TEM investigation of alpha alumina films deposited at low temperature

Alpha-phase aluminum oxide thin films were deposited at 480 °C by AC inverted cylindrical magnetron sputtering on nickel coated transmission electron microscopy (TEM) grids and stainless steel substrates. Several previous studies have demonstrated that an alpha phase was possible at low temperature if a chromium template layer was present. However, here we show that alpha phase is possible without the chromium oxide layer. The presence of alpha phase alumina has been confirmed by TEM. Cross-sectional TEM observations have indicated deposition rates as high as 270 nm/h. This intriguing result is attributed to the unique characteristics of the sputtering system which provides more energetic species at the substrate.