A high performance 4H-SiC normally-off VJFET

This paper presents the design, fabrication and characterisation of a high performance 4H-SiC normally-off, trenched and implanted vertical junction field-effect transistor (VJFET). Devices with different trenched mesa widths were designed and their performance investigated. The fabricated VJFETs demonstrated a 3.9Omega resistance at V
_G
=5 V (with negligible gate current) and J
_D
=154 A/cm
²
, corresponding to a low specific on-resistance of 3.7 mOmegacm
²
for a normally-off VJFET blocking voltage up to 1,734 V (at V
_G
=0 V). The specific on-resistance is more than 200 times smaller than that of the theoretical limit of Si FETs. The figure-of-merit (FOM, V
_bt

²
/R
_ON-sp
), is equal to 815 MW/cm
²
for the demonstrated VJFET, substantially surpassing the best FOM of any kind of unipolar and bipolar SiC power switches