Nanodiamonds are a microengineer’s best friend
Devices are becoming increasingly smaller with enhanced functionality and performance but new applications require endurance under extreme conditions. The EU-funded project 'Nano-diamond building blocks for micro-device applications' (NANODIA) explored the potential of nano-crystalline diamond by addressing issues that are currently impeding their use. Initial experiments aimed at enhancing the uniformity and density of nucleation, the first step in crystallisation. They also worked on promoting the growth of nano-crystalline diamond thin films via seed layers. Scientists demonstrated enhanced nucleation and film growth after deposition of metallic seed layers on mirror-polished silicon. Rapid carbide-forming metals elicited the highest density of nano-diamond crystals resulting in dense, uniform and very smooth nano-crystalline diamond films. Further, enhancement of the seeding step was not related to substrate morphology but rather to substrate surface chemistry and type of diamond nanoparticles. Scientists also studied growth dynamics of nano-diamond and diamond-like carbon films created using different deposition processes. Atomic force microscopy elucidated the evolution of cauliflower-like surface morphology. For the first time ever, the development of these intricate surface patterns were described in terms of fractals seen ubiquitously in living and non-living systems. Finally, researchers investigated the behaviour of nano-diamonds in sliding micro-contacts for industrial application in microsystems with moving mechanical parts. They worked on optimising the full-diamond atomic force microscopy probes recently developed for commercial use. Efforts were focussed on the high-performance boron-doped diamond thin films for the tips. Tests demonstrated that the wear rate increased dramatically with the boron doping level, which was also directly related to softer films and greater nano-indentation. NANODIA provided valuable insight into the creation of nano-crystalline synthetic diamond thin films for application in nano-devices. Project activities established a foundation for use of diamond in micro-devices requiring superior mechanical, chemical and thermal properties.
Keywords
Nano-crystalline, diamond, nucleation, thin films, seed layers, fractals, microscopy probes
