Microstructure and electronic properties of ultra-nano-crystalline-diamond thin films

Ultra-nano-crystalline diamond (UNCD) thin films with average thickness similar to 200 nm, were grown on n-type mirror polished silicon (100) substrates using microwave plasma enhanced chemical vapour deposition system in different gas (H-2 - N-2 - Ar - CH4) composition plasma atmospheres at 1200 W (2.45 GHz) and in a pressure of 120 Torr with plasma-temperature similar to 475 degrees C. Raman spectroscopy was used for microstructural study and nanoindentation was used for Hardness/Young's modulus study; whereas X-ray absorption near edge structure, X-ray photoelectron and ultraviolet photoemission spectroscopies were used for electronic structure of UNCD thin films. The hardness of the films is found to be similar to 30 GPa, Young's modulus similar to 300 GPa and induced electron field emission, the turn on electric field, E-TOE = 11 V/mu m. All results show that the UNCD could be useful for different industrial semiconductor/optoelectronic devices and as flexible materials for thin film coating technology.