Tuning the desorption temperature of an As cap layer allows to achieve In0.53Ga0.47As(001) surfaces with (2 × 4) and (4 × 2) reconstructions which exhibit different chemical reactivity upon exposure in atmospheric pressure. Trimethyl-Al based atomic layer deposition of Al2O3 films on the two exposed surfaces causes a non-equivalent interface composition. This behavior is associated with a worse electrical quality of the interface with the exposed (4 × 2) In0.53Ga0.47As reconstruction.