X-ray rocking curve determination of twist and tilt angles in GaN films grown by an epitaxial-lateral-overgrowth technique

X-ray rocking curve measurements have been carried out in order to investig ate the twisting and tilting in hydride vapor phase epitaxy (HVPE) and meta lorganic vapor phase epitaxy (MOVPE) GaN films fabricated by an epitaxial l ateral overgrowth (ELO) technique. The twist angle is directly determined b y means of grazing incidence angle X-ray diffraction. It is found that thes e angles in both MOVPE and HVPE films are significantly reduced by the ELO technique especially for the twist angles. In the MOVPE-ELO GaN film, the t ill and twist angles depend on the stripe direction of the mask pattern: wh ich is closely related to the difference of the growth process.