Self organised formation of layered structure in co-deposited Al–C thin films

The structure formation of Al–C thin films has been investigated in samples prepared on a-SiO2/Si single crystal substrates by room temperature co-deposition. At higher C content, sequential growth of the Al/Al4C3 microcrystalline composite structure and the metallic Al phase has been found in thick films (0.1–1 μm). This self-organised structure formation resulted in a layered phase structure. The microcrystalline composite structure is the first layer to develop on SiOx substrate and forms a layer of uniform thickness. This is followed by the growth of large polycrystalline Al islands which constitute a discontinuous layer with large surface roughness. At a certain stage of Al island growth the microcrystalline composite phase covers the Al crystal surface and the two processes are repeated. The structures formed at various film thicknesses were investigated by transmission electron microscopy and electron diffraction techniques.