Nitrogen doping of cubic SiC increases the optical absorption in two regions. The free-carrier intraband absorption has a wavelength dependence of ${\lambda }^{2.8}$. An additional narrow band near 3.1 eV is shown to be the direct interband transition from the $X_{1c}$ conduction band to the higher $X_{3c}$ band. The relationship to Biedermann's work on other SiC polytypes is indicated.

• Received 16 April 1969

DOI:https://doi.org/10.1103/PhysRev.186.775