Thick CVD diamond films grown on high-quality type IIa HPHT diamond substrates from New Diamond Technology

The suitability of type IIa diamonds prepared by High Pressure High Temperature (HPHT) in cubic presses at New Diamond Technology was assessed as substrates for the growth of thick detector-grade quality Chemically Vapour Deposited (CVD) diamond films. The substrates were found to possess a moderate dislocation density of about 10(3) cm(-2) and a reduced amount of residual impurities as compared to standard type lb crystals. Using these diamonds as seeds for homoepitaxial growth, CVD films with improved structural characteristics were obtained although extended defects could not be completely prevented from forming and propagating. Their performance as detectors for beta radiation was however improved leading to almost full charge collection which shows significant improvement as compared to CVD films grown under the same conditions on standard lb HPHT diamonds. The availability of this new material source opens the way to the fabrication of higher quality CVD material for electronics applications.