A 0.8 THz $f_{\rm MAX}$ SiGe HBT Operating at 4.3 K

We demonstrate record ac performance (0.8 THz) for a silicon-germanium heterojunction bipolar transistor (SiGe HBT) operating at cryogenic temperatures. An extracted peak f
_MAX
of 798 GHz (peak f
_T
of 479 GHz) at 4.3 K was measured for a device with a BV
_CEO
of 1.67 V. This scaled SiGe HBT also exhibits excellent thermal properties, as required from an electro-thermal reliability perspective. Taken together, these results strongly suggest that at the limits of scaling, robust, and manufacturable SiGe HBTs designed for room temperature operation are likely to achieve THz speeds.