High quantum efficiency two color type-II InAs∕GaSb n-i-p-p-i-n photodiodes

Abstract

A $n\text{-}i\text{-}p\text{-}p\text{-}i\text{-}n$ photodiode based on type-II $\mathrm{In}\mathrm{As}∕\mathrm{Ga}\mathrm{Sb}$ superlattice was grown on a GaSb substrate. The two channels, with respective 50% of responsivity cutoff wavelengths at 7.7 and $10\mu \mathrm{m}$ , presented quantum efficiencies (QEs) of 47% and 39% at $77\mathrm{K}$ . The devices can be operated as two diodes for simultaneous detection or as a single $n\text{-}i\text{-}p\text{-}p\text{-}i\text{-}n$ detector for sequential detection. In the latter configuration, the QEs at 5.3 and $8.5\mu \mathrm{m}$ were measured as high as 40% and 39% at $77\mathrm{K}$ . The optical cross-talk between the two channels could be reduced from 0.36 to 0.08 by applying a $50\mathrm{mV}$ bias.