Oxidation dynamics of Cu thin film on Si surface by mass analyzed O plus ion implantation and study their electrical and optical properties

In this article, the ion beam-induced oxidation dynamics of copper (Cu) thin film and transport properties of the ion-modified films, deposited on Si substrate by e-beam evaporation, are investigated. Low energy (10 keV) O+ ion bombardment on Cu films at normal incidence leads to the formation of cuprous oxide (Cu2O) and cupric oxide (CuO) phases at different stages of bombardment. The dynamical change of the cuprous oxide (Cu2O) phase to the mixture of Cu2O and CuO phases with increasing ion fluence is observed via X-ray photoelectron spectroscopy (XPS) and grazing incidence X-ray diffraction. Ion implantation leads to a decrease in crystalline size with an increase in ion fluence. The increase of oxygen concentration and the absence of foreign impurities in Cu films at higher ion fluence are also measured by XPS and Energy-Dispersive X-ray spectroscopy. The oxygen concentration reduces from 82 % to 58 % for the cuprous oxide phase, whereas the same increases from 18 % to 42 % for the cupric oxide phase. The optical response due to enhancement of the oxygen atoms in ion-modified Cu thin films investigated using UV-visible spectrophotometer, shows higher absorption in the visible region compared to untreated Cu film. Post-bombardment changes in resistivity of copper oxide films, containing the mixture of two chemical phases, exhibit metallic and semiconducting behavior at temperatures 10-110 K and above 110 K, respectively. Temperature varying (300-350 K) Hall measurements of the oxygen implanted Cu film shows changes in the threshold values of mobility (1.4 to 2.4 cm2/Vs), resistivity (18 x 10-6 -150 x 10-6 ohm-cm) and carrier concentration (2 x 1022 -15 x 1022 cm-3). The potential applications of pure copper oxide films prepared by low-energy ion implantation without thermal treatment are also addressed here.