Domain formation in diamond nucleation on iridium

Abstract

Domain formation in epitaxial diamond nucleation on Ir(001) surfaces using the bias-enhanced nucleation (BEN) procedure has been studied. Bright areas of up to several microns lateral size with negligible topographic contrast are observed by scanning electron microscopy (SEM) after ion bombardment. When a growth step is applied after BEN, these domains develop into islands of identical shape consisting of epitaxial diamond with a high local area density of oriented grains. Outside the domains the nucleation density is either orders of magnitude lower or the grains are completely non-oriented. The diamond nuclei or precursors which are formed during the BEN step proved to be very stable: They still yielded oriented diamond islands when the samples were stored in air for 1 year before the growth step. Electron backscatter diffraction (EBSD) patterns taken from inside and outside the domains immediately after BEN did not show any significant difference. This allows the conclusion that the modification of the iridium crystal lattice accompanied with diamond nucleation is either very faint or only restricted to a very thin layer at the surface. Kelvin probe force microscopy (KPFM) measurements indicate a reduced work function within the domains.