Study on low temperature growth and formation mechanism of hexagonal diamond

Synthesis of hexagonal diamond on Al/Ni coated thermally oxidized SiO₂ covered Si wafer substrate with photo-enhanced chemical vapor deposition (CVD) method at 450 °C is reported here. The Raman spectroscopy on grown samples shows a 1322 cm^{- 1} peak with 75.4 cm^{- 1} full width at half maximum (FWHM). The X-ray diffraction (XRD) data shows hexagonal diamond peaks. Various stages of hexagonal diamond formation are observed in the scanning electron microscope (SEM) images. Based on these images, a mechanism of hexagonal diamond nucleation and growth is proposed.