Fabrication of Aharonov-Bohm rings in Si/SiGe heterostructure

A sub-micron trenching technique has been developed to fabricate Aharonov-Bohm ring structures in a high mobility Si/Si0.7Ge0.3 modulation doped heterostructure. Scanning electron-beam lithography is used to expose the area defining the ring contour, and reactive-ion etching follows to recess this area, thus forcing electrons to flow inside the ring. Conductance in the Si/SiGe rings exhibits oscillations in magnetoresistance, which is the first observation of this effect in Si-based materials. The amplitude of the oscillations is comparable to that of similar devices on similar mobility GaAs/GaAlAs heterostructures. © 1995 Elsevier Science B.V. All rights reserved.