Effects of different buffer structures on the avalanche behaviour of high voltage diodes under high reverse current conditions

Abstract

The effects of different buffer structures on the avalanche and post avalanche behaviour of high voltage silicon diodes under high reverse current conditions has been investigated. After the onset of avalanche, when the diodes are reverse biased, branches both with positive and negative differential resistance may occur in the device characteristics and depend sensitively on the doping profile of the buffer layer. By numerical device simulation the influence of relevant bulk doping and various buffer profiles on these static reverse characteristics are analysed to understand, clarify and illustrate the breakdown behaviour of high voltage pin-diodes. Based upon these considerations an effective restriction of the electric field maximum at the nn+-junction at the cathode side of the diode can be achieved by adapting the doping gradient of the buffer profile.