High crystalline quality heteroepitaxial diamond using grid-patterned nucleation and growth on Ir

Abstract

High crystalline quality heteroepitaxial diamond films were successfully formed by using grid-patterned growth on Ir with dc plasma CVD. The crystalline qualities were evaluated by X-ray diffraction, Raman spectroscopy, and etch pit method. Flat {100} diamond films without unepitaxial crystals were formed through epitaxial lateral overgrowth with grid-patterned nucleation region of 100-μm spacing. Omega-rocking curves using X-ray diffraction showed obvious improvement in tilt and twist components for wider grid-spacing. For 100-μm grid spacing, the lowest tilt and twist were 0.064 and 0.043°, respectively. The average dislocation density of 9 × 106 cm−2 for the diamond film grown with grid spacing of 100 μm was the lowest ever in reported values for heteroepitaxial diamond. A correlation between the distribution of crystallinity and dislocation was discussed from the results of etch pit method, Raman mapping and TEM observation. Finally, the crystallinity was compared with single crystal diamonds grown by CVD and HPHT. By using grid-patterned nucleation, the quality of heteroepitaxial diamond on Ir has reached in the range of homoepitaxial diamond film.