Rectifying Source and Drain Contacts for Effective Carrier Transport Modulation of Extremely Doped SiC Nanowire FETs

Abstract

Back-gated field effect transistors (FETs) based on catalyst-free grown 3C-SiC nanowires (NWs) were fabricated and the electrical characterization revealed electron conduction through the NWs. Devices with either ohmic or rectifying contacts have been observed leading to two different operation modes. The transistors with ohmic-like contacts manifest a very weak gating effect and the device switching OFF is not achievable even for high negative gate voltages due to the high electron concentration along the NWs. In contrast, the Schottky contact barrier (SB) at source (S)/ drain (D) regions acts beneficially for the FET performance by suppressing the off current. At high positive gate voltages (>;20 V), the SBs tend to be more transparent leading to ION/ IOFF ratio equal to ~103 in contrast to the weak gating effect of the ohmic contact 3C-SiC NWFETs. Therefore, in the case of highly doped NWs, where the direct effect of the gate voltage on the accumulated carriers is negligible, SB-NWFET presents improved performance by suppressing the off current and indirectly modulating the drain current through the control of SBs transparency at source and drain regions.