Infrared dielectric constant of cubic SiC

The real dielectric constant for chemical vapor deposition 3C‐SiC grown on silicon (Si) has been determined at 300 K and at 5 K from an analytic fit to interference fringes in transmission over the spectral range from the near infrared to the submillimeter region. This technique is capable of high accuracy being limited typically by the sample thickness and accuracy with which the thickness is measured. The resulting real dielectric constant is lower than the values usually attributed to this material. We find: at 300 K e 0=9.52 and e ∞=6.38; at 5 K e0=9.28 and e ∞=6.22. In all cases the estimated error is ±0.8%. The observed ratio e0 /e∞ agrees with the Lyddane–Sachs–Teller relation to 0.1% at 300 K and 0.2% at 5 K.