Defects containing point defects, impurities, and intentionally doping in GaN, are the subject of numerous experimental and theoretical investigations. It is well known that their presence can reduce the performance of optoelectronic devices due to a multiplicity of parasitic luminescence which they are responsible.
While it is now well known that yellow luminescence (YL) around 2.2 – 2.3 eV observed in undoped GaN layers results from a transition between band states and deep levels, the origin of the defects that are associated with this YL is still under debate.
Cathodoluminescence studies have recently shown that the YL is not uniform in the crystal and therefore can be associated with the presence of extended defects like dislocations and grain boundaries. Then, several atomistic models of extended defects may be considered in order to explore the ones that give rise to the parasitic YL.
In this work, molecular static atomistic simulations using a Self-Consistent-Charge Dentity-Functional-Tight-Binding (SCC-DFTB) approach will be applied to study the core structure of tilt boundaries in interaction with gallium and nitrogen interstitials. The geometry of the nearest neighbours, the formation energies and the electronic states associated to these defects will be discussed in comparison with those in GaN bulk and dislocations.