LO phonon-overdamped plasmon coupled modes in n-type epitaxial films of β-SiC have been measured in the carrier concentration range from 6.9×1016 to 2×1018 cm−3. The carrier concentrations and damping constants are determined by line-shape fitting of the coupled modes and compared with the values derived from Hall measurements. The concentrations obtained from the two methods agree fairly well. The Faust–Henry coefficient determined from the fitting is 0.35. The line-shape analysis of the coupled mode has shown that the dominant scattering mechanisms in β-SiC are deformation-potential and electro-optic mechanisms.

Raman spectra from p-type GaN have been systematically studied in the hole density range of 5×1016–1×1018 cm−3. Contrary to the case of n-type samples, spectral profiles of the LO-phonon-plasmon coupled mode in p-type show no remarkable change with the hole density. Thus, precise evaluation of electrical transport parameters such as carrier density and mobility from the coupled mode profile is difficult. However, a continuum band has been observed in the low-frequency range of the spectra, becoming intense with the increase of the hole density. This band has been attributed to the inter-valence-band transition of holes, and the intensity can be used as a good measure of the hole density.

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3C-SiC p-n junction diodes are prepared on Si substrates by chemical vapor deposition growth with appropriate impurity doping, and their current-voltage (I-V) and capacitance-voltage (C-V) characteristics are studied. I-V curves show good rectifying characteristics with a value of 3.3 for the ideal factor n and a reverse leakage current less than 10 μA at −5 V. The junction area is approximately 0.8 mm2. The built-in voltage is around 1.4 V by C-V measurements.

Temperature dependencies of Hall mobility of nondoped and nitrogen-doped n-type β-SiC films have been analyzed using a conventional theoretical model. Considering acoustic, polar optical, and piezoelectric lattice scatterings, as well as ionized and neutral impurity scatterings, theoretical calculations well fitted to the experimental results are obtained at 70–1000 K. Contributions of acoustic, polar optical, and piezoelectric scatterings to the whole lattice scattering are 84%, 14%, and 2% at 300 K, respectively. Impurity compensation ratio NA/ND of nondoped films increases from 0.45 to 0.96 with increasing Si/C ratio in the source gases. Nitrogen-doped films show constant compensation ratios of 0.25–0.30 with various doping amounts. These values are different from the previous results obtained by the analysis of temperature dependencies of carrier concentration.