Fabrication and Dark Current Analysis of InAsSb-Based nBn Structures for High-Performance Mid-Infrared Applications

This study presents a comprehensive characterization and dark current analysis of InAsSb-based nBn structures for high operating temperature (HOT) mid-wavelength infrared (MWIR) applications. InAsSb layers with varying Sb compositions were grown by molecular beam epitaxy (MBE) to achieve lattice match and minimize dislocation density. High-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), and reciprocal space mapping (RSM) were employed to assess crystal quality, strain relaxation, and surface morphology, demonstrating significant improvements with optimized growth conditions. The fabricated nBn photodetectors, featuring a lattice-matched AlAsSb barrier, exhibited a low dark current density of 4.5 × 10^-5 A/cm² at 130 K and 2.6 × 10^-4 A/cm² at 190 K. Blackbody-calibrated photocurrent spectroscopy confirmed that the InAsSb MWIR photodetectors exhibited excellent performance at 160 K, achieving peak quantum efficiency (QE) of 58%, a responsivity of 1.69 A/W, and a detectivity of 2.13 × 10¹¹ cm Hz^1/2/W at 3.58 μm, demonstrating their potential for high-temperature infrared detection applications.