A two-dimensional model for the kink in nMOSTs operating at liquid helium temperatures

Abstract

A model for the kink in MOSTs (MOS transistors) operating at liquid-helium temperatures is presented. It is based on a calculation of the multiplication current as a function of temperature. Subsequently the increase in substrate potential and in drain current is determined, taking account of the current flow through the highly resistive, frozen-out substrate/well. This model makes it possible to explain the temperature and geometry dependence of the kink and can be extended to the case of (cryogenic) SOI (silicon on insulator). With this model it is possible to evaluate and optimize the influence of technological and design parameters for cryogenic applications. It is expected that the well/contact separation plays a crucial role in kink behavior; furthermore, different behavior is expected for n-well technology compared with p-well.<>