Polarized Raman and photoluminescence studies of a sub-micron sized hexagonal AlGaN crystallite for structural and optical properties

摘要

The polarized Raman spectroscopy is capable of giving confirmation regardingthe crystalline phase as well as the crystallographic orientation of thesample. In this context, apart from crystallographic x-ray and electrondiffraction tools, polarized Raman spectroscopy and corresponding spectralimaging can be a promising crystallographic tool for determining bothcrystalline phase and orientation. Sub-micron sized hexagonal AlGaNcrystallites are grown by a simple atmospheric pressure chemical vapordeposition technique using the self catalytic vapor-solid process under N-richcondition. The crystallites are used for the polarized Raman spectra indifferent crystalline orientations along with spectral imaging studies. Theresults obtained from the polarized Raman spectral studies shows singlecrystalline nature of sub-micron sized hexagonal AlGaN crystallites. Opticalproperties of the crystallites for different crystalline orientations are alsostudied using polarized photoluminescence measurements. The influence ofinternal crystal field to the photoluminescence spectra is proposed to explainthe distinctive observation of splitting of emission intensity reported, forthe first time, in case of c-plane oriented single crystalline AlGaNcrystallite as compared to that of m-plane oriented crystallite.