Final Report Summary - DIAMEMS (Microelectromechanical Systems from Nanocrystalline Diamond) Facilities for the nucleation and Chemical Vapour Deposition (CVD) of diamond have been installed at Cardiff University. Films have been optimized and growth below 100nm thick realized (30nm). Films have been grown at temperatures as low as 400C and the uniformity shown to be better than 5%. Thus, the knowledge of nanocrystalline diamond growth ahs been successfully transferred from the Fraunhofer IAF to Cardiff University. The stress in the films has also been optimized, resulting in wafer bows of less than 10µm over 2”. Thus work package 1 is complete.The Chemical Mechanical Polishing of diamond has been demonstrated and has recently resulted in a high profile publication in Carbon [1]. This paper details the planarization of nanocrystalline diamond to roughness values below 2nm rms over several µm2. A second paper showing how this technique can also be applied to {100} and {111} single crystal diamond is currently under review. Thus work package 2 is complete.The integration of AlN with diamond has been demonstrated by two complementary approaches. The first more conventional approach exploited the low roughness of diamond after planarization to grow c-axis orientated AlN on diamond, which resulted in high frequency SAW devices operating in excess of 15 GHz [2, 3]. These devices were also demonstrated as high precision pressure sensors, capable of application in harsh environments [4]. These results have attracted a very large telecommunications company to invest money in their further development (under non-disclosure), thus they can be said to have had real socioeconomic impact. This work was in collaboration with the Technical University of Madrid and is currently being assessed for industrial deployment.In a second more novel approach, diamond growth has been made possible on AlN by manipulating the zeta potential of the nanodiamond seeds [5]. This approach is a low cost alternative to the approach as it removes the requirement of planarization. High frequency piezoelectric Micro-Electro-Mechanical Systems (MEMS) were demonstrated using this approach, thus satisfying the final deliverables of work packages 3, 4 and 5. In addition to the milestones of the project, the technology developed within these work packages has also been also to develop state of the art MEMS for the study of non-linear dissipation with Boston University [6].We have investigated the electron spin resonance behavior of superconducting nanocrystalline diamond in collaboration with Budapest University of Technology, the University of Vienna, CNRS Grenoble and École Polytechnique Fédérale de Lausanne [7].Very recently, we have demonstrated the potential of combining superconductivity with MEMS in collaboration with Institut Néel [8]. Boron doped nanocrystalline diamond based magneto-motive nano-cantilevers were shown to resonate at 10 MHz under magnetic fields as high as several Tesla. The operation of these devices in the superconducting states is impressive, as high magnetic fields and high frequency currents are usual detrimental to superconductivity. Further work is underway to increase the resonant frequency so that the quantum ground state of the cantilever could be reached at 20mK.In summary, this project has demonstrated the efficacy of nanocrystalline diamond for conventional MEMS, SAW devices as well superconducting nano-resonators. Technologies such as CMP and high frequency SAW filters are expected to have a significant industrial impact, having already attracted interest from several companies. The principal investigator now has a permanent position as a Reader in Experimental Physics at the Cardiff School of Physics and Astronomy. His group comprises of two postdocs and three PhD students. Further information of the group activities and capabilties is available at www.nanodiamond.co.uk.References1. Thomas, E.L.H. et al., Chemical mechanical polishing of thin film diamond. Carbon, 2014. 68(0): p. 473-479.2. Rodriguez-Madrid, J.G. et al., Optimization of AlN thin layers on diamond substrates for high frequency SAW resonators. Materials Letters, 2012. 66(1): p. 339-342.3. Rodriguez-Madrid, J.G. et al., Super-High-Frequency SAW Resonators on AlN/Diamond. Electron Device Letters, IEEE, 2012. 33(4): p. 495-497.4. Rodríguez-Madrid, J.G. et al., High precision pressure sensors based on SAW devices in the GHz range. Sensors and Actuators A: Physical, 2013. 189: p. 364-369.5. Hees, J., et al., Piezoelectric actuated micro-resonators based on the growth of diamond on aluminum nitride thin films. NANOTECHNOLOGY, 2013. 24(2): p. 025601.6. Imboden, M., O. Williams, and P. Mohanty, Nonlinear dissipation in diamond nanoelectromechanical resonators. Applied Physics Letters, 2013. 102(10): p. 103502-4.7. Szirmai, P., et al., Observation of conduction electron spin resonance in boron-doped diamond. Physical Review B, 2013. 87(19): p. 195132.8. Bautze, T., et al., Superconducting nano-mechanical diamond resonators. Carbon, 2014. 72(0): p. 100-105.
