Investigation of surface and interface phonon polariton in nitrogen-implanted GaN epi-layers

In recent decades, gallium nitride (GaN) has garnered significant attention from researchers due to its diverse applications in microelectronics and optoelectronic devices. In this manuscript, using infrared attenuated total reflectance (IR-ATR) spectroscopy, the surface phonon polariton (SPP) and interface phonon polariton modes of unimplanted, N+-ion-implanted, and post-annealed GaN epitaxial layers have been investigated and analyzed at various doses experimentally and theoretically. The position of the SPP mode and its broadening as the increase in implantation doses and post-annealing treatment in the GaN samples are discussed. Shifting in the SPP absorption dip from (698.3–692.7 cm−1) for the unimplanted to implanted dose is correlated with damping factor (ranging from 10 to 80 cm−1) using theoretical reflectance by the model based on damped oscillations between the Ga and N atoms. Unimplanted, implanted, and post-annealed GaN samples Raman spectroscopy and optical absorption have been employed to extract the optical parameters. Optical parameters extracted from Raman spectroscopy and UV–visible spectroscopy such as tensile strain, phonon lifetime, and band-edge absorption have been correlated with the position and broadening of the SPP, as well as the damping factor on unimplanted, N+ ion-implanted, and post-annealed GaN specimens. Notably, the experimental IR-ATR data showed strong agreement with the theoretically modeled results.