Systematic study of the response of single crystal diamond neutron detectors at high temperature

For many years artificial diamond detectors have been studied for application in high temperature environments. An open question is whether the performance of such detectors is influenced by the electrical contacts. In the attempt to better understand this point, a systematic study of electrical contacts deposited with different techniques and materials on top of commercial artificial single crystal diamond (SCD) films was performed. In this paper we report on the results obtained using three types of electric contacts produced both using metal and not metal layers: a) double Schottky, b) double ohmic, c) Schottky-ohmic contacts. The detectors were studied under 14 MeV neutron irradiation, and were operated in pulse mode. The pulse height spectra (PHS) produced by the 14 MeV neutrons were recorded as a function of temperature and the detector behaviour was studied by analysing the variation of the peak produced in the PHS by the C-12 (n, alpha)Be-9 reaction induced by 14 MeV neutrons in carbon.The maximum operational temperature limit of the tested detectors was found to be around 230 degrees C and it resulted to be slightly dependent, within +/- 10 degrees C, upon the type of the electrical contact. It turned out that, together with the type of the electrical contact, other parameters such as the intrinsic diamond properties and the film thickness have to be considered to understand the response of the detector at high temperature.