<title>Modeling of fast conductivity phenomena in semiconductors</title>

Abstract

A simple transmission line model, which seeks to explain fast conductivity phenomena in semiconductors, such as photoconductivity or avalanching (induced by either light or displacement current waves), is proposed. The model relies on breaking up the semiconductor drift space into small cells, each of which contains an imaginary transmission line element so as to allow an electromagnetic wave to propagate away from the generated plasma. The same transmission line may be used to convey light energy produced in the semiconductor. The transmission line also serves as the energy storage element. Time varying nodal resistors, located at the transmission line junctions, control the conductivity. The nodal resistors embody the physics of the semiconductor, whereas the transmission line matrix accounts for energy spread. Slower semiconductor mechanisms, such as carrier drift, may be easily incorporated into the formalism, if necessary. The model points out the importance of triggering either an avalanche or displacement current wave in regions where the static field is high. Under certain conditions the model predicts a growing electromagnetic wave with sufficient amplitude to sustain avalanching.