Performance of GaAs JFET at a Cryogenic Temperature for Application to Readout Circuit of High-Impedance Detectors

Abstract

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 /spl mu/V/Hz/sup 1/2/ at 1 Hz and 4.6/spl times/10/sup -19/ A. This result implies that the GaAs JFET 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.