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

•Ultra-nano-crystalline diamond (UNCD) films grown by MP–CVD system.•The hardness of the films is found to be ∼30 GPa and Young’s modulus ∼300 GPa.•The electron field emission, the turn on electric field, ETOE = 11 V/μm.•UNCD could be useful for flexible materials for thin film coating technology. Ultra-nano-crystalline diamond (UNCD) thin films with average thickness ∼200 nm, were grown on n-type mirror polished silicon (100) substrates using microwave plasma enhanced chemical vapour deposition system in different gas (H2 - N2 - Ar - CH4) composition plasma atmospheres at 1200 W (2.45 GHz) and in a pressure of 120 Torr with plasma-temperature ∼475 °C. Raman spectroscopy was used for microstructural study and nano-indentation 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 ∼30 GPa, Young’s modulus ∼300 GPa and induced electron field emission, the turn on electric field, ETOE = 11 V/μm. All results show that the UNCD could be useful for different industrial semiconductor/optoelectronic devices and as flexible materials for thin film coating technology.