Formation of I1 Shockley stacking faults by recombination-enhanced defect glide in 4HSiC p-i-n diodes subject to high forward current stress is studied in diodes on both c-oriented and aoriented substrates. The forward voltage increases during stressing for both orientations, accompanied by nucleation and expansion of faults visible in electroluminescence (EL) imaging. Low temperature photoluminescence (PL) measurements on degraded diodes of both orientations reveal the same set of exciton peaks, confirming that the electronic structure of the faults is the same in both cases. The spectroscopic data are compared to self-consistent solutions of the Schrödinger and Poisson equations including polarization charge. Dislocations nucleating the faults are bright in EL images but dark in electron beam-induced current (EBIC) imaging, confirming that they are sites of enhanced radiative recombination.