Initial surface reaction mechanism for atomic layer deposition of HfO2 on the hydroxylated GaAs(001)-4x2 surface using HfCl4 and H2O as precursors is investigated using hybrid density functional theory. The reaction between HfCl4 and H2O with the hydroxylated GaAs(001)-4x2 surface consists of two half-reactions: (1) HfCl4 with GaAs-OH sites and (2) H2O with Hf-Cl sites. The two half-reactions proceed through the formation of stable chemisorbed states, resulting in high activation barriers of 17.1 and 17.6 kcal/mol for HCl formation, respectively. Additional energies are also needed to desorb the respective physisorbed states HCl from the substrate surfaces.
Robin Tobias Andreas Mutschler
Andreas Pautz, Vincent Pierre Lamirand, Pavel Frajtag, Axel Guy Marie Laureau, Yifeng Jiang