Approaches to influence the microstructure and the properties of Al–Cr–O layers synthesized by cathodic arc evaporation

Al–Cr–O layers were synthesized by reactive cathodic arc evaporation utilizing DC as well as pulsed operation of the arc sources. The observed increase of the substrate ion current in the pulsed mode is attributed to the increased ionization of the oxygen reactive gas. The influence of the substrate ion current and the oxygen flow on the microstructure of the layers has been investigated. A strong influence of the oxygen gas flow on morphology and crystal structure has been observed. The increased substrate ion current in the pulsed mode has seemingly no influence on layer morphology at low bias voltages, but influences the nucleation behavior of the layer. The appearance of a multi-layer structure in the synthesized layers utilizing a single composite target has been ascribed to partial ion splitting of the target constituents in the curvilinear arc discharge.