Long-wavelength InAs/GaSb superlattice double heterojunction infrared detectors using InPSb/InAs superlattice hole barrier

Abstract

Abstract We demonstrate two double heterojunction long-wavelength infrared detectors based on InAs/GaSb superlattice on InAs substrates grown by metal-organic chemical vapor deposition. In the two structures, the hole barrier employs a novel InPSb/InAs superlattice to achieve conduction-band alignment, while the electron barrier is InAs/GaSb superlattice to achieve valence-band alignment. Two devices with n-type absorber layer and p-type absorber layer exhibit cut-off wavelengths of ∼10.4 μm and ∼12.2 μm, dark current densities of 9 × 10−4 A cm−2 and 2 × 10−2 A cm−2, and specific detectivities of ∼1.7 × 1010 cm Hz1/2 W−1 and ∼1.5 × 1010 cm Hz1/2 W−1, respectively. The device with n-type absorber has a lower dark current due to the natural valence-band alignment, but it has a low quantum efficiency (QE) resulting from the use of n-type absorber layer. In contrast, the device with p-type absorber has a higher dark current that can be possibly attributed to the conduction-band misalignment, but it achieves a higher QE due to the benefits from the p-type absorber.