Electroluminescence of porous silicon carbide is achieved in a forward-biased SiC p–i–n junction. A broad green spectral feature centered at ∼510 nm is shown to arise from porous SiC. A large SiC surface area in the vicinity of the junction is created by diamond cutting followed by an electrochemically enhanced hydrogen fluoride etch that produces a layer of porous SiC. Photoluminescence is shown not to be responsible for the green emission. This supports the model of carrier recombination at the porous region via lateral bipolar diffusion of carriers. A lateral bipolar diffusion model is presented in which mobile carriers diffuse laterally from the junction toward the porous SiC surface region driven by a lateral carrier concentration gradient. Lateral bipolar diffusion in conjunction with suitable radiative recombination centers provides a possible pathway to achieve high quantum efficiencies in future SiC p–n homojunction or double heterojunction light-emitting diodes. Competing recombination processes and associated ideality factors in 4H-SiC diodes are also examined.

The influence of microindentation on the electroluminescence of silicon carbide was studied in forward-biased 4H SiC p-i-n junctions. Four spectral regions at approximately 390, 420, 445 and 500 nm initially observed on virgin samples strongly depend, in regard to magnitude, on the condition of the starting die. These spectral regions may be interpreted as arising from either phonon-assisted band-to-band transitions or from defect-related transitions. The same SiC die were then subjected to mechanical damage brought about by a series of closely spaced microindentations directed approximately perpendicular to the c-axis. The spectra taken after a first set and subsequently a second set of microindentations are distinct from the initial spectra in all cases, and differences are interpreted as being due to the modification of existing defects or additional defects being generated mechanically. The influence of microindentation on the ideality factor is measured and discussed. Measured light flux with respect to a standard light source is also shown at each microindentation stage.