We study the native charge compensation effect in Mg doped GaN nanorods (NRs), grown by Plasma Assisted Molecular Beam Epitaxy (PAMBE), using Raman, photoluminescence (PL) and X-ray photoelectron spectroscopies (XPS). The XPS valence band analysis shows that upon Mg incorporation the E F -E V BM reduces, suggesting the compensation of the native n-type character of GaN NRs. Raman spectroscopic studies on these samples reveal that the line shape of longitudinal phonon plasmon (LPP) coupled mode is sensitive to Mg concentration and hence to background n-type carrier density. We estimate a two order of native charge compensation in GaN NRs upon Mg-doping with a concentration of 10 19 -10 20 atoms cm −3 . Room temperature (RT) PL measurements and our previous electronic structure calculations are used to identify the atomistic origin of this compensation effect.Epitaxially grown semiconductor nanostructures such as quantum dots, nanowires and nanorods of III-V materials have been investigated extensively in the literature 1-4 . The interest of studies on these nanostructured materials lies in the facts that it offer an extra degree of freedom to manipulate it's material properties in comparison to bulk form. The enhanced performance of nanostructure based devices is partly due to the effective lateral stress relaxation as a consequence of the presence of facet edges and sidewalls. These crystal facets also minimize or eliminate the formation of dislocations, and consequently leads to the fabrication of nearly defect-free III-V semiconductor nanostructures with large surface to volume ratios 5,6 . 1D NRs offer several advantages over the planar structure such as reduced dislocation density 7,8 , lower polarization field 9 , and enhanced light output efficiency 10 . This approach can also reduce the cost of LED fabrication on large-area Si substrates. Thus, Growth, characterization and optimization of single crystalline nitride NRs have been of great interest, which has the tremendous potential for technological applications.Various techniques such as Hall measurements, C-V measurements etc, have been employed to study the electronic properties like carrier density, mobility etc., of semiconducting films. These techniques require preparation of Ohmic contacts on the films, which is very difficult for nanostructures such as NRs, NWs etc., due to their discontinuity and small dimensions. Raman spectroscopy is a very powerful technique to study material properties of nitride semiconductors. It is well known that formed GaN films are intrinsically n-type and the background carrier densities are to the order of 10 17 -10 19 cm −3 . Often the oscillation of such high free electron densities are collective and referred as plasmons. The plasmon oscillations of these free carriers couple with Raman active a) These two authors contributed equally b) Electronic mail: smsprasad@jncasr.ac.in longitudinal optical (LO) phonon modes via its associated longitudinal electric field gives rise to longitudinal phonon-plasmon(LPP) coupled m...
