Characterization of planar-diode bias-treatment in DC-plasma hetero-epitaxial diamond growth on Ir(001)

The effect of bias-treatment (BT) on Ir(001)/MgO(001) substrates in a newly invented planar-diode DC-plasma system has been characterized in-situ and ex-situ by X-ray photoelectron diffraction (XPD), XPS, LEED and SEM. Features of XPD patterns of C 1s core levels were in good agreement with those of three-electrode BT [Diamond Relat. Mater. 13 (2004) 2081], although the degrees of anisotropy of C 1s XPD were smaller. Thicknesses of carbon films estimated from intensity ratios of C 1s/Ir 4d5/2 (or 4f) XPS peaks were about 2 times larger than those of three-electrode BT. LEED patterns showed no diffraction spots after BT. As a result, we conclude that epitaxial diamond crystallites with the size of a few nm or so are embedded in a non-oriented carbon layer. In the cases where no finite anisotropy of C 1s XPD was observed, no epitaxial diamond grains were grown in post-CVD as revealed by ex-situ SEM. Thus, it is concluded that the anisotropy of C 1s XPD can be a useful measure of diamond nucleation by BT on Ir(001) substrates.