Lattice structure of a freestanding nitrogen doped large single crystal diamond plate fabricated using the lift-off process: X-ray diffraction studies

Lattice structures of freestanding, large (~ 9 × 9 mm) nitrogen doped single crystal (SC) diamond plates were investigated mainly by X-ray diffraction including a reciprocal space mapping (RSM) method. After a plasma-chemical-vapor-deposited thick homoepitaxial diamond film was grown at a high-speed on type-Ib (001) diamond, a SC freestanding diamond plate was fabricated by separation of the substrate from the film by a lift-off process using high-energy ion implantation. Due to the use of the lift-off process, there is a thin (~ 1.6 μm in thickness) residual diamond substrate on the back-face of the freestanding plate. It was found that only in the case of the X-ray incidence on the back-face, the RSM around (113) diffraction pattern displayed a long streaky pattern along the [001] direction. This indicates a gradual lattice expansion only along the growth direction. The maximum value of the lattice expansion was approximately + 0.7%. Such a lattice expansion probably occurs around the interface between the thin residual substrate and the film.

► Nitrogen doped large single crystal CVD diamond plates were fabricated using lift-off. ► RSM showed a streaky pattern indicating a gradual lattice expansion only along the growth direction. ► This pattern observed only on the back-face with a residual thin diamond substrate. ► The maximum value of the lattice expansion estimated is approximately +0.7 %. ► Such a lattice expansion seems to presents around the interface.