CVD diamond particle detectors

Abstract

Abstract CVD diamond's advantage as a particle detector over other materials is its radiation-hardness, its low atomic number, its high atom density and its robustness in hostile environments. It is possible to impose a very high electric field across a diamond, under which the electrons and holes created by an incident particle separate and are collected by electrodes on the surface of the film. The radiation-hardness is one of the supreme advantages of diamond over more conventional detector materials. We have investigated the radiation effects of high doses of neutrons, electrons, protons and alpha particles in diamond and compared the results to those in silicon, which is used for most conventional detectors of this type. The computer simulation packages GEANT and TRIM were used to plot the interactions of the incident particles with the diamond and the damage that they and the displaced carbon atoms cause within the solid. However, most of this damage anneals away while the irradiation continues, so we take into account the processes whereby interstitials recombine with vacancies. We can then show the damage profiles caused by these particles incident at energies of 1 MeV or other energies. The results confirm that approximately twice the number of vacancies are created in silicon compared to diamond. At room temperature, vacancies in silicon migrate to form complex defects with dopants, whereas in diamond, the vacancies are immobile, and the detectors are not doped. Therefore, the effect of the radiation damage in diamond on the operation of the detector is much less severe than equivalent damage would be on a silicon device.