Long-Wavelength InAs/GaSb Superlattice Detectors on InAs Substrates With n-on-p Polarity

Abstract

We report the realization of high-performance long-wavelength infrared detectors with n-on-p polarity based on InAs/GaSb type-II superlattices grown by metalorganic chemical vapor deposition (MOCVD) on InAs substrate. In a normal n-on-p device with PNn heterostructure, Zinc (Zn) is found to diffuse into the critical n-type barrier layer and leads to a high leakage current. By inserting a 200 nm undoped spacer layer after the p-type region is grown, Zn diffusion is completely confined in the spacer layer. The n-on-p device with the spacer shows performances equivalent to those of a p-on-n counterpart, with a dark current density of $6\times 10^{-4}$ A/cm2 at −0.1 V at 80 K, a peak quantum efficiency of ~24%, and 100% cut-off wavelength of $\sim 12~\mu \text{m}$ .