Properties of Cr$_{2}$AlC MAX phase thin films prepared by reactive magnetron sputtering

M$_{n+ 1}$AX$_{n}$ (MAX) phases, where $n$ is 1, 2, and 3, M is an early transition metal, A is an A-group element, and X is either C or N, are ternary carbides with unique properties such as low density, easy machinability, and good oxidation resistance. The MAX phase Cr$_{2}$AlC is of particular interest for industrial applications to its excellent high-temperature oxidation resistance and relatively low synthesis temperature. We prepared Cr$_{2}$AlC thin films on c-axis oriented single crystal Al$_{2}$O$_{3}$, glassy carbon and Si thermal oxide substrates using reactive magnetron sputtering as precursor materials for carbide-derived carbon (CDC) films for ``on-chip'' supercapacitors. Film deposition was optimized using elemental composition data obtained by WDXRF. Optimized films were characterized using XRD and scanning electron microscopy. It was found that textured Cr$_{2}$AlC films only form when the composition was Al-rich allowing the formation of a Cr$_{5}$Al$_{8}$ interfacial layer. As film composition was optimized, the interfacial layer did not form but the XRD peaks associated with the Cr$_{2}$AlC also decreased in magnitude. Extremely high-textured films were grown when a thin buffer layer of CrAl$_{2}$ was deposited on the substrate before depositing the Cr$_{2}$AlC films. This result suggests that Cr$_{2}$AlC films may not be ideal for CDC applications since the films may ``lift-off'' during conversion due to the existence of the naturally occurring buffer-layer.