Recent improvements in detection performances of radiation detectors based on bulk semi-insulating InP

In this work, bulk semi-insulating (SI) InP wafers of four various producers have been used for the fabrication of radiation detectors. The tested detectors were prepared starting from the different materials in just one run in order to be sure that their performances were not influenced by technological processes. On one type of material various electrode technologies were used with the aim to analyze their role on the detector performances. The fabricated detectors were tested for detection performance by the 241Am and 57Co gamma-ray sources at below room temperature. The best detector was calibrated and tested also using 133Ba and 137Cs gamma sources. The best detector gives an energy resolution of 7 keV FWHM and a charge collection efficiency (CCE) of 82% (59.5 keV photopeak) at a temperature of 216 K. According to our knowledge, these results are the best which have been obtained with InP radiation detectors till now. The operation of SI InP detector at room temperature is demonstrated and discussed. In general, the CCE and the energy resolution of radiation detectors fabricated on bulk SI InP materials showed a strong dependence on the electrode technology as well as the base substrate quality