Analysis of current voltage characteristics of MWIR homojunction photodiodes for uncooled operation

摘要

Dark currents n ~+/ν/p ~+ Hg _(0.69)Cd _(0.31)Te mid wave infrared photodiodes were measured at room temperature. The diodes exhibited negative differential resistance at room-temperature, but with increasing leakage currents as a function of reverse bias. The current-voltage characteristics were simulated and fitted by incorporating trap assisted tunneling via traps and Shockley-Read-Hall generation recombination process due to dislocations in the carrier transport equations. The thermal suppression of carriers was simulated by taking energy level of trap (E _t), trap density (N _t) and the doping concentrations of n ~+ and ν regions as fitting parameters. Values of E _t and N _t were 0.78E _g and ～6-9 × 10 ~(14) cm ~(-3) respectively for most of the diodes. Variable temperature current voltage measurements on variable area diode array (VADA) structures confirmed the fact that variation in zero bias resistance area product (R _0A) is related to g-r processes originating from variation in concentration and kind of defects that intersect a junction area.