Optimal design of two layered n base in a gate turn-off thyristor

An analysis of a high-voltage GTO (gate turn-off) thyristor structure with a double-layered n base is presented. From integration of Poisson's equation, an expression for the forward blocking voltage at the onset of avalanche breakdown is obtained. Simple design criteria are developed to calculate the optimal thickness and doping density of the n base of a conventional p-n-p-n structure designed for a specific voltage blocking capability. The same principle is applied to design for the doping densities and thicknesses of the high-resistivity region and the buffer layer of the p-i-n GTO structure. The forward blocking voltage as well as the on state voltage (at a current density of 300 A-cm/sup -2/) is predicted for a wide range of base layer thicknesses and doping densities to illustrate the available tradeoff options.<
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