Nitrogen incorporation in InAsN epilayers grown by radio-frequency plasma-assisted molecular beam epitaxy was investigated as a function of growth conditions. Reduced growth rate, growth temperature, and arsenic flux significantly enhance the nitrogen incorporation. Optimal growth conditions allowed us to obtain high quality InAsN with nitrogen composition of up to 2.5%. The epilayers exhibit intense 4K photoluminescence (PL) with double-peak features, which were attributed to free carrier recombination and localized carrier recombination. Strong room temperature PL emission up to a wavelength of 4.5μm is obtained.

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We report the study of photoluminescence (PL) spectroscopy in InAsN epilayers grown by molecular beam epitaxy. All the samples exhibit intense PL emission which persists up to room temperature. Low temperature PL spectra demonstrate double-peak emissions. The dependences of the PL spectra on temperature, laser excitation power and nitrogen composition were investigated. We identified that the short wavelength and long wavelength emissions originate from the band–band transition and the localized states–valence band transition, respectively. The direct observation of the band–band transition implies the high quality of the materials, and a band-gap energy reduction of ∼63 meV at 4 K with 1% nitrogen incorporation was deduced.

Photoreflectance spectroscopy has been applied to study the energy gap and the spin-orbit splitting in InNAs alloys with the nitrogen concentration changing from 0% to 0.88%. It has been observed that the energy gap of InNAs decreases with the increase in nitrogen concentration (about 60 meV per 1% of nitrogen) but the spin-orbit splitting almost does not change. It shows that nitrogen atoms in InNAs alloys influence mainly the conduction band, i.e., shift this band toward the valence band. The bowing parameter for the energy gap and spin-orbit splitting has been determined to be 7.3±0.6 and −0.7±0.4 eV, respectively.

We report on the comparative studies of photoluminescence ͑PL͒ properties of molecular beam epitaxy grown dilute InAsN epilayers with and without antimony ͑Sb͒ flux during the growth. Both samples exhibit strong midinfrared ͑MIR͒ emission at room temperature, while the sample with Sb flux has much higher intensity. At low temperatures, these samples exhibit totally different PL features in terms of line width, peak position, intensity, and their dependences on temperature and excitation density. Our results clearly indicate that part of Sb atoms serve as a surfactant that effectively improves the optical quality of MIR dilute nitrides.