We have constructed a noise measurement setup for high impedance carbon nanotube samples. Our setup, working
in the frequency range of 600 - 900 MHz, takes advantage of the fact that the shot noise power is reasonably large for high
impedance sources so that relatively large, fixed non-matching conditions can be tolerated.
TPrinciple of the shot noise measurement setup. A microwave frequency switch is employed to select either the studied object or a tunnel junction noise source. The noise integrated over the bandwidth 600 - 900 MHz is read either from the output of the Schottky diode detector or from the output of the lock-in amplifier if AC-modulation of current is applied.
Noise vs. bias current measured on a tunnel junction with RtT = 7.7 kΩ. The tunnel junction was made of Al/Al0tx/Al using standard two-angle shadow evaporation.
Setup for shot noise measurements in carbon nanotubes
F. Wu, L. Roschier, T. Tsuneta, M.A. Palaanen, T.H. Wang, and P.J. Hakonen