Computer-aided design consideration on low-loss p-i-n diodes

Two methods are presented to realize a low forward-voltage p-i-n diode with a thin i region. One is to increase recombination current by appropriately controlling carrier lifetime in the i region. The recombination current for a constant voltage reaches a maximum at a carrier lifetime given by
(q/kT) W\min{i}\max{2}/8\mu_{i}
, where W
i
and μ
i
are thickness and effective mobility of the i region, respectively. The other is to increase diffusion current in the p emitter by decreasing carrier lifetime only for the high impurity concentration region. On the basis of the first method, diodes with a 0.83-V forward voltage at 150 A/cm
²
, a 200-V reverse voltage, and a 50-ns reverse recovery time were obtained.