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

摘要

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 similar to 10.4 mu m and similar to 12.2 mu m, dark current densities of 9 x 10(-4) A cm(-2) and 2 x 10(-2) A cm(-2), and specific detectivities of similar to 1.7 x 10(10) cm Hz(1/2) W-1 and similar to 1.5 x 10(10) cm Hz(1/2) 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.