Impurity Bands and Electroluminescence in SiC p‐n Junctions

A study of the electroluminescence of certain SiC p‐n junctions, between 77°K and 830°K, and over a range of 104 in current density, has been used to verify and to extend a 3‐part model (P−N*−N) of the junctions derived from electrical measurements. The electroluminescence, due to recombination in N*, consists of two parts, which may be called impurity luminescence and intrinsic recombination radiation. At low temperatures (≥200°K) only the former is present. Several effects of impurity banding on the electroluminescence can be predicted, and some of these have now been observed. The most striking of these effects is the ``Fermi‐level emission edge'' in the low‐temperature spectra, an edge which moves to higher energies with increasing current density because of the impurity band injection of electrons. The predominance of impurity band injection at low temperatures excludes the possibility of intrinsic recombination radiation. At higher temperatures, however, electron injection is by way of the conductio...