Radiation detection devices made from CVD diamond

CVD diamond is a remarkable material for the fabrication of radiation detectors. The radiation hardness, chemical resistance and high-temperature operational capabilities of diamond motivate its use in the fabrication of devices operating in hostile environments such as those encountered in the nuclear industry and high-energy physics. Synthetic diamond can be grown using the microwave plasma-enhanced chemical vapour deposition technique. However, the material exhibits several difficulties that require its optimization in terms of the sensitivity or stability of the detector response. Also, defect level influence on the detection characteristics was studied as they are the cause of an observed instability. We report here on the techniques that can be used in the preparation of films that satisfy the requirements for a range of specific detection applications. This can be achieved by fine-tuning the growth conditions and the device preparation steps. Films with thicknesses ranging from 5 to 500 mum have been used for detector fabrication. Here we present the recent developments studied at CEA in Saclay for material optimization of a few applications including radiation hard counters, x-ray intensity, shape and beam position monitors, solar blind photodetectors and high dose rate gamma-meters.