  The polarized Raman spectroscopy is capable of giving confirmation regarding
the crystalline phase as well as the crystallographic orientation of the
sample. In this context, apart from crystallographic x-ray and electron
diffraction tools, polarized Raman spectroscopy and corresponding spectral
imaging can be a promising crystallographic tool for determining both
crystalline phase and orientation. Sub-micron sized hexagonal AlGaN
crystallites are grown by a simple atmospheric pressure chemical vapor
deposition technique using the self catalytic vapor-solid process under N-rich
condition. The crystallites are used for the polarized Raman spectra in
different crystalline orientations along with spectral imaging studies. The
results obtained from the polarized Raman spectral studies shows single
crystalline nature of sub-micron sized hexagonal AlGaN crystallites. Optical
properties of the crystallites for different crystalline orientations are also
studied using polarized photoluminescence measurements. The influence of
internal crystal field to the photoluminescence spectra is proposed to explain
the distinctive observation of splitting of emission intensity reported, for
the first time, in case of c-plane oriented single crystalline AlGaN
crystallite as compared to that of m-plane oriented crystallite.
