13 µm cutoff InAs/GaSb type-II superlattice nBn detectors with high quantum efficiency grown by MOCVD
Richard Brown, Chen Liu, George Seager, Francisco Alvarado, Ka Ming Wong, Adam P. Craig, Richard Beanland, Andrew R. J. Marshall, J. Iwan Davies, Qiang LiIn this work, we report the growth and fabrication optimization of a long wavelength InAs/GaSb type-II superlattice (T2SL) nBn detector grown by metal–organic chemical vapor deposition. A GaAs like interfacial scheme was employed to grow the T2SLs matched to InAs substrates. A larger bandgap InAs/GaSb T2SL was used as an electron barrier, removing the need for AlSb based materials within this detector. At 77 K and −0.1 V, the photodetector showed a dark current density of 2.2 × 10−2 A cm−2 and a 100% cutoff wavelength of 13 µm. The external quantum efficiency was found to be 54.4% at 9 µm. The peak detectivity was found to be 4.43 × 1010 cm Hz1/2/W at 9 µm, which is very comparable with similar deep etched detectors grown by molecular beam epitaxy.