Abstract Physical modelling of floating-gate avalanche-injection MOS (FAMOS) devices in the program (write) mode is complicated by a feedback effect to the channel from the floating gate. The floating gate takes on a potential by virtue of capacitive coupling to the drain; this induces a channel near the source; the channel injects carriers into the depletion region near the drain and greatly enhances the avalanche multiplication current. This paper presents a simple method for taking account of this effect using empirical data, and thereby arriving at a first-order model of the FAMOS device. Measurements of drain current are subdivided into channel current and avalanche multiplication current, and a constant hot-carrier injection efficiency is assumed. The hot-carrier (avalanche) injection current is associated with a dielectric resistivity, whose dependence on the electric field in the oxide can be approximated by a simple exponential function. Model predictions for the write characteristics of FAMOS devices are in reasonable agreement with experiment.
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