Vol:.(1234567890) Electronic Materials Letters (2018) 14:784–792 https://doi.org/10.1007/s13391-018-0074-6 1 3 An Alternative X‑ray Difraction Analysis for Comprehensive Determination of Structural Properties in Compositionally Graded Strained AlGaN Epilayers Palash Das 1,2,5  · Sanjay Kumar Jana 1,4  · Nripendra N. Halder 1  · S. Mallik 2  · S. S. Mahato 2  · A. K. Panda 2  · Peter P. Chow 3  · Dhrubes Biswas 1 Received: 12 July 2017 / Accepted: 12 April 2018 / Published online: 31 May 2018 © The Korean Institute of Metals and Materials 2018 Abstract In this letter, a standard deviation based optimization technique has been applied on High Resolution X-ray Difraction sym- metric and asymmetric scan results to accurately determine the Aluminum molar fraction and lattice relaxation of Molecular Beam Epitaxy grown compositionally graded Aluminum Gallium Nitride (AlGaN)/Aluminum Nitride/Gallium Nitride (GaN) heterostructures. Mathews–Blakeslee critical thickness model has been applied in an alternative way to determine the partially relaxed AlGaN epilayer thicknesses. The coupling coefcient determination has been presented in a diferent perspective involving sample tilt method by ofset between the asymmetric planes of GaN and AlGaN. Sample tilt is further increased to determine mosaic tilt ranging between 0.01° and 0.1°. * Palash Das d.palash@gmail.com 1 Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India 2 National Institute of Science and Technology, Berhampur, Odisha 761008, India 3 SVT Associates, 7620 Executive Drive, Eden Prairie, Minneapolis, MN 55344, USA 4 National Institute of Technology Sikkim, South Sikkim 737 139, India 5 Present Address: National Institute of Science and Technology, Berhampur, Odisha 761008, India