Internal stresses and microstructures of commercial thick diamond films deposited by different deposition methods

Structures and stress state of six commercial freestanding thick diamond fi lms (> 300 mum) were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and Raman spectroscopy. T hese films represent the typical samples synthesized by three different che mical vapor deposition (CVD) methods, including DC are, microwave plasma, a nd hot filament. It was found that the higher diamond deposition rate it re aches, the more non-diamond carbons it contains, and the larger the residua l compressive stress it possesses. Moreover, the samples with the highest d egree of optical transparency are under the lowest compressive stress. Thes e crystal characteristics can be manipulated by selecting different deposit ion methods and parameters that affect nucleation rate and growth rate of d iamond. The present results show that the DC are method gives poorly develo ped crystals, and its residual compressive stress of the films is the highe st due to the fastest diamond nucleation and crystal growth rates. (C) 2001 Elsevier Science B.V. All rights reserved.