Statistics of excitonic energy states based on phononic-excitonic-radiative model

Abstract

Excitation and deexcitation dynamics of excitons in GaN are analyzed by theoretical simulation using a set of rate equations based on a phononic-excitonic-radiative (PXR) model, which is applied to the analysis of experimentally-observed photoluminescence (PL) properties using a short pulse excitation. In phononic processes, deformation and piezoelectric interactions of the LA phonon and Fröhlich interaction of the LO phonon are taken into account. This model is successfully applied to the analysis of experimentally-observed emission line intensity ratios for excitons. This analysis reveals that the strong population exchange between the state of the principal quantum number n = 2 and the continuum takes place due to the increase in temperature. Further, the long experimental radiative lifetime component in the temporal PL decay curve up to 100 ns at room temperature (RT) is attributed to the shift of the population distribution to higher n states, which work as population reservoirs of the n = 1 state. Theoretical calculation using this model suggests that the dominant phonon mode in the excitation transfers from the n = 1 and 2 states shifts from the LA phonon to the LO phonon due to the increase in temperature from 130 K to 240 K. The PXR simulation model is feasible for the analysis of exciton-carrier dynamics and radiation efficiency analyses.