A numerical simulation of the transient drain current in a MOST at cryogenic temperatures

The authors present a numerical technique to model the transient in the drain current when the MOS transistor is suddenly switched on at low temperatures. The technique is similar to those used in steady-state simulations of MOS devices. However, the physical principles that apply to a transient simulation are very different from those of the steady-state model. Consequently, new boundary conditions and new physical relationships that predict semiconductor charge densities are derived. The transient predicted by the simulation is compared to the measured data, verifying the principles upon which the simulation is based. The simulation shows that the field-enhanced ionization of dopant atoms can be accurately modeled using Shockley-Read-Hall statistics and Poole-Frenkel expressions. The hole capture cross-section for the acceptor atoms was about 2×10^-12 cm²