Investigation of Longitudinal-Optical Phonon-Plasmon Coupled Modes in SiC Epitaxial Film Using Fourier Transform Infrared Reflection
Authors: Sunkari, Swapna; Mazzola, M.S.; Mazzola, J.P.; Das, Hrishikesh; Wyatt, J.L.
Source: Journal of Electronic Materials, Volume 34, Number 4, April 2005 , pp. 320-323(4)
Abstract:Room-temperature Fourier transform infrared reflection (FTIR) spectroscopy was carried out on heavily and lightly doped 4H-SiC films grown by chemical vapor deposition on conducting, n-type (nitrogen) doped substrates. A modelbased curve fit of the experimentally observed reflectance spectra from these samples is performed using a dielectric function that accounts for the phononphoton coupling and plasmon-photon coupling. The value of the longitudinaloptical (LO) phonon frequency estimated from the reflectance spectrum in the range 600-1,200 cm−1 is observed to increase in direct correlation with the electron free-carrier concentration (FCC). This shift reflects phonon-plasmon coupled modes. The shift from the undisturbed ωLO observed, for example, in semi-insulating SiC is exploited to improve the model-based estimation of epi parameters such as thickness and doping in cases where the free-carrier concentration is less than about 2 × 1018 cm−3
Document Type: Research article
Publication date: 2005-04-01