Growth of high-quality homoepitaxial diamond films by HF-CVD

Abstract Defined growth of high-quality crystalline diamond films is necessary for manufacturing of electronic devices. Several groups have already worked on this topic and the main challenges remaining are the suppression of crystalline defects, the reduction of impurities and higher growth rates. High-quality homoepitaxial diamond films were produced in a hot filament chemical vapor deposition (HF-CVD) system with and without addition of nitrogen to the gas phase. Substrates were (100)-oriented synthetic Ib diamonds (Sumitomo) with a maximum misorientation angle of 0.3° as determined by X-ray diffraction. By adjusting the α-parameter independently to a value close to two using polycrystalline diamond films on silicon growth rates of up to 500 nm/h could be achieved while simultaneously keeping the density of unepitaxial crystallites below 10 cm −2 . The surface roughness (RMS) was below l nm in a 1×1-μm 2 area. Impurities were studied by photoluminescence and cathodoluminescence spectroscopy. For the films deposited without intentional nitrogen addition, nitrogen-related impurities could only be detected by low temperature photoluminescence indicating a very low concentration. At 1.68 eV we observed the signature of the Si-vacancy complex probably caused by evaporation of Si from the tungsten filament.