Evolution mechanism of (100) diamond etch pits and dislocations

Single crystal diamond shows great potential for electronic devices, but dislocations and other structural defects remain common, severely limiting device performance. Here, we study the evolution of dislocation-related etch pits on (100) monocrystalline diamond surfaces using O/H plasma etching, which preferentially attacks weak chemical bonds around defects. Femtosecond laser marking enables precise relocation of the same microscopic region before and after homoepitaxial growth. By combining sequential atomic force microscopy (AFM) depth profiling with confocal Raman stress imaging, we track the propagation behavior of threading dislocations. Quantitative analysis of etch-pit depth evolution and Raman peak-shift distributions reveals that the stress field associated with a [001] edge dislocation propagates upward from approximately 20 µm below the substrate surface. At a depth of ∼10 µm above the substrate interface, the stress-field distribution exhibits a characteristic branching signature, suggestive of a transition from a single edge-type toward two mixed-type dislocation features. These dislocation trajectories continue into the CVD overgrowth layer. The proposed propagation pathway is a phenomenological model supported by consistent AFM and Raman data; direct crystallographic verification (e.g., TEM) remains for future work. This study demonstrates that the correlative etching-Raman protocol provides complementary insights into the three-dimensional propagation of dislocations in diamond.