Fig. 1. Schematics of reactor and substrate holders. (a) MPCVD reactor and semi-open substrate of Mo; (b) different types of substrate holders

Fig. 2. Spectra of seed crystals at different Δh values. (a) Optical emission spectra of CH₄/H₂ plasma; (b)--(c) C₂ (516.08 nm) and H_β (486.25 nm) intensity distribution along the radial direction of substrate; (d) emission intensity ratio of C₂ (516.08 nm) to H_β (486.25 nm) along the radial direction of substrate

Fig. 3. Optical images of single-crystal diamond (~3 mm×3 mm HPHT seed crystals) grown in the semi-open holder with different protrusion heights. (a) 0.2 mm; (b) 0.3 mm; (c) 0.4 mm; (d) 0.5 mm; (e) 0.6 mm; (f) 0.8 mm

Fig. 4. Optical images of single-crystal diamond grown in the semi-open holder with different protrusion heights. (a) 0.2 mm; (b) 0.3 mm; (c) 0.4 mm; (d) 0.5 mm; (e) 0.6 mm; (f) 0.8 mm

Fig. 5. Optical images of sample e, when Δh=0.6 mm

Fig. 6. Height distribution images and cross-sectional profiles of single-crystal diamond (~3 mm×3 mm HPHT seeds) measured by scanning white light interferometric microscopy with a scanning dimension of 928 μm×696 μm, the SCD seed grown in a semi-open holder with Δh=0.6 mm

Fig. 7. As-grown CVD single-crystal diamond after lateral outward growth. (a) Image of single-crystal diamond (3.25 mm×3.30 mm HPHT seed); (b) side view image of single-crystal diamond; (c) Raman spectra in the central region of the top surface, the edge expansion area of top surface and the lateral surface; (d) FTIR diagram of HPHT single-crystal diamond seed and CVD epitaxial lateral layer (Δh=0.6 mm)