Quantification of Superiority of Broad-Buffer Diodes

Abstract

We have quantitatively shown the superiority of broad-buffer (BB) diodes over conventional p–i–n diodes, especially with regard to fast and soft reverse recovery, by measuring a new quantity, Γ, signifying the degree of reverse recovery oscillation (RRO). The performance of switching devices has been evaluated in terms of the forward voltage drop VF and the reverse recovery loss ERR up to now, but these quantities cannot assess the inhibition of the RRO, which is another important property of switching devices. The quantity Γ, defined as the difference between the voltage rating and the RRO threshold power-supply voltage, represents how well the RRO is inhibited. We evaluated the performance of diodes having a variety of doping profiles in the n-drift region by numerically calculating VF, ERR, and Γ and plotting these quantities in a three-dimensional evaluation space. Our device simulation results clearly show that the values of Γ as well as VF and ERR for BB diodes are significantly lower than those for conventional diodes, and that BB diodes should be classified as a new category of diodes in view of their superior reverse recovery characteristics.