Surface reactions in atomic layer deposition of HfO2, ZrO2 and Al2O3 on hydroxylated and sulfur-passivated GaAs(1 0 0) surfaces: A comparative study by density functional theory

The surface reactions in atomic layer deposition (ALD) of HfO2, ZrO2 and Al2O3 on hydroxylated and sulfur-passivated GaAs surfaces are compared by using density functional theory. The HfCl4 and ZrCl4 half-reactions show large similarities in energetics and geometrical structure. However, both of them show large discrepancies with the Al(CH3)3 (TMA) half-reaction. Calculations find that it is more energetically favorable for the Al2O3 deposition than the HfO2 and ZrO2 deposition at the initial ALD stage. In addition, calculations find that although the GaAs passivation with sulfur helps to improve the interfacial properties, it is both kinetically and thermodynamically less favorable.