Lattice Location of N in InxGa1x As1yNy Dilute Nitrogen Alloys

Dilute nitrides, in particular InxGa1-xAs1-yNy are very interesting alloys because of their actual and potential applications in the field of telecommunications and photovoltaics. A full knowledge of the local structure around each kind of atom, in particular the local ordering, is of fundamental importance because it is predicted to affect the electronics properties of these alloys. In this work we investigated the local environment of N and In by X-Ray absorption Fine Structure (XAFS). By exploiting the polarization dependency of XAFS we were able to demonstrate that N is fully substitutional to As. The lineshapes of the N K-edge XANES spectra are in fact identical, setting different grazing angles, which is a fingerprint of the cubic geometry of the N site. This information has been exploited to generate atomic clusters that very well simulate the experimental N K-edge XANES in the Full Multiple Scattering approach and to elaborate a multi-shell fit for XAFS data at the In K-edge. We concluded that N preferentially links In atoms, even if this short range ordering is by far weaker than the predicted one