Figure 7
From: Smart-cut-like laser slicing of GaN substrate using its own nitrogen
Multiphoton microscopy PL (365 nm) images of epitaxial layer (upper) and epitaxial layer/substrate interface (lower). (a) Cross-sectional schematic image showing the depth of observation. (b) Sample thinned by 18 µm. The red dashed circle indicates cracks, and the yellow dashed circle indicates holes on the substrate side immediately below the epitaxial layer/substrate interface. The generated dense dislocations (red circle) and voids (yellow circle) are observed in the epitaxial layer above the cracks and holes, respectively. The other dispersed black dots in the epitaxial layer are dislocations that originally existed in the substrate and propagated into the epitaxial layer. (c) Sample thinned by 47 µm. No dislocations are generated. (d) Sample thinned by 77 µm. No dislocations are generated. (e) Sample grown on commercially available epi-ready GaN substrate. No dislocations are generated.
