Structure of stacking faults formed during the forward bias of 4H-SiC p-i-n diodes

Using site-specific plan-view transmission electron microscopy (TEM) and light emission imaging, we have identified stacking faults formed during forward biasing of $\text{4H-}\mathrm{SiC}\mathrm{ p-i-n}$ diodes. These stacking faults (SFs) are bounded by Shockley partial dislocations and are formed by shear strain rather than by the condensation of vacancies or interstitials. Detailed analysis using TEM diffraction contrast experiments reveal SFs with leading carbon-core Shockley partial dislocations as well as with the silicon-core partial dislocations observed in plastic deformation of $\text{4H-}\mathrm{SiC}$ at elevated temperatures. The leading Shockley partials are seen to relieve both tensile and compressive strain during $\mathrm{p-i-n}$ diode operation, suggesting the presence of a complex inhomogeneous strain field in the $\text{4H-}\mathrm{SiC}$ layer.