Abnormal thyristor forward voltage behaviour: numerical simulation and analytic theory

The on-state current voltage characteristic of thyristors is investigated by numerical one-dimensional simulation. For sufficiently high p-base concentration, an abrupt increase in on-state voltage is observed above a critical current density. By driving the device to higher currents, a reduction of on-state voltage occurs. Similar results are obtained for thyristor profiles with very shallow emitters. An analytic model is presented that explains the phenomena from first principles and leads to a simple criterion for current limiting in terms of Gummel-numbers and carrier mobilities.<
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