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)

Publisher: Springer

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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 ω_LO 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

Keywords: 4H-SIC; FOURIER TRANSFORM INFRARED REFLECTION (FTIR); LONGITUDINAL-OPTICAL (LO) PHONON-PLASMON COUPLED M; FREE-CARRIER CONCENTRATION (FCC)

Document Type: Research article

Publication date: 2005-04-01