HEMTs for low-power and low-frequency noise 4.2 K cryoelectronics : fabrication and characterization

Abstract
Pseudomorphic (Al,In)GaAs/GaAs HEMTs for low-power and low-frequency noise 4.2K cryoelectronics have been fabricated and characterized. At 4.2K, neither collapse nor kink effect has been detected. Large drain-current variation from sub-nano to milli-Ampere has been obtained with a gate-bias variation of about half a volt. In the low drain-current range, this current can attain its saturation regime with a drain-bias of about 0.1V. For noise characteristics, a I/f noise of 1.9nV/Hz^0,5 at 1kHz, a white noise less than 0.5nV/Hz^0,5 and a very low shot noise of 0.76 fA/Hz^0,5 have been reached with a power supply less than 10µW. In addition, the input noise, drain-current and transconductance as a function of the gate bias have been investigated at a fixed drain-bias. Clear correlation between them has been found, therefore, the lowest input noise operating condition might be estimated.