Bias-enhanced nucleation of diamond on iridium: A comprehensive study of the first stages by sequential surface analysis

The chemical evolution of the iridium surface along the successive steps of BEN was investigated using electron spectroscopy techniques (XPS, AES). To this end, a sequential study was carried out in an UHV analysis chamber connected to a MPCVD reactor. First, experimental results were obtained on iridium surfaces exposed to a methane plasma without bias. They show a sp 2 carbon layer formation on iridium, probably due to the segregation during cooling of carbon solubilized at high temperature in iridium. In this scenario, the iridium surface would be uncovered by carbon as BEN starts. Then, the consequences of BEN were observed: (i) formation of a thicker carbon layer at the iridium surface due to carbon segregation and sub-implantation (ii) chemical modification of iridium neighboring within the first nanometers; (iii) diamond nucleation. ► In this study, we examine iridium surface evolution by spectroscopic analysis. ► Hydrogen methane plasma exposure leads to carbon dissolution into iridium matrix. ► Bias enhanced nucleation enhanced the quantity of carbon. ► Surface analysis reveals several mechanisms competing during BEN on iridium.