The fabrication and characterisation of Al—Cu thin film alloys obtained using co-deposition geometry from individual Al and Cu sources were addressed. A compositional gradient ranging from 36 to 93 at.% Cu was obtained. The surface microstructure evolved with a strong influence on the Cu content. This was connected to the presence of the Cu(111) in the alloys. The electrical resistivity showed a decrease by almost one order of magnitude in the Cu rich region of the Al—Cu combinatorial library. Al—Cu thin films evaporated from a single source produced a surface compositional gradient of 7 at.%. X-ray photoelectron spectroscopy (XPS) depth profiling revealed an in-depth compositional gradient as well. This behaviour was attributed to the gas phase dynamics of Al and Cu during the thin film formation.