The partial dislocations that border triangle or parallelogram-shaped stacking faults formed during the degradation of p-n diodes fabricated on 4H-SiC wafers were determined by transmission X-ray topography to be dislocation loops of Burgers vector 1/3<101¯0>, the Shockley partial type, consistent with previously reported TEM results. Some were separated from axial screw dislocations also present in the sample, indicating that the axial dislocations were not involved in the loops' nucleation, while others were seen to have interacted during their growth with the axial screw dislocations, distorting their shapes from those of ideal parallelograms. © 2003 Elsevier Science B.V. All rights reserved.