The high energy resolution of Pt/Si alpha particle detector with Al2O3 passivation layer

Schottky type detectors (STDs) are normally used to detect high-energy particles due to their excellent properties, such as simple fabrication technique, linearity, and fast-rising time. Conventional STDs cannot obtain high energy resolution due to the large leakage current working at the reverse bias condition, which is ascribed to the high interface states between metal and substrate. In this study, a thin layer of Al2O3 (<6 nm) is innovatively inserted between metal Pt and silicon substrate to fabricate the Al2O3 passivated Schottky type detectors. In comparison to Pt/Si, it was found that the interface states of Pt/Al2O3/Si could be remarkably suppressed from 1014 eV−1 cm−2 to 1012 eV−1 cm−2. Thus, the lower leakage current of 5 nA was obtained with the reverse bias of 100 V, as compared to the 70 nA without the Al2O3 passivation layer, which greatly reduced the detection noise. The α particles of 239Pu, 241Am, and 244Cm are successfully detected with an energy resolution of 0.56% due to the suppression of interface states.