Exciton acoustic-phonon coupling in single GaN/AlN quantum dots

Abstract

Coupling of acoustic phonons to excitons in single wurtzite-type GaN/AlN quantum dots is investigated in detail by cathodoluminescence experiments and compared to theory. Numerical simulations of the coupling in the framework of the independent Boson model with realistic wave functions based on 8-band $\mathbf{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbf{p}$ theory show good agreement with observed emission line shapes. We analyze the influence of the geometry and the built-in dipole moment of the quantum dots on the spectral distribution of phonon-coupling strength and the different coupling mechanisms. We observe considerable contribution of the transversal phonons via piezoelectric coupling. The omnipresent broadening of the zero-phonon line is discussed in terms of spectral diffusion.