Project R-1506

Metal based nucleation interlayers for nanocrystalline diamond growth (Research)

Nanocrystalline diamond (NCD) films have attracted substantial interest due to their wide range of applications such as platforms in nano/micro-electromechanical systems (N/MEMS), based on diamond┌s excellent mechanical and tribological properties, or SOD (silicon on diamond) as an alternative to SOI (silicon on insulator), where the diamond replaces SiO2, providing good heat dissipation due to its large thermal conductance, together with attractive dielectric properties. For all these kinds of applications, large surface areas have to be covered. Critical properties of the diamond layer are phase purity, an extremely uniform, submicron film thickness, a concurrent low surface roughness and a uniform grain size distribution across the film surface. These requirements are achieved by the growth of thin coalesced films, consisting of small, closely packed grains. To this end, a high nucleation density is required. In the current project, we will explore new approaches to diamond nuclei generation in order to be able to grow uniform nanocrystalline diamond layers on different (foreign) substrates: the strategy will be to in situ generate diamond nuclei in a composite interlayer containing carbon and a carbide-forming metal. The project takes an interdisciplinary approach and therefore, will be carried out by intensive cooperation between the groups of Inorganic and Physical Chemistry (M.K. Van Bael & A. Hardy) and Wide Band Gap Materials (K. Haenen) within the Physics department, both in the Institute for Materials Research. The metal based interlayer will be deposited from aqueous solutions, containing selected metal ion complexes (this is the main expertise of the group of M.K. Van Bael and A. Hardy). A high concentration of carbon should be present in this metal based layer, in order to obtain in situ generated diamond nuclei at high density. After the deposition of these new nucleation layers, diamond will be grown with microwave plasma enhanced chemical vapour deposition, the nucleation density will be evaluated and brought in relation with de nucleation and growth mechanism (this is the main expertise of the group of K. Haenen). The combination of the concept of seed generation from carbon within the metal based interlayer, deposited from aqueous precursor solutions is new to the current literature. By this complementary approach, the formation of a dense and nanocrystalline diamond film will become feasible, with one of the main advantages that aqueous solution deposition allows continuous though very thin seed layers to be deposited. This way, long incubation periods for growth can be avoided.

01 January 2009 - 31 January 2012