Ion Beam Synthesis of Diamond-SiC-Heterostructures

Nanocrystals of silicon carbide were synthesized inside natural diamond using high dose silicon implantation. In order to retain the diamond structure, however, implantation was done at 900 °C. The samples were subsequently annealed in an rf-heated furnace at 1500 °C for 10 minutes. X-ray diffraction (XRD), IR absorption spectrometry and high-resolution cross-sectional transmission electron microscopy (HRTEM) are used to investigate formation and structure of SiC nanocrystallites in the implanted diamond. Raman spectroscopy contributed to trace implantation-induced destruction of the diamond. A first characterization of the electrical properties of the implanted and annealed samples is done by four point probe measurements. The results indicate a highly conductive, buried layer inside the diamond. This layer contains cubic SiC nanocrystals, which are perfectly aligned with the diamond lattice. However, when fluence exceeds a critical value of 5.3×1017 Si+cm-2, the diamond is irreversibly damaged and defect conduction type dominates.