Temperature-dependent Raman spectroscopic studies of AlN epi-films by metal-organic chemical vapor deposition

Temperature-dependent Raman scattering measurements are performed over the range of 80–810 K, and an investigation is conducted on two AlN epitaxial films (1.8 and 3.7 μm) grown on sapphire by metal-organic chemical vapor deposition. Simulations are carried out for the AlN phonon modes of E2(high) by the space correlation model and A1(LO) by longitudinal optical phonon and plasma coupling over the range of 80–810 K. Temperature-dependent values of carrier concentration, electron mobility, crystalline perfection degrees, and biaxial stress along the film growth direction are acquired. Their graphical variations and formulized polynomial descriptions are presented. Different from traditional Hall and C–V electrical measurements, our method of using an optical technique for determining high-temperature carrier concentration and mobility along the epitaxial direction nondestructively may provide a useful method for the research and development of AlN and other semiconductors.