Infrared spectroscopic ellipsometry is used to study the influence of strain and composition on the transverse-optical phonon mode of E1 symmetry in hexagonal Al1-xInxN films for 0.12≤x ≤0.21. The 0.1-0.2-μm thick films were grown on slightly compressively strained hexagonal GaN buffer layers, or directly on  sapphire by metalorganic vapor phase epitaxy. The Al1-xInxN E1(TO) phonon shows a one-mode behavior in contrast to recent theoretical predictions [H. Grille, C. Schnittler, and F. Bechstedt, Phys. Rev. B 61, 6091 (2000)]. Films grown on GaN reveal the influence of strain on the phonon mode frequencies due to pseudomorphic film growth. Al1-xInxN deposited directly on sapphire possesses phonon modes which indicate fully relaxed film growth.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)