Ultrahigh vacuum in situ fabrication of three-dimensional semiconductor structures using a combination of particle beams

Abstract

Focused ion beams have been combined with molecular-beam epitaxy (MBE) in two new in situ processes to produce semiconductor structures. First, a high-energy focused Ga ion beam has been used, during MBE growth interruption, to produce high-quality, vertically isolated ohmic contacts to a two-dimensional electron gas grown in close proximity to an underlying n+ layer. Second, using a focused Sn ion source within the MBE growth chamber, high-quality, electrically active, selected area, n-doped GaAs structures have been grown. In this case, a very low incident energy ion beam (≤50 eV) was used in order to prevent ion damage occurring to the crystal. This was achieved using retarded field ion optics.