Molecular Beam Epitaxy of GaAs/AlAs on Mesa Stripes along the [001] Direction for Quantum-Wire Fabrication

Abstract
We report on the growth of GaAs/AlAs layers by molecular beam epitaxy on GaAs (100) substrates patterned with mesa stripes oriented along the [001] direction. The GaAs growth led to the formation of {110} facets which were smoother than the facets formed on [01̄1]- and [01̄1̄]-oriented mesa stripes. It was also found that the GaAs growth rate on the {110} facets is extremely low. We fabricated quantum wire-like structures by narrowing the width of the mesa-top (100) facet, which is limited by the (11̄0) and (110) facets, to the nanometer scale, and then growing an AlAs/GaAs quantum well. The resulting structure was as narrow as ∼30 nm with a thickness of ∼30 nm at its center.