NANOFABRICATION OF SI POINT CONTACTS USING GAS-SOURCE MBE - TOWARDS SINGLE-CRYSTALLINE DEVICES

We describe a nanofabrication process for three-dimensional Si point c ontacts with a large single-crystalline constriction region. The proce ss is based on solid-source MBE to grow electrodes of the point contac ts, on gas-source MBE (GSMBE) to grow the constriction region and on e -beam lithography and wet etching to produce nanoholes in the insulato r. From TEM and SEM analysis we find that the GSMBE-grown faceted crys tal, which forms the constriction region, is larger than the nanohole as a result of epitaxial lateral overgrowth. For the process condition s used the largest crystal is four times larger than the hole, so that the ideal point contact structure is approached. Room temperature I-V measurements on fabricated devices are linear and behave according to the Maxwell resistance, as expected for diffusive transport.