Setup of shot noise measurement in a tunnel junction for noise thermometry

We report our development of a low-temperature shot noise measurement set-up for noise thermometry. We have constructed an experimental set-up for measuring shot noise in the frequency range of 700-1000 MHz. We have fabricated metallic tunnel-junction devices consisting of Al-AlO
_x
-Al by two angle-evaporation method. The current-voltage characteristic of the tunnel junction showed an ohmic behavior up to bias voltage of ~3k
_B
T/e at room temperature. Also, the characteristics of RF components including RF amplifiers, circulators, directional couplers were investigated.