HOMOEPITAXIAL DIAMOND FILMS ON DIAMOND ANVILS WITH METALLIC PROBES - THE DIAMOND METAL INTERFACE UP TO 74 GPA/

A (100)-oriented natural type-Ia brilliant-cut diamond anvil with thin zirconium electrical probes sputtered onto the culet was coated with an insulating film of diamond using microwave-plasma-enhanced chemical vapour deposition (MPCVD). The critical issue in this high-pressure s tudy is the quality of the homoepitaxial diamond him and its correlati on with the mechanical strength of the diamond film/metallic probe int erface. We report the first high-pressure study on a homoepitaxial dia mond film and underlying zirconium probes to a pressure of 74 GPa. The metallic probes were observed through a transparent lithium fluoride sample with ruby serving as a pressure sensor. After decompression, Ra man spectroscopy revealed that the homoepitaxial film was free from de formation and delamination despite the presence of some sp(2)-bonded c arbon at the Zr/diamond interface and within the bulk of the him itsel f. The present study demonstrates that the presence of residual defect s and graphitic impurities has no significant effect on high-pressure applications of homoepitaxial diamond films. This opens up new areas o f research with diamond anvil cell devices including those of ohmic he ating and electrical transport measurements at ultra-high pressures.