Structure and morphology of oriented diamond films.

Fibre textured as well as heteroepitaxially textured diamond films have been grown by microwave plasma assisted CVD on silicon substrates. The texture axis is determined by the growth parameter alpha = square root3 V sub 100/V sub 111, which in turn depends on the growth temperature and the gas composition. The overgrowth of heteroepitaxially oriented nuclei also depends on alpha. Growth under alpha about 3 improves the orientation of heteroepitaxially textured films on (100) substrates, whereas much smaller a leads to a complete loss of the epitaxial orientation. It is shown that twinning causes this instability. The twin formation for various alpha values has been modelled giving full explanation of the observed growth morphologies.