A nanofabrication scheme for InAs/AlSb heterostructures

We report a technique for nanofabrication in the InAs/GaSb/AlSb 6.1 Angstrom material system that utilizes the large difference in the surface Fermi level pinning position for InAs [E-f(s)(InAs)] compared with that for AlSb. An InAs/AlSb single quantum well is capped with a 3 nm, intentionally p-doped InAs layer. As a result of its construction and a relatively low E-f(s)(InAs) there are no free carriers in the InAs/AlSb single quantum well making the quantum well insulating as-grown. Simply by selectively removing the thin p-doped InAs cap layer with a wet etch, the surface Fermi level becomes pinned on AlSb and shifted upward by half an electron volt. This results in a drastic change in band bending and creates a conducting electron channel in the buried InAs quantum well. We demonstrate with experiment and the support of a self-consistent band bending calculation that this scheme is highly effective for nanofabrication. (C) 2002 American Institute of Physics.