Selective area epitaxy of GaAs films using patterned graphene on Ge

We demonstrate selective area epitaxy of GaAs films using patterned graphene masks on a Ge (001) substrate. The GaAs selectively grows on exposed regions of the Ge substrate, for graphene spacings as large as 10 microns. The selectivity is highly dependent on the growth temperature and annealing time, which we explain in terms of temperature dependent sticking coefficients and surface diffusion. The high nucleation selectivity over several microns sets constraints on experimental realizations of remote epitaxy.