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A comparative study of the simulated breakdown voltage of 4H-SiC devices has been conducted for the most widely used impact ionization models (Selberherr, Hatakeyama), based on the experimental data of 4H-SiC pn diodes. The effect of mesh density on the simulated breakdown voltage has been examined. The TCAD simulations employing default commercial simulators parameters did not converge to a value close to the experimentally observed as the mesh density is increased. Various experimental ionization parameters, as reported in the bibliography, have been examined instead of the commercial-TCAD-simulators default ones. Simulations with optimal parameters result in convergence to breakdown voltage values close to the experimentally measured ones when the mesh density is increased.

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.

The 4H-SiC p-i-n diodes were designed, fabricated, and characterized for use in microwave applications. The diodes with mesa structure diameters between 80 and 150 /spl mu/m, exhibited a blocking voltage of 1100 V, a 100-mA differential resistance of 1-2 /spl Omega/, a capacitance below 0.5 pF at a punchthrough voltage of 100 V and a carrier effective lifetime between 15-27 ns. X-band microwave switches based on 4H-SiC p-i-n diodes are demonstrated for the first time. The switches exhibited insertion loss as low as 0.7 dB, isolation up to 25 dB and were able to handle microwave power up to 2.2 kW in isolation mode and up to 0.4 kW in insertion mode.

4H-SiC p/sup +/-n-n/sup +/ diodes of low series resistivity (