On the oscillator strength in dilute nitride quantum wells on GaAs

We have investigated theoretically two kinds of dilute-nitride-based quantum well structures, InGaAsN/GaAs and InGaAsN/GaAsN/GaAs, both able to emit at 1.3 mu m. The ground state transition energy and its oscillator strength have been probed as a function of the material composition in the single particle as well as the excitonic approximations. The modification of the bandgap energy due to nitrogen incorporation has been taken into account by using a two-level repulsion model. We have shown that in spite of a decrease of the electron-hole wave functions overlap with the mole fraction of nitrogen, the overall transition intensity of the excitonic transition can increase significantly due to the strongly composition dependent mass of the exciton. The latter makes dilute nitride quantum wells good candidates for the polaritonic physics and Bose-Einstein condensation of exciton polaritons at telecommunication wavelengths. We have also demonstrated that the exact values of the band offsets are necessary to be known as they have a critical impact on the actual transition oscillator strengths in these quantum wells. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729320]