Stress reduction of (111) homoepitaxial diamond films on nickel-coated substrate

• We synthesized the crack-free (111) homoepitaxial diamond films on Ni-coated diamond.
• The MPCVD process can form the Ni islands in hundreds of nanometers on substrate.
• Ni coating on substrate can reduce the tensile stress in the diamond films.
• Surface cracking on thicker films can be retarded by Ni coating on diamond substrate.

Crack-free (111) homoepitaxial diamond films were grown on Ni-coated diamond substrates by microwave plasma chemical vapor deposition. After diamond deposition, the Ni islands with a size of 50–1000 nm were formed and embedded underneath the diamond films. The tensile stress in the diamond films evaluated with micro-Raman spectroscopy can be significantly reduced with the embedded Ni islands, which allows the growth of ~ 5 μm thick crack-free (111) homoepitaxial diamond films with a good quality, compared with those directly deposited on substrates without coating.