We have carried out defect-induced Raman scattering in resonance with yellow-luminescence (YL) transitions in GaN
layers grown on sapphire by electron cyclotron resonance-molecular beam epitaxy technique. The photoluminescence (PL) data shows strong excitonic peaks in the near-band-edge region apart from the weak and broad yellowluminescence transitions. Raman spectra from various GaN samples prepared by this technique show strong and distinct
Raman peaks in the low-energy region (90}260 cm-1). These peaks are attributed to electronic excitations of donors,
which are involved in the yellow-luminescence transitions. Resonant enhancement of these peaks is seen as a function of temperature.