FREEZE-OUT EFFECTS ON NMOS TRANSISTOR CHARACTERISTICS AT 4.2-K

Detailed substrate current characteristics of nMOSTs at 4.2 K were obtained with a view to elucidating their transient (hysteresis) and kink behavior below carrier freeze-out. A great similarity with room-temperature behavior is found, indicating that analogous expressions for the substrate current IB can be used to calculate the transient time constant that follows from the forced depletion layer formation (FDLF) model reported previously by the authors. In a second part to this work, it will be demonstrated that both the substrate and the cooling bias have a marked influence on the kink. These effects can be fully understood with the FDLF model.