Temperature Dependence of the Band-Edge Injection Electroluminescence of 4H-SiC pn Structure

We present the injection electroluminescence spectra in the temperature range 290-800 K of 4H-SiC pn structure, which was formed by implantation of Al+ ions in low-doped n-type conductivity 4H-SiC epitaxial layer. The dominant emission band of injection electroluminescence (IEL) spectrum at room temperature was observed in the blue-green region; as the temperature is raised, the blue-green band is quenched, while UV band (near band-edge) IEL become dominant. The peak parameters of UV band at room temperature are: hmax  3.17 eV, full width at half maximum w  90 meV. The UV peak shifted in the long-wave direction with increasing temperature; the hmax (T) dependence was linear with the slope of -2.3∙10-4 eV/K. Both the IEL intensity of the UV peak at hmax and band width w increased upon heating. The w(T) dependence was linear with the slope of 2.9∙10-4 eV/K; intensity increased with the activation energy of 100-150 meV. The UV IEL band can be considered more probable to the band-band recombination and edge IEL increasing with rising temperature can be explained by the nonequilibrium charge carriers lifetime increasing.