CMOS-Compatible SOI MESFETs With High Breakdown Voltage

The authors demonstrate that silicon-on-insulator (SOI) MESFETs can be fabricated alongside SOI CMOS with no changes to the foundry process flow. The MESFETs operate in depletion mode with a threshold voltage of -0.6 V for a gate length of 0.6 mum. The breakdown voltage of the MESFETs greatly exceeds that of the CMOS devices and varies in the range of 12-58 V depending upon the channel access length, i.e., the distance from the edge of the gate to the edge of the drain region. For MESFETs with a gate length of 0.6 mum and an access length of 0.6 mum, the peak cutoff frequency exceeds 7 GHz. The maximum available gain increases with drain bias and values of f
_max
range from 17 GHz at V
_DD
= 2 V to 22 GHz at V
_DD
= 8 V