Characterization of CdTe/n$^{+}$-Si Heterojunction Diodes for Nuclear Radiation Detectors

CdTe/n+-Si heterojunction diodes were fabricated and characterized for the development of gamma ray detectors. With the careful control of the growth parameters thick single crystal CdTe epilayers of high-crystalline quality were grown directly on the (211) Si substrates in a metalorganic vapor phase epitaxy. The heterojunction diode was fabricated by growing a 5 mum thick n-type CdTe buffer layer on the n+-Si substrate, followed by the 100 mum thick undoped p-CdTe layer growth. The diode fabricated showed very good rectification property with a low value of the reverse bias leakage current, typically 1.2 times 10-7 A/cm2 for an applied reverse bias of 50V. The diode clearly demonstrated its gamma radiation detection capability by resolving energy peaks from the 241Am radioisotope during the radiation detection test performed at room temperature.