Study on the lateral growth of the diamond in the substrate holder and the effect of temperature gradient on the large-area diamond surface morphology

The study of the distance between the substrate edge and the substrate holder cavity edge on the growth quality was further carried out. The results showed that the substrate edge quality decreased with the increase in the distance from the substrate edge to the substrate holder cavity edge, and the lateral growth rate significantly increased. Therefore, a three-step growth method was proposed. After 68 h of growth, the substrate size grew from 3.57 mm x 3.63 mm x 1.01 mm to 6.13 mm x 6.04 mm x 2.52 mm, but at the end of the third step, the quality and the morphology of the substrate became poor. Two experiments were carried out to verify the influence of eccentric placement and the substrate holder cavity edge on the substrate morphology. The results showed that the influence of the substrate holder cavity edge on the substrate edge quality was more significant than that of eccentric placement. Because of the lateral growth, the substrate edge will inevitably be closer to the cavity edge during the growth, and its temperature gradient will increase. Therefore, an improved substrate holder was designed, and the simulation results showed that the new substrate holder could effectively guarantee the uniformity of the temperature gradient on the large-scale substrate surface.