Recent investigation of 4H-SiC PiN diodes has revealed that they degrade during long-term forward-biased operation of the device; this phenomenon was found to correlate with the generation of an increasing density of stacking faults (SF) in the active region of the device. In this paper, a partial dislocation half loop, bounding a triangular stacking fault generated during forward biasing of a PiN diode, has been investigated by transmission electron microscopy (TEM). The triangular stacking fault is bound on two sides by a partial dislocation half loop and on the third side by a surface (or interfacial) step. The two segments of the half-loop are 30degrees partial dislocations, lying along two different < 11 (2) over bar0 > Peierls valleys on the (0001) basal plane, and have the same Burgers vector of the type (1)/(3) < 1 (1) over bar 00 >. Using the technique of large angle convergent beam electron diffraction (LACBED), the core nature of these dislocation segments has been determined. The two segments, each lying along a different < 11 (2) over bar0 > direction, have different cores; one has a core of carbon atoms while the other has a core of silicon atoms.