Proceedings of the Symposium on Low Temperature Electronics and High Temperature Superconouctivity

This paper discusses the electrical properties of the complementary heterojunction field-effect transistor (CHFET) at 4 K, induding the gate leakage current, the subthreshold transconductance, and the input-referred noise voltage. The CHFET is a GaAs-based transistor analogous in structure and operation to silicon CMOS, and is being explored for possible application in readout electronics operating at 2-4 K. It is shown that CHFET is fully functional at 4 K, with no anomalous behavior, and that the drain current shows the expected dependence on device size and gate voltage. The input-referred noise is on the order of 1 ~V/.JHz at 100 Hz. The gate current is strongly dependent on the doping at the gate edge, and is on the order of 10-I4 amps for devices with the lightest doping. A simple multiplexed op-amp is presented, along with its transfer characteristics at 4 K.