Annealing studies of heteroepitaxial InSbN on GaAs grown by molecular beam epitaxy for long-wavelength infrared detectors

We report the effect of annealing on the structural, vibrational, electrical, and optical properties of heteropepitaxially grown InSbN epilayers on GaAs substrate by molecular beam epitaxy for long-wavelength infrared detector applications. As-grown epilayers exhibited high N incorporation in the both substitutional and interstitial sites, with N induced defects as evidenced from high resolution x-ray diffraction, secondary ion mass spectroscopy, and room temperature (RT) micro-Raman studies. The as-grown optical band gap was observed at 0.132 eV (∼9.4 μm) and the epilayer exhibited high background carrier concentration at ∼1018 cm−3 range with corresponding mobility of ∼103 cm2/Vs. Ex situ and in situ annealing at 430 °C though led to the loss of N but improved InSb quality due to effective annihilation of N related defects and other lattice defects attested to enhanced InSb LO phonon modes in the corresponding Raman spectra. Further, annealing resulted in the optical absorption edge red shifting to 0.12 eV (∼10.3 μm) and the layers were characterized by reduced background carrier concentration in the ∼1016 cm−3 range with enhanced mobility in ∼104 cm2/Vs range.