Investigation of silicon field-effect transistors in cryogenic amplifiers for radio frequency superconducting quantum interference devices

Abstract

We have prepared n-channel silicon field-effect transistors, which are capable of working at liquid helium temperatures (4.2 K) and used them in cooled preamplifiers for rf superconducting quantum interference device (SQUID) readout electronics. All metallizations of these transistors were made of niobium, to study the possibility of a further integration of a SQUID and FET on the same chip. Using the FETs in a cooled preamplifier together with a rf SQUID gradiometer, the flux noise of the system could be reduced by a factor of 3 compared to a room temperature low noise preamplifier. We have also performed calculations of a possible increase of the substrate temperature due to the power dissipation of the FET and have measured the cross talk between FET and SQUID.