Fabrication and characterizations of large homoepitaxial single crystal diamond grown by DC arc plasma jet CVD

Abstract

Homoepitaxial diamond layers have been grown on HPHT synthetic type Ib (100) single crystal diamond plates brazed on a Φ65mm Mo holder using a commercial type 30kW dc arc plasma jet CVD with rotating arc root and operating at gas recycling mode with gas mixture of Ar/H2/CH4. The effects of substrate temperature and CH4/H2 ratio on the surface morphology, the growth rate and the quality of the synthesized diamond have been studied using optical microscopy and Raman spectroscopy. The growth rate up to 17.4μm/h has been obtained in the single crystal diamond sample deposited at 1000°C with CH4/H2=0.813%, exhibiting relatively smooth surface morphology with the typical feature of step-flow growth, without any non-epitaxial diamond crystallites. Under the optimum synthesis conditions, large size (7.5mm×7.5mm) polished freestanding single crystal diamond plate up to 1.03mm thickness has been produced and characterized by UV–vis–IR absorption, photoluminescence and Raman spectroscopy, as well as high-resolution X-ray diffraction. It was demonstrated that the quality of the as-grown CVD single crystal diamond was close to that of the natural type IIa single crystal diamond. It was shown that the epitaxial growth of high quality CVD single crystal diamonds could be achieved over the entire Φ65mm Mo holder on which a large quantity of CVD single crystal diamonds could be grown simultaneously. This is of economical importance in the development of high power DC arc plasma jet CVD systems for fabricating large size, high quality CVD single crystal diamond.