A noise detection scheme with 10 mK noise temperature resolution for semiconductor single electron tunneling devices

The experimental requirements for low frequency electrical noise measurements of single electron tunneling (SET) semiconductor samples are discussed and a two-channel cross-correlation spectrum analysis method combined with ultralow noise detection is proposed which gives 10 mK noise temperature resolution. We emphasize the effect of the high frequency photon radiation originating from the external circuit which may strongly affect sub-kelvin low frequency noise measurements if not filtered. We quantitatively show that hot photons are important as a mechanism of activation of electron traps for semiconductor SET devices, increasing low frequency 1/f or telegraphic noise, and as a mechanism to increase the electronic temperature. We describe a new type of cryogenic coaxes whose attenuation drastically thermalizes the photons. As a check, we show for the first time resonant tunneling peak linewidths in the Coulomb blockade regime decreasing with temperature down to ≃60 mK.