EFFECT OF A VALENCE-BAND BARRIER ON THE QUANTUM EFFICIENCY AND BACKGROUND-LIMITED DYNAMIC RESISTANCE OF COMPOSITIONALLY GRADED HGCDTE P-ON-N HETEROJUNCTION PHOTODIODES

A new analytical model for the bias-dependent quantum efficiency of a HgCdTe P-on-n heterojunction photodiode with a valence band barrier el ucidates the important physics of the phenomenon and shows that the ba ckground-induced shunt resistance is a result of the same mechanism, t hat is, a tendency of the light-induced carriers to pile up in the bas e layer due to the retarding field produced by the barrier. A paramete rized version of the model agrees well with experimental current-vs-vo ltage and noise measurements.