A non-invasive SOI gating method of probing pristine chemically-terminated silicon surfaces

Silicon has a variety of surface terminations available to it in which surface states are passivated and where 2D electron inversion layers are possible through electrostatic gating. Here, Si(111) surfaces are terminated with hydrogen using a simple wet chemical treatment, and techniques to probe 2D transport on these passivated surfaces have been established. We are presently developing new techniques to probe pristine hydrogen-terminated Si surfaces using a non-invasive SOI flip-chip gating assembly in which all critical device fabrication is performed on the SOI end. Extremely high mobilities, in excess of 300,000 cm²/Vs, have been demonstrated in our previous generation devices, and further refinement of these novel techniques to preserve the pristine nature of these passivated Si surfaces is expected to yield even higher mobilities. Until now, we have focused exclusively on H-Si(111), but are in process of extending our study to include H-Si(100) surfaces. Further, recent progress in halogen-terminated (Cl, Br, I) Si surfaces has provided new avenues for future investigation using our device platform. Architecture details and ohmic contact tests will be presented as well as ongoing low temperature device characterization measurements.