The electronic properties of inversion domains in a GaN-based lateral polarity heterostructure were investigated using micro-Raman spectroscopy. The piezoelectric polarization of each domain was calculated from strain determined via Raman scattering. The free carrier concentration and electron mobility were deduced from the longitudinal optical phonon-plasmon coupled mode. The electron concentration in the N-face domain was slightly higher than that in the Ga-face domain. It appears that during growth, a larger number of donor impurities may have been incorporated into the N-face domain than into the Ga-face domain.