77 K versus 300 K operation: the quasi-saturation behavior of a DMOS device and its fully analytical model

A simulation study on the 77-K versus 300-K operation in terms of the quasi-saturation behavior of a DMOS device using low-temperature PISCES is discussed. From the analysis, a closed-form analytical quasi-saturation model for DMOS devices has been derived. Based on the analysis, for a lightly doped substrate (1×10¹⁵ cm^-3), at 77 K, the drain current at quasi-saturation is higher than that at 300 K. For a heavily doped-substrate (1×10¹⁶ cm^-3), at 77 K, the drain current at quasi-saturation is lower. The difference in drain current at quasi-saturation between 77 K and 300 K for different substrate doping densities is attributed to the incomplete ionization and saturated velocity effects