Kink-related low-frequency noise overshoot in Si NMOSTs at liquid helium temperatures

In this paper, the excess low-frequency noise observed in an Si MOSFET operating at liquid He temperatures is investigated in detail. More specifically, the influence of both temperature and bias voltage on the kink-related noise overshoot is reported and discussed in view of a recently proposed model. It will be demonstrated that the noise overshoot is drastically reduced for operation temperatures above 10 K, or if the device has a floating, or forward-biased substrate/well contact. For the first time, it will be shown that the magnitude of the “kink noise” has a hysteretic character, as does the drain current in the kink region. This is accompanied by a change in the nature of the low-frequency noise spectrum. A more refined model will be derived, relating the excess noise to the applied drain, gate and substrate bias. A good, qualitative agreement with the measurements is obtained by this approach.