High Structural Quality of Type II InAs/GaSb Superlattices for Very Long Wavelength Infrared Detection by Interface Control

We investigate the interface control for very long wavelength infrared InAs/GaSb superlattice (SL) structures. An InAs/GaSb SL photodetector with very high structural quality has been demonstrated by precisely controlling the Sb-soak, the growth stop time and the InSb layer thickness at the interfaces. The full width at half maximum of the X-ray diffraction satellite peaks of a p-i-n device structure is only 21 arcsec. The 50% cutoff wavelength of the detector is 14.5 μm at 77 K. At 14.5 μm, the quantum efficiency is 14%, while at the photoresponse maximum position of 7.7 μm it is 50%.