RAPID GROWTH OF SINGLE-CRYSTAL DIAMOND ON DIAMOND SUBSTRATES

Recently an account of the homoepitaxial growth of diamond in an oxygen-acetylene combustion flame was published (J. Cryst. Growth, 104 (1990) 752). Notwithstanding the high deposition rate (50-mu-m-1 h), the material had good optical quality. After removal of the natural diamond substrate from one of the samples, it was proved that the deposit was single-crystal diamond. However, most of the optical properties were measured with the layers still attached to the substrate. In this study more elaborate characterizations of the free-standing, flame-grown diamond are described. Hydrogen, nitrogen and perhaps oxygen are identified as impurities, based on IR spectroscopy and both photoluminescence and cathodoluminescence (PL and CL). The distribution of the impurities is non-uniform, as was verified by CL topography and stress birefringence microscopy. Following the standard classification rules the flame-grown diamond is neither type I nor type II.