Analytical TEM study of CVD diamond growth on TiO2 sol-gel layers

作者：Lu Ying Gang^*; Verbeeck Johan; Turner Stuart; Hardy An; Janssens Stoffel D; De Dobbelaere Christopher; Wagner Patrick; Van Bael Marlies K; Haenen Ken; Van Tendeloo Gustaaf

来源：Diamond and Related Materials, 2012, 23: 93-99.

DOI：10.1016/j.diamond.2012.01.022

• Diamond film
• Plasma CVD
• Diffusion
• High resolution electron microscopy

The early growth stages of chemical vapor deposition (CVD) diamond on a sol-gel TiO2 film with buried ultra dispersed diamond seeds (UDD) have been studied. In order to investigate the diamond growth mechanism and understand the role of the TiO2 layer in the growth process, high resolution transmission electron microscopy (HRTEM), energy-filtered TEM and electron energy loss spectroscopy (EELS) techniques were applied to cross sectional diamond film samples. %26lt;br%26gt;We find evidence for the formation of TiC crystallites inside the TiO2 layer at different diamond growth stages. However, there is no evidence that diamond nucleation starts from these crystallites. Carbon diffusion into the TiO2 layer and the chemical bonding state of carbon (sp(2)/sp(3)) were both extensively investigated. We provide evidence that carbon diffuses through the TiO2 layer and that the diamond seeds partially convert to amorphous carbon during growth. This carbon diffusion and diamond to amorphous carbon conversion make the seed areas below the TiO2 layer grow and bend the TiO2 layer upwards to form the nucleation center of the diamond film. In some of the protuberances a core of diamond seed remains, covered by amorphous carbon. It is however unlikely that the remaining seeds are still active during the growth process.

• 出版日期2012-3