One-step growth of a nearly 2 mm thick CVD single crystal diamond with an enlarged surface by optimizing the substrate holder structure

•A modified pocket substrate holder was designed for mm-sized CVD diamond.•A 1.94 mm CVD diamond with an enlarged surface was realized by one-step growth.•The 1.94 mm CVD diamond has good crystallinity and homogeneity. The pocket substrate holder with its sidewalls perpendicular to the surface is widely used to grow CVD single crystal diamond without polycrystalline diamond rims, but the lateral growth of thick single crystal diamond is usually restricted in a one-step procedure. In this work, a modified pocket substrate holder with slanting sidewalls of the pocket was designed to avoid the growth of polycrystalline diamond rims and reserve the lateral growth space of CVD single crystal diamond, simultaneously. As a result, the growth of a 1.94 mm thick CVD single crystal diamond without polycrystalline diamond rims was realized successfully only by one-step growth for 246 h, and the lateral area gain was 1.31. The FWHM values of the diamond (004) X-ray rocking curve and Raman characteristic peak are 40.3 arcsec and 2.45 cm−1, respectively, indicating the diamond has good crystallinity.