EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Using a patterned SiO2 mask we report on selective area growth of III-V materials on high-index GaAs substrates using molecular beam epitaxy (MBE). This platform is used to define 1D semiconductor nanowire (NW) networks with excellent surface selectivity for quantum transport studies. Due to the dependence of NW faceting on the substrate orientation and the trench direction within the oxide mask, non-standard substrate orientations such as (211)A and (211)B, and (311)A and (311)B open the pathway to obtain a multitude of geometries. The NW faceting observed using atomic force microscopy (AFM) and cross-sectional transmission electron microscopy (TEM) is in good agreement with the facets predicted based on the stereographic projections of the substrate orientations. The equilibrium shapes are determined using Wulff construction along with constraints imposed by the oxide mask. Comparison with experimental findings is used to determine whether a particular growth is driven by thermodynamically determined surface energy minimization or by kinetic parameters. The more important advantage of having asymmetric facets is the possibility of enhanced Dresselhaus spin-orbit coupling. The overarching goal is to investigate this phenomenon with magneto-transport measurements.