@article{oai:nitech.repo.nii.ac.jp:00004561,
 author = {Yu, G. and Ishikawa, H. and Umeno, Masayoshi and Egawa, Takashi and Watanabe, J. and Jimbo, Takashi and Soga, Tetsuo},
 issue = {18},
 journal = {APPLIED PHYSICS LETTERS},
 month = {May},
 note = {A method of analysis of spectroscopic ellipsometry (SE) measurement data is proposed for AlxGa1-xN/GaN heterostructures grown on sapphire substrates. The SE data measured at three angles of incidence, 40°, 50°, and 60°, are simultaneously fitted assuming the dielectric function to consist of a Sellmeir dispersion equation and a free-exciton absorption term. The refractive index n and the extinction coefficient k of undoped AlxGa1-xN films are determined in the spectral range of 1.5-4.13 eV of photon energy. The transition energy of the free exciton, which is in excellent agreement with the reported results for GaN in a previous paper, is found to vary from 3.44 to 3.95 eV when the composition x varies from 0 to 0.151. The refractive index n of AlxGa1-xN has also been compared with those reported results., application/pdf},
 pages = {2202--2204},
 title = {Optical properties of AlxGa1-xN/GaN heterostructures on sapphire by spectroscopic ellipsometry},
 volume = {72},
 year = {1998}
}