Performance of GaAs JFET at a cryogenic temperature for application to readout circuit of high-impedance detectors

A GaAs junction field effect transistor (JFET) is a promising candidate for the cryogenic electronics of high-impedance sensitive photoconductors because of its low-noise at low frequencies. This GaAs JFET has advantages compared with other type of FETs, such as no kink phenomena or hysteresis in its current-voltage (I-V) characteristics, small gate leakage currents, and minute capacitance. We report on the noise spectra and leakage current of a SONY n-type GaAs FET in a high-impedance configuration where the gate terminal was surrounded by high-impedance devices at a cryogenic temperature, i.e., 4.2 K. In the high-impedance configuration, we obtained a low noise level and low leakage current of 0.5 muV/Hz(1/2) at 1 Hz and 4.6 x 10(-19) A. This result implies that the GaAs RET is suitable for cryogenic readout electronics. We also discuss the source of the random telegraph signal and the 1 / f noise in the GaAs JFET at cryogenic temperatures.