|M.Sc Student||Fuchs Orly|
|Subject||Study of the Primary Formation Mechanism of Nano Diamond|
|Department||Department of Chemistry||Supervisor||Professor Alon Hoffman|
In this work we have deposited, characterized and investigated the primary formation mechanism of nano crystalline diamond films deposited by Direct Current Glow Discharge (DC GD) technique on different substrates. By this method film growth occurs by a subsurface implantation process of energetic carbon species without any pretreatment. On silicon substrates, it was previously found, that the nano-diamond film grows onto an oriented graphitic layer of ~300 nm thickness after a deposition time of ~30 minutes. The aim of this research is to answer the question whether different substrates promote the appearance of the nano diamond film. The deposition study was performed on two main substrates: Crystalline silicon and poly-crystalline diamond film that was deposited by Hot Filament (HF) Chemical Vapor Deposition (CVD) with a micron thickness.
The analysis of the Surface composition, structure and morphology of the films were preformed by High Resolution Scanning Electron Microscopy (HR-SEM), Electron Energy Loss Spectroscopy (EELS), Secondary Ion Mass Spectroscopy (SIMS) and Raman technique. Our results indicate that the nano-diamond film is formed on silicon substrate without pre-treatment only after 30 minutes of deposition. Different treatments to the silicon substrate like mechanical abrasion of the substrate by ultrasonic treatment in slurry consisting of a mixture of small diamond particles (< 0.25 micron) and larger metal particles (40-100 micron) did not show accelerated nano-diamond film deposition. However, only 1-2 minutes of deposition on a poly-crystalline diamond substrate are sufficient to obtain the 1150 cm-1 RAMAN peak that characterizes the formation of the nano diamond film. Our results show that in this case the nano-diamond film growth directly onto the microcrystalline diamond substrate. The findings of this work support the assumption that nano-diamond film is deposited faster on poly crystalline diamond substrate and by that we can support the proposed model of sub-plantation of nano diamond film formation.