Inversion-mode Operation of Thermally-oxidized Modulation-doped Silicon Nanowire Field Effect Devices

There has been considerable interest in bottom-up integration of semiconductor nanowires for their application in future logic, memory, and sensor circuits.1,2 Uniformly-doped pand n-type silicon nanowires (SiNWs) of varying carrier density have been synthesized and used to fabricate SiNW field effect transistors (FETs).3'4'5'6 Moreover, dry oxidation of as-grown SiNWs has been shown to suppress the large hysteresis observed in the subthreshold characteristics of unpassivated back-gated SiNW FETs and facilitate fabrication of top-gated SiNW FETs using the SiO2 shell as the gate dielectric.6 However, these SiNW FETs operate by modulation of the Schottky-barrier at the source/drain (S/D) contacts or by depletion of the doped channel, which gives rise to low on-state currents and on-off ratio. In this talk, we will present the results of topgated FETs fabricated using thermally-oxidized SiNWs with axially-modulated n+-p--n+ doping that operate by inversion of the p-channel and show a dramatic improvement in device properties as compared to uniformly-doped SiNW FETs.