Absorption of Light in Alpha SiC near the Band Edge

The absorption in alpha SiC of photons of energy 2.6 ev to 3.3 ev has been measured at temperatures from 77°K to 717°K. The measurements show that the interband transitions are indirect, requiring the absorption or emission of a phonon of energy 0.09 ev. The minimum energy gap is found to be 2.86 ev at 300°K, and above this temperature $\frac{d{E}_G}{\mathrm{dT}}=-3.3\mathrm{}\times {10}^{-4\mathrm{}}$ ev/degree.