Simulating the effect of Ar + energy implantation on the strain propagation in AlGaN

In this work, high quality AlGaN layers, grown by metal organic chemical vapour deposition, on a commercial c-sapphire substrate, were implanted at a fluence of 1 × 10 14 A r + ⋅ c m − 2 . Implantation was performed for energies between 25 and 250 keV to explore the strain field created with increasing penetration of the implanted ions. Perpendicular to the sample surface deformation was determined through simulations of the 2 θ − ω scans of the allowed (0002), (0004) and (0006) AlGaN reflections. According to the simulations, the peak attributed to the implanted region is well defined using a small number of layers with specific thickness, deformation, and static Debye–Waller factors. Although similar ion end of range, calculated via Monte Carlo simulations of ions in matter, of around 240–250 nm for 200 keV implanted normal to the sample surface and 250 keV at 38°, the strain distribution in depth turns out quite different in these samples. According to dynamical theory of x-ray diffraction simulations, the argon ions penetrate deeper on the former, which might be related to channeling effects, while maximum damage is observed in the latter. Damage accumulation is suggested to be a complex mechanism, where damage maximum and damage extension play equivalent important roles.