Modelling of the double-diffused MOST's with self-aligned gates

The physical properties of double-diffused MOS transistors (DDMOST)' first reported by Tarui et al in 1969 have so far received only limited attention in the literature. While their potential for microwave operation has been demonstrated, the physical effects of a non-constant channel impurity density have not been discussed, nor has the problem of calculating the saturation characteristics been considered in any depth. It is the purpose of this paper to discuss these aspects of DDMOST operation and to relate them to experimentally determined device characteristics.