Initial surface reactions in atomic layer deposition ofAl2O3 on the hydroxylatedGaAs(001)-4 × 2 surface

Abstract

Hybrid density functional theory has been used to investigate theinitial surface reaction mechanism in atomic layer deposition (ALD) ofAl2O3 on the hydroxylatedGaAs(001)-4 × 2 surface. The precursors for ALD ofAl2O3 are trimethylaluminium(TMA) and H2O as the aluminium and oxygen sources. For the first half-reaction betweenTMA with the GaAs surface the calculated activation barrier is15.4 kcal mol−1, andthe H2O half-reaction proceeds by a mechanism similar to that of the first half-reaction, resulting in an activationbarrier of 27.6 kcal mol−1. Both half-reactions are thermodynamically favourable, exothermic by 52.0 and43.6 kcal mol−1 relative to the reactants, respectively.