Effect of Surface Morphology on the On-state Resistance of SiC Photoconductive Semiconductor Switches

摘要

The photoconductive semiconductor switches (PCSS) were fabricated on V-doped semi-insulating 6H-SiC. We studied the effect of surface morphology on the on-state resistance of SiC PCSS. The SiC wafers with quite similar physical properties were processed by mechanical polishing, chemical mechanical polishing and H_2 etching for producing different surface morphologies. All the SiC PCSS were excited by a 355 nm laser with a frequency of 10 Hz and a pulse intensity of 132 μJ/mm~2. We found that the surface morphology had an obvious effect on the on-state resistance. The PCSS fabricated on mechanical polished SiC wafer with an average surface roughness (rms) of 1.0 nm showed the largest on-state resistance of 45.6 ohms, while a low on-state resistance of 13.3 ohms was observed for the wafer processed by H_2 etching at high temperature.