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

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 × 10-5A/cm2, 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 7.3×1011cm·Hz1/2/W, which is comparable with that of detectors grown by the molecular beam epitaxy at similar cutoff wavelengths.