Photoluminescence behaviour of GaInNAs quantum wells annealed at high temperature

The photoluminescence (PL) characteristics of GaInNAs quantum wells (QWs) after high temperature post-growth annealing were studied. The QWs were grown using a radio frequency (RF) nitrogen plasma source in conjunction with a solid source molecular beam epitaxy (SSMBE) system. It is found that annealing at high temperature (840°C) and long duration (10min) results in significant improvement in the PL characteristics of the GaInNAs QWs. The PL intensity of the GaInNAs QW could improve by as much as 30 times after annealing, and its full-width-at-half-maximum (FWHM) reduces from 63.1meV to a small value of 16.3meV after annealing. There are two blueshift regions in the wavelength shift vs. nitrogen composition curve that shows the GaInNAs PL blueshift after annealing as a function of nitrogen composition. For as-grown GaInNAs QWs with a low nitrogen composition of less than ∼1% (Region A), increasing indium composition from 22% to 30% during growth results in an increase of PL blueshift (after annealing) from 72nm to 87nm. On the other hand, for the as-grown GaInNAs QWs having higher nitrogen compositions of ∼1% to ∼3% (Region B), indium compositions (within the range of 19.5% and 25%) was found to have insignificant effect on the PL blueshift. In fact, the PL blueshift (as a result of annealing) increases rapidly from 72nm to ∼200nm. The dominant mechanisms that give rise to the blueshift of the PL peak wavelength in GaInNAs QWs are proposed based on the PL, X-ray diffraction (XRD) and reflection high electron energy diffraction (RHEED) observations. The investigation has important implications for the growth of GaInNAs-based laser emitting at 1.31 μm wavelength.