The effect of edge dislocations on optical properties in wurtzite ZnO was studied using a k·p multiband Hamiltonian model. An edge dislocation was modelled as a negatively charged line due to its electron-acceptor nature with an elastic strain field due to the lattice distortion around the dislocation. The electrostatic potential strength of the negatively charged dislocation depended upon the filling fraction, which describes the fraction of acceptor sites occupied by trapped electrons along the dislocation line. To understand the effect of electrostatic potential strength, the filling fraction was varied here. Using the calculated energy levels and wave functions for electrons and holes from the kp multiband Hamiltonian, the spontaneous emission spectrum was obtained as a function of dislocation density and filling fraction. The calculated results were compared with available experimental photoluminescence data. The band edge peak intensity decreases significantly with increasing dislocation density. It was found that the electrostatic potential strength did not affect the band edge peak emission, but it generates deep level emissions. For low filling fractions, corresponding to high temperature, the most commonly observed green luminescence was found. For a high filling fraction, corresponding to low temperature, the green luminescence shifts to red luminescence, which was consistent with experimental observation.

Edge Dislocation Effect on Optical Properties in Wurtzite ZnO. Stroud, A., You, J.H.: Journal of Crystal Growth, 2012, 340[1], 92–7