A Comprehensive Study on the Geometrical Effects in High-Power 4H–SiC BJTs

Geometrical effects on the forward characteristics of high-power bipolar junction transistors are studied. An implantation-free area optimized junction termination is implemented in order to have a stable breakdown voltage. The effect of varying the emitter-base geometry, i.e., the emitter width (W
_E
), the base width (W
_B
), emitter contact-emitter edge distance (W
_n
), and base contact-emitter edge (W
_p
) on the on-state characteristics is studied in the different emitter cell geometries. The emitter size effect shows the highest influence on the current gain (fi). It shows a significant effect on the fi (single finger design, about 61%; square cell geometry, about 98%; hexagon cell geometry, about 90%). The base size effect also shows a significant improvement on the fi of about 23% at a given W
_E
.