Strain analysis of InGaN/GaN multi quantum well LED structures

Five period InGaN/GaN multi quantum well (MQW) light emitting diode (LED) structures were grown by a metalorganic chemical vapor deposition (MOCVD) system on c-plane sapphire. The structural characteristics as a strain-stress analysis of hexagonal epilayers MQWs were determined by using nondestructive high resolution x-ray diffraction (HRXRD) in detail. The strain/stress analysis in AlN, GaN, and InGaN thin films with a variation of the In molar fraction in the InGaN well layers was conducted based on the precise measurement of the lattice parameters. The a- and c-lattice parameters of the structures were calculated from the peak positions obtained by rocking the theta axis at the vicinity of the symmetric and asymmetric plane reflection angles, followed by the in-plane and out-of-plane strains. The biaxial and hydrostatic components of the strain were extracted from the obtained a- and c-direction strains values.