The Surface Oxidation Kinetics of Cu(100) and (110) Thin Films Visualised by In situ UHV-TEM

In situ microscopy provides dynamic information about nucleation, growth and coalescence of islands in real time. We utilised in situ ultra-high vacuum transmission electron microscopy to gain fundamental insights into the oxidation of Cu films. A semiquantitative model, where oxygen surface diffusion is the dominant mechanism for transport, nucleation and growth of the copper oxide, describes both the Cu(100) and Cu(110) initial oxidation behaviour. Oxide island formation was observed even at atmospheric pressures, where we speculate that nucleation and coalescence of oxide islands explains the self-limiting behaviour of Cu passivation and apply this concept to explain the different passivation film thickness for Cu(100) and Cu(110).