Temperature dependence of crystalline SiGe growth on sapphire (0001) substrates by sputtering

The temperature dependence of the film morphology and twin structure of SiGe thin films sputtered on sapphire (0001) substrates was characterized using Scanning Electron Microscopy (SEM), with Electron Backscatter Diffraction (EBSD) and cross-sectional Transmission Electron Microscopy (TEM) analysis. It was observed that the type of growth twin formed was different at the two temperatures evaluated, 820 °C and 890 °C. At the lower temperature, two crystallographic variants rotated from each other by 60° nucleated and propagated (growth twinning). At the higher temperature, the growth twin was suppressed after continuous films were formed and micro-twin lamellae were formed. Consequently, the volume of twins was reduced with the increase in growth temperature and the crystalline morphology was improved.

► Characterized the film morphology and twin structure of SiGe on sapphire (0001). ► Different types of growth twin formed at 820 °C and 890 °C. ► At 820 °C, huge twin-related islands were formed with no continuous film. ► At 890 °C, the growth twin was suppressed after continuous films were formed. ► Reduced volume of twins to 0.1% at 890 °C and improved morphology.