I need explanation regarding dependence of luminescence on dislocation.
Hi, what kind of dependence you mean, depending on the nature of dislocations it can trap charge carriers leading to non-radiative emission and hence influence the luminescence intensity.
Dislocations can also result in shrinking of the band gap (happens in InGaN due to dislocations being associated with unhomogeneous In content) causing increased luminescence intensity but less eV per photon.
There are many factors that can affect the luminescence intensity of the materials. Among them the synthesis method, the temperature of the synthesis and calcinations of the samples, preparation of the sample for analysis, temperature used during the luminescence analysis, and others. All of these influence the nature of the sample, creating different types of defects increasing or decreasing the band gap. For example, if you have a sample with higher disorder, lower energy transitions take place and the center of the luminescence band tends to dislocate to lower energy values. On the other hand, if you have a balance of the defects on your sample, e.g, a ordered sample, the intensity of the luminescence band tends to increase and higher energy transitions occur dislocating the luminescent band to a higher energy region in the spectrum.
It can depand from type of luminescence: is it carriers recombination (in semiconductors), or internal transitions in some active centers of luminescence. In first case dislocations can cause nonradiative recombination and, in this way, decreasing of luminescence intensity. In second case, as i understand, dislocation deform crystalline lattice around oneself, it change intensity of crystalline electrical field and change energy spectra on luminescence center. So, it can lead to spectral shifting and changing of lifetime.
Something like that..
The study of the photoluminescence spectra is a very sensitive method for studying the influence of intrinsic defects, including dislocations, on the energy structure of crystals. This method together with the structural studies allow you to determine the effects of intrinsic defects on the photoluminescence spectra, and electronic properties of crystals as well as the films. Such study are presented, in particular, in such works:
Journal of Crystal Growth, V. 312, 1726 (2010) and Journal of Photoluminescence V. 132, 2855 (2012)
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