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The Bipolar FieldEffect Transistor Theory (B. Latest Advances)
CT Sah, B.B. Jie University of Florida, US
Keywords: bipolar fieldeffect transistor, electrochemical potential theory, driftdiffusion theory, basicbuildingblock
Abstract: Latest advances are presented on theoretical device and circuit characterizations of the Bipolar Field effect transistor (BiFET) [1]. The 2 Dimensional (2 D) rectangular geometry of the transistor (uniform in the width direction) is employed to separate the 2 D equations into two surface electric potential coupled 1 D equations, enabling generic baseline solutions, without 2 D features which are then treated as modifications of the 1 D solutions. The 1952 Shockley 2 section volume channel geometry model of Junction Gate (JG) FET is applied to the surface and volume channels of the MOS BiFET, designated as an emitter and a collector sections, each can simultaneously have electron and hole, surface or volume channels. The exactly identical (near thermal equilibrium, no hot carriers) electrochemical potential (ECP or quasi Fermi potential) and drift diffusion (DD) approaches are employed. Numerical results are readily obtained for the analytical ECP, but tedious for the DD theory requiring analytical approximations. Asymptotic approach to 1 Gate from 2 Gate, and from impure Base to pure Base are illustrated. Deviations of DD theory from ECP theory are demonstrated. Two Dimensional geometric effects near intersections of the four electrodes (Gate 1, Gate 2, Source and Drain) are described. DC characteristics are computed and presented for both the traditional transistor device and also the basic building block (BBB [2]) circuit function configurations.
Nanotech 2008 Conference Program Abstract
