  A thorough investigation of local structure, influencing macroscopic
properties of the solid is of potential interest. We investigated the local
structure of GaN nanowires (NWs) with different native defect concentration
synthesized by the chemical vapor deposition technique. Extended X-ray
absorption fine structure (EXAFS) analysis and semi-empirical and the density
functional theory (DFT) calculations were used to address the effect of dopant
incorporation along with other defects on the co-ordination number and bond
length values. The decrease of the bond length values along preferential
crystal axes in the local tetrahedral structure of GaN emphasizes the preferred
lattice site for oxygen doping. The preferential bond length contraction is
corroborated by the simulations. We have also studied the impact on the local
atomic configuration of GaN NWs with Al incorporation. AlxGa1-xN NWs are
synthesized via novel ion beam techniques of ion beam mixing and
post-irradiation diffusion process. The change in the local tetrahedral
structure of GaN with Al incorporation is investigated by EXAFS analysis. The
analysis provides a clear understanding of choosing a suitable process for
ternary III-nitride random alloy formation. The local structure study with the
EXAFS analysis is corroborated with the observed macroscopic properties studied
using Raman spectroscopy.
