On the Origin of Diamond Plates Deposited at Low Temperature

Abstract

KEYWORDS low temperature diamond deposition, diamond plates, LA MW PE CVD The crucial requirement for diamond growth at low temperatures, enabling a wide range of new applications, is a high plasma density at a low gas pressure, which leads to a low thermal load onto sensitive substrate materials. While these conditions are not within reach for resonance cavity plasma systems, linear antenna microwave delivery systems allow the deposition of high quality diamond films at temperatures around 400°C and at pressures below 1 mbar. In this work the co-deposition of high quality plates and octahedral diamond grains in nanocrystalline films is reported. In contrast to previous reports claiming the need of high temperatures (T ≥ 850 °C), low temperatures (320 °C ≤ T ≤ 410 °C) were sufficient to deposit diamond plate structures. Cross-sectional high resolution transmission electron microscopy studies show that these plates are faulty cubic diamond terminated by large {111} surface facets with very little sp 2 bonded carbon in the grain boundaries. Raman and electron energy loss spectroscopy confirm a high diamond quality, above 93 % sp 3 carbon content. Three potential mechanisms, that can account for the initial development of the observed plates rich with stacking faults, and are based on the presence of impurities, are proposed.

Linear antenna microwave chemical vapour deposition of diamond films on long-period fiber gratings for bio-sensing applications

“…The grown films exhibit homogeneous morphology without any evident preferential texture. The octahedral and plate-like diamond grains dominate the film because the deposition took place at low temperature, as reported previously in [29]. Both the plates and the octahedral grains are faceted, revealed their crystalline nature.…”

Great Variety of Man-Made Porous Diamond Structures: Pulsed Microwave Cold Plasma System with a Linear Antenna Arrangement

“…This is in contrast to the block-stone growth model. 37 This unique bottom-up porous diamond growth, observed only when there is a high CO 2 content in the LAMWP system, is minimally affected by the deposition temperature. In this sense, the LAMWP system is suitable for porous diamond growth on temperature-sensitive substrates over a large area.…”

“…proposed a model in which the formation of diamond plates is related to silicon atoms, i.e., “impurity traces” coming from the quartz tubes. Here, Si atoms were involved as a catalyst that either blocks diamond layer growth or enhances the selective etching of {111} diamond facets (for details, see ref (37)). Drijkoningen et al reported that once the diamond crystals enlarged their size enough, the plate growth collapsed and microcrystalline grains dominated the surface morphology of the sample.…”

Low Temperature Synthesis of Lithium-Doped Nanocrystalline Diamond Films with Enhanced Field Electron Emission Properties

“…The key necessity for diamond growth at low temperature is a high-plasma density at a low-gas pressure, which leads to a low thermal loading of the substrate materials. While these conditions are not within reach for resonance cavity plasma systems, the LA CVD system enables the deposition of high-quality diamond films on larger areas with satisfactory growth rates, while allowing an easy up-scaling and industrial implementation [ 17 ]. To facilitate the comparison, NCD films were also grown on Si-substrates covered with a similar Cr-coating, using the same deposition parameters.…”