Ultimate sensitivity of a metal-oxide-metal detector

A calculation was made of the intrinsic noise of metal-oxide-metal structures. This noise consisted of the shot noise resulting from the passage of tunnel currents across the barrier, and of the thermal noise due to the contact resistance. The noise of a point-contact detector (contact area ~1 μ²) was investigated. Measurements at 10 MHz gave the spectral density of the noise which was of the order of 10^–19 W/Hz. Allowance for mismatch of the detector contact relative to the incident radiation was made in a calculation of the responsivity, which was found to be 0.1 V/W. The ultimate sensitivity was of the order of 10^–6 W/Hz^1/2. The application of a bias voltage to the contact increased the ultimate sensitivity to 10^–7 W/Hz^1/2.