Crystals having various dislocation densities were characterized using micro-

Raman spectroscopy. Defects and strain in the GaN layer were examined via

measurements of the Raman shift and the width of the TO phonon bands. The

broadening of Raman bands in GaN crystals occurred as the dislocation density

increased. An up-shift of the peak frequencies corresponding to compressive strain

was observed for hetero-epitaxial samples grown by MOCVD and MBE. The inplane

distribution of defects and strain in epilayers with various dislocation

densities was also examined by Raman mapping. The Raman maps showed that the

examined phonon frequency and bandwidth fluctuated spatially. An increase in

dislocation density in GaN epilayers introduced not only broadening of Raman

bands but also increased fluctuations.

Raman Scattering Analysis of GaN with Various Dislocation Densities.

T.Kitamura, S.Nakashima, N.Nakamura, K.Furuta, H.Okumura: Physica Status

Solidi C, 2008, 5[6], 1789-91