Heteroepitaxy of Ni-Based Alloys on Diamond

Growth of perfect heteroepitaxial metal layers on diamond can extend applications of diamond in microelectronics and open new areas for its use in devices with unique electrical properties for operations at elevated temperatures and in harsh environments. This work implements the heteroepitaxy of Ni-based alloys on single-crystal diamond and demonstrates a significant improvement of heteroepitaxial quality. The crystal lattices of the Ni-Cu, Ni-Cu-Cr, and Ni-W alloys used for heteroepitaxy have parameters close to those of diamond, a = 3.567 angstrom. Heteroepitaxy was achieved on all diamond faces; the best results were obtained on the {100} faces. According to X-ray diffraction data, the lattice parameters of the heteroepitaxial films and diamond in the epitaxial plane differ by no more than 0.5%. The heteroepitaxial quality of the films is characterized by values of 0.3-0.4 degrees of the full widths at half-maximum of the X-ray rocking curve. Structural perfection of the NiCu epitaxial layers becomes better when their lattice parameters match with the diamond ones at the growth temperature. Owing to a good epitaxial matching, epitaxial crystallites of the Ni-based alloys demonstrate good wetting of diamond, despite the absence of chemical adsorption and a metal carbide layer.