DIRECT IMAGING OF IMPURITY-INDUCED RAMAN-SCATTERING IN GAN

The donor impurity distribution in a GaN epitaxial layer was studied u sing Raman imaging. The Al(LO) Raman line at 735 cm(-1) is found to be inversely correlated to the presence of silicon in GaN due to phonon interaction with the free carrier plasma associated with donor impurit ies in the material. The spatial variation of the AI(LO) signal was im aged directly using newly developed instrumentation. Features with dim ension of about 0.5 mu m are observed in faceted GaN crystallites. Thi s variation in free carrier concentration is attributed to preferentia l donor impurity incorporation during growth. (C) 1996 American Instit ute of Physics.