Three-Dimensional Nondestructive Characterization of Extrinsic Frank-Type Stacking Faults in 4H-SiC Crystals

The luminescence detection technique is one of the most commonly used NDT techniques for detecting stacking faults in 4H-SiC crystals. Commonly used detection methods, such as photoluminescence (PL) and cathodoluminescence (CL), have a relatively shallow detection depth for 4H-SiC crystals. To overcome these shortcomings, in this study, we used two-photon fluorescence microscopy (2PPL) to qualitatively and quantitatively observe the three-dimensional morphology of Frank-type stacking faults for the first time on 4H-SiC crystals. The comparison reveals that the conventional PL and CL cannot accurately detect the complete morphology of stacking faults due to the limitation of the detection depth, nor can they detect the defects of stacking faults existing at a certain depth inside the crystal. The experimental results show that 2PPL can break through the traditional detection depth limitation, and the detection depth of this experiment reaches 130 μm, which is intuitive and accurate for the three-dimensional qualitative and quantitative characterization of the stacking faults on 4H-SiC crystals. We found errors in confocal PL detection of Z-axis depth during the experiments of confocal PL detection and explained the reasons for the errors. This work also analyzes the spatial growth characteristics of the detected Frankish stacking defects.