A semi-analytical approach to the evaluation of threshold voltage in depletion MOS's with nonuniformly doped substrates

D.A. Antoniadis' algorithm (ibid., vol.ED-31, no.3, p.303-7, 1984) is extended to cover the computation of threshold voltage for depletion or buried-channel MOSFETs. It is shown that a key factor in its evaluation, of the derivative of the integral charge of the mobile minority carriers in the substrate with respect to the gate-source bias, can easily be calculated using the concept of flat-band capacitance. The threshold voltage is thus computed without requiring strict numerical solution of Poisson's equation, yet the accuracy is very good. This modified algorithm has been implemented in SUPREM III, and good agreement between simulation and experimental results has been achieved.<
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