Pulsed plasma deposition of chromium oxide/chromium‐cermet coatings

A novel radio frequency magnetron sputtering method for the deposition of composite films which consist of chromium oxide and chromium (Cr₂O₃/Cr‐cermet) is presented. As an extension to conventional reactive sputtering of a Cr target in an argon and oxygen atmosphere the oxygen flow into the process chamber is switched periodically on and off. This leads to an oscillating oxygen partial pressure during the sputtering process and an alternating deposition of metallic chromium and chromium oxide. In situ x‐ray and ultraviolet photoelectron spectroscopy are used to monitor the oxidation state of chromium at the film surface and to study the chemical interactions between adjacent layers. Ex situ x‐ray diffraction analysis reveals the multilayered and nanocrystalline structure of the deposited films. The overall chromium and chromium oxide concentration is estimated from the optical constants n and k determined by reflectance and transmission measurements in the wavelength range between 400 and 2200 nm.