Grain clusters and the geometrical origin of stress in CVD polycrystalline diamond

A mechanism for crystal twinning in the growth of diamond by chemical vapour deposition

“…Hence, one nitrogen atom (in the form of CN) can dramatically increase the rate of carbon atom growth by enhancing the nucleation of next layer growth on {111} surfaces! Other consequences are the increased twinning and defect generation, which are supported by experimental observation (Steeds et al 1998(Steeds et al , 2003Hunt 1999). The lifetime of CN adsorbates on the surface will be limited by thermal desorption and hydrogenation reactions, forming CH x N y (xZ1, 2; yZ1, 2) adsorbates, which are then subject to beta-scission reactions.…”

X-ray photoelectron and Raman studies of microwave Plasma Assisted Chemical Vapour Deposition (PACVD) diamond films

“…Consequently the observed splitting for the Raman diamond line of sample B may be interpreted from a strict mechanical point of view, including the boundary and the stacking faults effects. When the rapid growth by formation of a <110> fibre axis symmetrically generates in-plane internal stresses [50], particularly along the <100> and <111> directions, the difference of stress sign (compressive for  s and tensile for  d ) for <110> oriented diamond crystals is attributed to either the grain boundary structure of <110> oriented films or a non uniform distribution of defects inside the crystals [51]. This behaviour is associated to a highly heterogeneous strain field arising from the most dominant planar structural defects such as twins and stacking faults [44].…”

Optical Study of Defect Distributions in CVD Diamond

“…For instance, inhomogeneous distributions of defects and impurities between different growth sectors are possible, but for high quality diamond films it is unlikely. Transmission electron microscopy of diamond films [16][17][18] also result in conclusion that high anisotropic stress is caused by the deformations of diamond lattice during the grain coalescence and twinning.…”