The effect of ion implantation on structural damage in compositionally graded AlGaN layers - O. I. Liubchenko; V. P. Kladko; H. V. Stanchu; T. M. Sabov; V. P. Melnik; S. B. Kryvyi; A. E. Belyaev (Semiconductor Physics, Quantum Electronics and Optoelectronics, 2019)