O$_x$ deposited by Atomic Layer Deposition (ALD). Reversed hysteresis is observed and explained by mobile charges originating from K$^+$ and Na$^+$ impurities. The high-temperature annealing does not cure the presence of these mobile charges. We also report the onset of film and interface degradation after annealing above 750°C under N$_2$, with both inhomogeneous aluminium and silicon composition, signs of AlSiO crystallization and interfacial gallium oxide growth.