Radiation hardness of single crystal CVD diamond detector tested with MeV energy ions

Abstract

The spectroscopic properties of a commercial high purity single crystal diamond detector (1mm2 area, 500μm thickness) have been studied using focused ion beams (H, He and C ions) in the MeV energy range. A measured relative energy resolution of 1.3% (FWHM=25keV) for the detection of 2MeV protons demonstrated a good spectroscopic performance of the CVD diamond device, which makes it useful for the detection of light ions or atoms. To test the radiation hardness of the diamond detector, it was selectively irradiated with a 6.5MeV focused carbon beam up to a fluence of 1011 ions/cm2. Reliable measurement of the ion fluence was accomplished by means of the microprobe single ion technique IBIC (ion beam induced charge). After irradiations that produced selectively damaged regions in the diamond detector, low current mode IBIC microscopy has been performed to measure the degradation of the charge collection efficiency (CCE). In order to get a better understanding of the detector performance after irradiation, different ions with the end of a range smaller, equal and larger than the extend of the damaged layer were used as IBIC probes. The same experimental procedure of irradiation and IBIC microscopy has been performed on a detector grade silicon PIN diode in order to directly compare the radiation hardness of diamond and silicon. The presented results show that the single crystal CVD diamond is less radiation hard for the spectroscopy of short range heavy ions compared to the high resistivity silicon, which is contrary to the results obtained for diamond detectors exposed to the high energy particles.