High-resolution X-ray diffraction (HRXRD) study of laser debonded AlGaN/GaN high electron mobility transistors (HEMTs), grown by metal-organic chemical vapor deposition (MOCVD), is performed. The lattice parameters as well as the in-plane and out-of-plane strains of the transistors before and after laser lift-off are determined from theta-2 theta X-ray diffraction spectra. The biaxial strains of the laser debonded HEMTs in a- and c-directions compared with the non-debonded HEMTs are extracted from the measured strain. The results clearly indicate stress relaxation in the device after laser debonding. Additionally, the full-width at half-maximum (FWHM) of the X-ray rocking curves are compared before and after laser debonding. The results do not indicate any increase in the dislocation densities in the heterojunction after laser debonding. This corroborates with the studies on the I-V characteristics of the devices, which also indicate no degradation in the electronic properties after laser debonding. (c) 2006 Elsevier B.V. All rights reserved.