This paper deals with the light emission, which arises from the passage of a current in the forward direction over a $p-n$-barrier in a transparent ("pure") silicon-carbide crystal. The results differ from previous results obtained on a dark blue (impure) silicon carbide crystal in several respects: The spectral distribution of light emission is found to be independent of current and temperature. Both the efficiency of light emission and the decay constant of light emission increase exponentially with decreasing temperature. This is explained by a nonradiative transition of excited electrons. In a dark blue (impure) silicon carbide crystal, the resistances in series with the $p-n$-barrier were largely eliminated, and light emission at a voltage of the same magnitude as $\frac{h\nu }{e}$, was observed.

• Received 16 May 1952

DOI:https://doi.org/10.1103/PhysRev.89.20