InAs/GaSb superlattice photodetector with cutoff wavelength around 12 μm based on an Al-free nBn structure grown by MOCVD

Abstract

We report the design, growth, fabrication and characterization of a long-wavelength InAs/GaSb superlattice (SL) infrared photodetector based on an nBn structure grown by metal-organic chemical vapor deposition. A lightly-doped n-type mid-wavelength InAs/GaSb SL was employed as the electron barrier to the long-wavelength InAs/GaSb SL absorber, avoiding the use of any Al-contained materials in the design. At 77 K and a bias of −0.16 V, the photodetector shows a cut-off wavelength around 12 μm and a dark current density of 2.6 × 10−3 A cm−2. The peak responsivity was measured to be 3.4 A W−1, resulting a specific detectivity as high as 1.1 × 1011 cm Hz1/2/W at 10.3 μm.