Microscale optical spectroscopic probe techniques, mainly micro-Raman scattering (m-RS) and microphotoluminescence (?-PL)
spectroscopy, are employed to study a variety of GaN thin film materials, undoped and Si and Mg doped, grown on c-sapphire substrates by lowpressure
metal-organic chemical vapor deposition. The optical properties and correlated structural features of these epitaxial materials grown
under different conditions are studied. Visible micro-Raman measurements show different mode behaviors under different laser incidence
configurations. Raman line shape analysis through two sets of equations leads to the monitoring of the sample quality and stress, and the optical
determination of electrical properties of GaN films. An approximate 3 cm-1 shift in the E1 (LO) mode frequency is observed across the GaN
film from the sapphire/GaN interface to the GaN surface, indicating the spatial variation of strains along the film growth direction within a few
micrometers thickness range. Combined Raman and PL spectra are obtained under UV excitation, and interesting high-order resonance Raman
features are observed using a sensitive UV-Raman-PL microscope. A new way to characterize the p-type GaN is introduced. These fruitful
results demonstrate the capabilities of ?-RS-PL technology for the research and development of GaN and other materials.
Zhe Chuan Feng,
"Micro-Raman scattering and micro-photoluminescence of GaN thin films grown on sapphire by metalorganic chemical vapor deposition," Optical Engineering 41(8), (1 August 2002). https://doi.org/10.1117/1.1489051
Zhe Chuan Feng, "Micro-Raman scattering and micro-photoluminescence of GaN thin films grown on sapphire by metalorganic chemical vapor deposition," Opt. Eng. 41(8) (1 August 2002)