Microstructural characterization of patterned gallium arsenide grown on 〈001〉 silicon substrates

Abstract

The microstructure of patterned GaAs grown on Si substrates by molecular beam epitaxy has been examined with both transmission and scanning electron microscopies. The GaAs was found to be single crystal with excellent morphology to the limit of the plasma oxide defining mask. In samples where the native oxide was not completely desorbed from the silicon substrate, the GaAs surface morphology was observed to degrade significantly within 20 μm of the single crystal to polycrystalline transition. Even in the region exhibiting a high density of surface defects, the underlying GaAs remained single crystal. Transmission electron microscopy showed a very low defect density in the center of the patterned growth region. The transition from polycrystalline to single-crystal growth occurred directly above the termination point of the oxide mask.