On the performance and surface passivation of type II InAs∕GaSb superlattice photodiodes for the very-long-wavelength infrared

Abstract

We demonstrate very-long-wavelength infrared type II $\mathrm{InAs}∕\mathrm{GaSb}$ superlattice photodiodes with a cutoff wavelength $\left({\lambda }_{c,50\%}\right)$ of $17\mu \mathrm{m}$ . We observed a zero-bias, peak Johnson noise-limited detectivity of $7.63\times {10}^9\mathrm{cm}{\mathrm{Hz}}^{1∕2}∕\mathrm{W}$ at 77 K with a 90%–10% cutoff width of 17 meV, and quantum efficiency of 30%. Variable area diode zero-bias resistance-area product $\left(R_{0}A\right)$ measurements indicated that silicon dioxide passivation increased surface resistivity by nearly a factor of 5, over unpassivated photodiodes, and increased overall $R_{0}A$ uniformity. The bulk $R_{0}A$ at 77 K was found to be $0.08\Omega {\mathrm{cm}}^2$ , with $RA$ increasing more than twofold at 25 mV reverse bias.