High-Performance Long-Wavelength InAs/GaSb Superlattice Detectors Grown by MOCVD

Abstract

We demonstrate the high-performance longwavelength InAs/GaSb superlattice (SL) infrared photodetectors based on an Al-free single heterojunction grown by metalorganic chemical vapor deposition. The devices feature a mid-wavelength InAs/GaSb SL p-n junction (PN) and a long-wavelength InAs/GaSb SL n-type absorber (n), so-called PNn design, to reduce the dark current. In addition, a shallow-etch technique was employed by exposing only the mid-wavelength materials during pixel isolation to suppress the surface leakage currents. At 77 K and a bias voltage of -0.1 V, the device exhibited a 50% cutoff wavelength at 8.0 μm, a dark current density of 2.4 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and a peak responsivity of 2.1 A/W. Temperature-dependent dark current measurement indicated the diffusion-limited behavior down to 75 K. The specific detectivity was estimated to be 7.3×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm·Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> /W, which is comparable with that of detectors grown by the molecular beam epitaxy at similar cutoff wavelengths.