We demonstrate selective area epitaxy of GaAs films using patterned graphene masks on a
Ge (001) substrate. GaAs selectively grows on exposed regions of the Ge substrate for
graphene stripe widths of 10 μm. 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
micrometers sets constraints on experimental realizations of remote epitaxy.