Epitaxial Growth of Diamond Thin Films on Large-scale Smooth Sapphire Substrate

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We propose a new method for the synthesis of diamond films via a hydrogen-free vapor phase route of pulsed laser ablation of a graphite target in a low-pressure pure oxygen atmosphere. The evidence from microscopic, diffraction and spectroscopic techniques indicates that high-quality diamond crystals can be nucleated and grown epitaxially on sapphire (single-crystal aluminum oxide) substrates without diamond-powder treatment at the temperatures lower than 600℃ under the optimized growth conditions of oxygen pressures and pulsed KrF-excimer laser ablation. The spectroscopic property of a laser plasma plume produced during pulsed laser ablation of graphite in an oxygen gas was examined by using the time-resolved optical emission measurements in order to discuss the vapor phase reaction and film growth mechanism.