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.<>