9503708 Zaslavsky The addition of this processing extension equipment will enable new research in nansostructure fabrication by regrowth and in the transport, optical properties, and device physics of novel nanostructures. This processing extension will permit regrowth of modulation-doping, contacting and isolating layers on patterned heterostructures prepared with in-situ etched and clearned regrowth surfaces. The processing extension will have the following capabilities: low-damage electron-cyclotron resonance (ECR) plasma reactive ion etching of III-V semiconductors; ECR hydrogen plasma cleaning of etched substrates; surface cleanliness monitoring by Auger spectroscopy; and invacuum transfer of patterned substrates into the MBE growth chamber. The properties of strained and unstained uniform quantum wires fabricated by etching through quantum wells and regrowth with modulation-doping layers on the sidewalls will be studied. A heavily-doped gate electrode layer in the regrowth sequence will permit carrier density modulation in these wires independent of the confining potentials determined by the original heterostructure. Analogously, by pregrowing the appropriate barrier potentials, gated 2-dimensional tunneling structures and superlattices in III-V heterostructures will be fabricated and their transport and optical properties will be investigated down to the quantum dot limit. % This equipment will be used by a group of investigators having complimentary expertise ranging from semiconductor epitaxial growth to nanofabrication and fro transport and optical characterization to device physics and engineering. It represents fundamental materials research important for understanding processing of semiconductor materials, and is ultimately relevant for manufacturing.
