Why is it difficult to synthesize CVD Diamond?
CVD Diamond consists – like coal or graphite – of carbon. The main difference is the arrangement of the carbon atoms in the material (i.e. in the crystal lattice). Unfortunately, graphite is the more stable carbon allotype (form) and therefore diamond is very rare in nature. To convert graphite into diamond high pressure and high temperatures (HPHT) must be applied. Under those conditions, the diamond becomes the more stable carbon allotype. This is the basis of the HPHT growth technique developed in the 1950ties. The possibility to deposit diamond from the gas phase (CVD) has been discovered later in the 1970/1980ties. For diamond CVD a carbon-containing gas is decomposed and the carbon atoms are deposited on a surface. By proper conditions, the growth of diamond crystals can be enhanced and the growth of graphite is suppressed.