Self-consistent charge control modelling of InP based HFET structures

The results of a theoretical study of the charge control characteristics of different n-channel InP-based HFETs are presented. The calculations involve determining the variation of the two-dimensional electron gas (2DEG) density, n/sub s/, with gate bias, V/sub G/, from the self-consistent solution of the one-dimensional forms of Poisson's equation and the single electron Schroedinger equation. The prospect of implementing enhancement mode and depletion mode FETs for direct-coupled FET logic (DCFL) by using SISFETs with pseudomorphic n/sup +/ contacts is demonstrated. For MODFETs the compromise between maximizing the transconductance (g/sub m/) or the gate voltage range giving peak g/sub m/ is discussed, and performance improvements are reported for stepped well channel structures.<
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