Optical reduction of low frequency noise in cryogenic GaAs junction field effect transistor

We demonstrated optical low frequency noise reduction in a n-type SONY GaAs junction field effect transistor (JFET) (gate width: 5 mu m; length: 1 mu m) operating at 4.2 K. At 1 Hz, a 6 dB decrease and a 10 dB increase in noise were observed when the JFET (band gap: 1.51 eV) was illuminated by light with wavelengths of 1650 and 1550 nm, respectively, for a drain voltage of 0.5 V and drain current of 0.25 mu A. When the drain current was 0.5 mu A, 1650 nm illumination increased the noise; moreover, hysteretic behavior in response to the illumination was also observed. These results show that deep level trapped charges apparently affect low frequency noise, which can be controlled by illumination using photons whose energies are below the band gap energy at cryogenic temperatures. (c) 2008 American Institute of Physics.