Influence of the anisotropy on the performance of D-band SiC IMPATT diodes

Abstract

Numerical simulation has been made to predict the RF performance of \0001[ direction and \11 " 20[ direction p ? /n/n -/n ? (single drift region) 4H silicon carbide (4H-SiC) impact-ionization-avalanche-transit-time (IMPATT) diodes for operation at D-band frequencies. We observed that the output performance of 4H-SiC IMPATT diode is sensitive to the crystal direction of the onedimensional current flow. The simulation results show that \0001[ direction 4H-SiC IMPATT diode provides larger breakdown voltage for its lower electron and hole ionization rates and higher dc-to-rf conversion efficiency (g) for its higher ratio of drift zone voltage drop (V D ) to breakdown voltage (V B ) compared with those for \11 " 20[ direction 4H-SiC IMPATT diode, which lead to highermillimeter-wave power output for \0001[ direction 4H-SiC IMPATT compared to \11 " 20[ direction. However, the quality factor Q for the \11 " 20[ direction 4H-SiC IMPATT diode is lower than that of \0001[ direction, which implies that the \11 " 20[ direction 4H-SiC IMPATT diode exhibits better stability and higher growth rate of microwave oscillation compared with \0001[ direction 4H-SiC IMPATT diode.