Mapping of Donor Impurities in Gan By Raman Imaging

Raman scattering experiments on silicon-doped GaN show that donor impurities quench the Al(LO) Raman line at 735 cm −1 . This is due to interaction between lattice vibrations and the free carrier plasma. The spatial variation of the Al(LO) signal has been imaged directly using newly developed instrumentation. Features with dimension under on micron are observed in faceted GaN crystallites. The variation in free carrier concentration is attributed to preferential incorporation of donor impurities during growth.