A comparative study of the noise performance of aluminium-gallium-arsenide/gallium-arsenide high electron mobility transistors with and without superconducting gate electrodes

The noise performance of an AlGaAs high electron mobility transistor (HEMT) with a 1 mu m vanadium/titanium superconducting gate electrode is compared to an otherwise identical nonsuperconducting titanium gate HEMT. At a frequency of 1 GHz and at a temperature below its critical temperature, the superconducting gate HEMT achieved a noise temperature of 21 K. Under these conditions the HEMT with the Ti gate electrode demonstrated a noise temperature of approximately 70 K. This factor of three reduction in noise temperature is due to the reduced gate resistance of the V/Ti superconducting gate. This is the first demonstration of noise reduction in an HEMT using a low-temperature superconducting gate electrode.<>