| Diamond thin films are deposited on silicon wafers by MPECVD process with the presence of methane, argon, and hydrogen gases. The reaction chamber is designed with an internal microwave reaction cavity and a high-pressure pocket for improving deposition conditions. Scanning electron microscopy reveals tetrahedral and cauliflower-shaped crystals for polycrystalline diamond and nanocrystalline diamond films, respectively. Spectroscopy ellipsometer studies indicate that diamond-like carbon (DLC) films are deposited with a thickness of 700 nm. Fourier transform infrared spectroscopy shows C-H stretching in the range from 2800 cm-1 to 3000 cm-1. Nanoindentation is performed on DLC films with an average hardness of 10.98 GPa and an average elastic modulus of 90.32 GPa. The effects of chamber pressure, microwave forward power, and gas mixture on the plasma chemistry are discussed. Substrate temperature has a significant influence on film growth rate, and substrate pretreatment can enhance the quality of diamond films. |
