Huiping Feng

Relationship between texture and residual macro-strain in CVD diamond films based on phenomenological analysis

Abstract The relationship between texture and elastic properties of chemical vapor deposition (CVD) diamond films was analyzed based on the phenomenological theory, which reveals the influence of crystalline orientation and texture on the residual macro-strain and macro-stress. The phenomenological calculations indicated that the difference in Youngs modulus could be 15% in single diamond crystals and 5% in diamond films with homogeneously distributed strong fiber texture. The experimentally measured residual strains of free-standing CVD diamond films were in good agreement with the correspondingly calculated Youngs modulus in connection with the multi-fiber textures in the films, though the difference in Youngs modulus induced by texture was only around 1%. It is believed that texture should be one of the important factors influencing the residual stress and strain of CVD diamond films.

Microstructure and Texture in Free-Standing CVD Diamond Films

Free-standing CVD diamond films were prepared under the substrate temperature in the range of 850-1050oC. Macro- and micro-textures of the films were investigated based on the SEM observation as well as on the ODF and EBSD analysis. It was found that certain growth selection process appeared during diamond deposition which, however, did not lead to a strong film texture. It is indicated that strong fluctuation of growth ratio V<100>/V<111> and frequent growth twinning during film deposition resulted in randomization effect of grain orientations, which can be transformed by adjusting the parameters of film preparation.