Temperature-dependent interface stability of MoO3/GaAs(001) hybrid structures

We report on the influence of growth temperature and post-growth annealing on interface formation and film structure of thin MoO3 films on GaAs(001), which plays an important role for a future application as carrier-selective contacts or diffusion barriers in III/V-semiconductor spin- and optoelectronics or photovoltaics. Growth and post-growth annealing were performed in a manner that emulates heterostructure growth and lithographic processing. High-resolution transmission electron microscopy reveals nanocrystalline (“amorphous”) growth at temperatures up to 200∘C and a transition to polycrystalline growth at about 400∘C. Spatially resolved chemical analysis by energy dispersive x-ray spectroscopy reveals strong intermixing at the MoO3/GaAs(001) interface proceeding during both film deposition and annealing. Our results evidence the important role of intermixing occurring during the process of interface formation at the very beginning of deposition.