Using micro-Raman spectroscopy we have investigated the n dopant and strain distribution in lateral epitaxial overgrowth technique GaN films grown by metalorganic chemical vapor deposition on the sapphire (0001) substrates with SiNx masks. The widths of the mask stripes were 2, 4, 8, or 16 μm, while the mask windows were always 4 μm wide. In the case of narrow stripes (2 and 4 μm), when the overgrowth wings were well coalesced, the films were found to be fairly uniform with a background n doping of (4±2)×1017 cm-3. The GaN wings in the samples with 8 and 12 μm stripes did not coalesce, leaving “V”-shaped and trapezoidal grooves, respectively. In the latter case, additional doping [n=(6.5±0.6)×1017 cm-3] of the wing area was revealed, which may be due to surface diffusion of Si atoms from the SiNx mask to the GaN growth front and their incorporation into the growing film. © 2002 American Institute of Physics.