Device performance of chemical vapor deposition monocrystal diamond radiation detectors correlated with the bulk diamond properties

Diamond radiation detectors (DRDs) based on type-IIa chemical vapor deposition (CVD) monocrystal diamond are more suitable for engineering applications with high consistency requirements due to the lower cost and property controllability. However, their saturated charge collection efficiencies (CCEs) have huge differences. Six type-IIa CVD monocrystal diamond plates were analyzed by the Fourier transform infrared spectrometer, high resolution x-ray diffraction, Raman spectroscopy, photoluminescence and secondary ion mass spectroscopy. Then DRDs were fabricated by them and the CCEs were measured under the irradiation of Am-241 source. The results show that the most important factor restricting CCEs are the impurities in the diamond plates, while dislocations with a density <1 x 10(7) cm(-2) for all samples have weaker impact in our case. The reason is that the carrier mobility-lifetime (mu tau) product of diamond is more strongly influenced by impurities in this dislocation density range. Thinning diamond plate, if the thickness is kept above 100 mu m, is not a good means to obtain high performance DRDs. Therefore, to further improve the detector performance, ultra-high purity diamond growth is most important. Moreover, a diamond test and selection scheme for high performance DRDs is also demonstrated.

Automated summary

The study found that impurities in diamond plates have the most significant impact on the performance of diamond radiation detectors, while dislocations have a weaker effect on CCEs. Moreover, maintaining a thickness of diamond plates above 100μm is crucial for obtaining high-performance detectors.