The surface hybridization of diamond with vertical graphene: a new route to diamond electronics

Abstract

Herein a method is proposed for engineering the electronic properties (including the band structure) of diamond via surface hybridization with graphene. Graphene layers (5-50 nm in thickness) were grown vertically onto a polished < 110 > textured polycrystalline diamond plate (1 x 1 cm(2)) (vGr-diamond) at similar to 1300 degrees C via hydrogen plasma etching in a chemical vapor deposition (CVD) chamber. Due to the crystallographic relationship, the graphene layers embed at an angle of 30 degrees to the diamond surface comprising the (110) planes. The epitaxial relationship is demonstrated via low angle X-ray diffraction (XRD), the XRD rocking curve, Raman and scanning electron microscopy. With hybridization, the diamond sample reveals a strong photoluminescent (PL) signal at similar to 2.78 eV (similar to 450 nm). The peak was assigned to the `interface defects' of the vGr-diamond hybrid structure, which are a type of 'surface defect' of the CVD diamond that generates a peak at similar to 2.69 eV. The blue shift (similar to 90 meV) of the interface defects is due to the compressive strain of similar to 3% applied to the interface atoms. Simulations indicate that the hybrid structures possess a finite band gap of 1.85-0.25 eV, which decreases upon increasing the thickness of the graphene layers to similar to 1.4 nm. The appearance of a small band gap was attributed to the compressive strain. These findings may provide a route for diamond to become a platform for next generation and extreme electronic devices.