The interaction of atomic oxygen with thin copper films

Abstract

A source of thermal, ground-state atomic oxygen has been used to expose thin copper films at a flux of 1.4×1017 atoms/cm2 s for times up to 50 min for each of five temperatures between 140 and 200 °C. Rutherford backscattering spectroscopy was used to characterize the oxide formed during exposure. The observations are consistent with the oxide phase Cu2O. The time dependence and the temperature dependence of the oxide layer thickness can be described using oxide film growth theory based on rate limitation by diffusion. Within the time and temperature ranges of this study, the growth of the oxide layers is well described by the equation L(T,t)=3.6×108 exp(−1.1/2kBT)t12, where L, T, and t are measured in angstroms, degrees Kelvin, and minutes, respectively. The deduced activation energy is 1.10±0.15 eV, with the attendant oxidation rate being greater than that for the corresponding reaction in molecular oxygen.

Preparation of large-scale cupric oxide nanowires by thermal evaporation method

“…SEM observation shows that there are two layers about several microns in thickness on the copper foil surface, judging from XRD analysis, the bottom layer consists of Cu 2 O and the top layer is CuO. The result is corresponding to the previous studies on the oxidation process of copper [21][22][23]. When copper foil is heated in O 2 , it is oxidized to form Cu 2 O at first, and CuO is formed through a second step of oxidation of Cu 2 O.…”

“…Considered with the XRD result of the bottom side, there is a possibility that the nanowires are in CuO phase, which grow on the surface of a CuO/Cu 2 O/Cu multilayer structure. The chemical reactions to synthesize the CuO nanowires can be described by the following two steps[21][22][23]:…”

Degradation of Cu nanowires in a low-reactive plasma environment

“…In the study, the authors observed that the Cu thin films (Cu 2 O) had a higher reactivity with monoatomic O than with molecular O (i.e. O 2 ), even in low-pressure conditions (0.0013 mbar) 7 . This was similarly investigated by Kennedy and Friesen 9 whose concluded that the growth of Cu films via sputtering processes can be affected by the O partial pressure and that the presence of a low-content O atmosphere can lead to adsorption, which upon segregation at the surface may initiate oxide layer growth.…”

“…A recent application of nanomaterials involves miniaturisation of electronic circuits and devices which has potential to revolutionise the electronics industry [7][8][9][10][11][12] , not only by extending the validity of Moore's law, but exceeding the scientific vision beyond it [13][14][15] . In this context, the search for reliable synthesis and processing routes for nanomaterials remains a significant challenge for academia and technology companies: for example, the ion-beam-induced processing doping of semiconductor nanowires was shown to severely degrade them via mechanisms known as ion-induced bending 16,17 .…”

“…Although the low-or high-reactive plasma degradation of NWs is largely sub-notified in the literature, several authors reported degradation effects of plasma on metallic thin films. Gibson et al 7 observed the effects of a simulated plasma environment (similarly to that found in low earth orbit) on a Cu thin films by analysing interaction of monoatomic O with their surfaces. In the study, the authors observed that the Cu thin films (Cu 2 O) had a higher reactivity with monoatomic O than with molecular O (i.e.…”