Photoluminescence in InAsN epilayers grown by molecular beam epitaxy

Abstract

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.

Structural and optical properties of dilute InAsN grown by molecular beam epitaxy

“…The temperature and power dependence of the PL emission of these samples was the subject of previous work. 12,13 Optical absorption experiments were recorded by using a BOMEM DA.8 rapid scanning FTIR interferometer. For these measurements, a globar source, a KBr beam-splitter and an MCT detector were employed.…”

“…5,9,[11][12][13]18 The results are usually analyzed in terms of the BAC model, which allows one to calculate the fundamental band gap energy of InAs 1−x N x ͑i.e., the energy of the E − subband͒ as a function of composition…”

“…32 Regarding the RT optical emission, the broad PL features observed in these samples are attributed to band-to-band transitions. 12,13 At lower temperatures, emission at longer wavelengths arising from recombination of localized electrons and delocalized holes is also detected. 12,13 Nevertheless, the RT PL signal is usually very weak, and, therefore, high power densities on the samples are employed.…”

“…12,13 At lower temperatures, emission at longer wavelengths arising from recombination of localized electrons and delocalized holes is also detected. 12,13 Nevertheless, the RT PL signal is usually very weak, and, therefore, high power densities on the samples are employed. Thus, it cannot be ruled out that the RT PL emission is blueshifted by band-gap filling effects originated by strong freecarrier photogeneration.…”

“…More recently, the effect of the growth conditions on the incorporation of N in InAsN/InAs epilayers was investigated. 12,13 High quality samples with nitrogen compositions up to 2.5% were obtained, with intense low-temperature PL emission and relatively strong room-temperature ͑RT͒ PL emission at a wave-length of 4.5 m. Photoreflectance ͑PR͒ studies on similar epilayers allowed probing the dependence on N content of both the band gap and the spin-orbit splitting of InAsN up to a N concentration of 0.88%. 18 It was concluded that only the conduction states are affected by N, in agreement with the results obtained in the Ga͑In͒AsN alloy system and fully consistent within the framework of the band-anticrossing ͑BAC͒ model.…”