Crystal tilts in epitaxially laterally overgrown GaN films determined by four-circle x-ray diffraction

Crystal tilts in epitaxially laterally overgrown (ELO) GaN films via hydrid e vapour phase epitaxy (HVPE) on sapphire substrates have been investigated by using the four-circle x-ray diffraction method. Three diffraction peaks corresponding to the (0002) reflection of vertically epitaxial and tilted GaN domains are observable in the x-ray rocking curve. The angle separation s Delta omega between the main peak and two lobes change with the azimuth a ngle phi. The dependence of Delta omega on phi and the crystal tilt angle t heta has been calculated based on the standard kinetic x-ray diffraction mo del. The crystal tilt angle of a typical HVPE ELO GaN sample has been deter mined to be 2.379 degrees.