Transmission electron microscopy investigation of dislocations in forward-biased 4H-SiC p–i–n diodes

When a 4H-SiC $\mathrm{p–i–n}$ diode is operated under forward biasing, it rapidly degrades, and the degradation is accompanied by the generation of a high density of stacking faults in the active region of the device. In this letter, the partial dislocations bounding the stacking faults have been investigated by transmission electron microscopy. They are found to be in the form of single leading partial half-loops with a $\frac{1}{3}\text{〈101̄0〉}$ Burgers vector that bound triangular-shaped stacking faults. Two sides of each faulted loop are bound by two partial dislocation segments lying along different $\text{〈12̄10〉}$ directions, while the other edge of the triangular stacking fault is a surface (or interfacial) step. The core nature of the two segments has been determined by the technique of large-angle, convergent-beam electron diffraction, and found to be different: one has a silicon core, while the other has a carbon core.