Cathodoluminescence (CL) in the scanning electron microscope has been appli
ed to study the luminescence emission of GaN single crystals grown by LPE m
ethods. CL spectra show the presence of near band edge and of yellow emissi
ons. The latter has been found to be mainly related to rows of hillocks for
med at the growth steps. The origin of the yellow luminescence is discussed
PACS: 78.60Hk; 71.55Eq.