Photoluminescence

Low temperature photoluminescence in the strongly disordered dilute nitride GaAsN
Calculated PL spectra for finite temperature over 1000 random potential super-cell configurations.
Calculated PL spectra for finite temperature over 1000 random potential super-cell configurations.

Photoluminescence (PL) is one of the most useful techniques to investigate structural disorder in nanostructure materials. The PL spectrum of the system is formed as a result of the competition between electron-phonon scattering and electron-hole recombination. Our aim is to calculate the time-independent PL spectra for strongly disordered dilute nitride GaAsN at finite temperatures.

To calculate the PL spectra we solve the kinetic equation which describes electron distribution at low excitation. The equation comprises: (1) non-equilibrium distribution of electron-hole pairs; (2) phonon assisted transition rate; and (3) electron-hole recombination rate (Rlum).

Exciton energy levels and wave functions are calculated numerically in a super-cell geometry, using the Born-Oppenheimer approximation for the electron-hole wave function in the presence of a random alloy potential acting on the electron. The strength of the random potential is calculated from experimentally measured value of the mobility of electrons at room temperature. The phonon assisted transition rate is proportional to the charge overlap between states, the phonon density of states, and the phonon occupation number. Our results suggest that our fairly simple model is capable of calculating the PL spectra at low temperatures, comparable with the experiment.

References
[1] A.M.Mintairov et al., Phys. Rev. Lett. 87 (2001) 277401.

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