The effect of substrate position on the orientation and interfacial reaction of epitaxial diamond on silicon

Diamond was grown on silicon substrates by microwave plasma-enhanced chemical vapour deposition with pretreatment consisting of carburization and biasing. Cross-sectional transmission electron microscopy shows that epitaxial diamond can be directly grown on Si(110). The orientation of epitaxial diamond varies with the substrate position under the plasma ball. At the central part of the substrate, diamond is mainly in a cube-on-cube orientation relationship with silicon which is 〈110〉dia//〈110〉Si and {111}dia//{111}Si. Away from the centre, five different orientation relationships are observed. The defect density of the diamond film is also dependent on the substrate position. For Si(100) substrates, the interfacial structure between diamond and Si also varies as a function of the substrate position. An SiC interlayer is formed after the bias and growth stages of deposition. The amorphous carbon, deposited in the carburization step, may react with Si to form SiC. Plasma inhomogeneity plays an important role in the variation of the diamond orientation. In addition, the composition and structure of the interlayer formed between diamond and silicon depend on the position under the plasma.