Spectroscopic Studies of High Performance CdTe-Based Schottky Diode X/γ-Ray Sensors

The Ni/CdTe/Au Schottky diode X/γ-ray sensors, fabricated using the Ar-ion bombarding technique, exhibit low leakage current density (~20 nA/cm2 at 1000 V) and high energy resolution (~1.0%@662 keV). We present and analyze the dependencies of the 137Cs isotope energy spectra on the applied bias, the distance between the sensor and the radiation source, and the operation time. Despite the small (1 mm) CdTe crystal thickness, resulting in low radiation absorption and, therefore, a low probability of γ-photon capture and thus generation of electron-hole pairs, the sensors demonstrated high detection efficiency. This can be attributed to a high potential barrier at the Ni/CdTe Schottky contact, allowing the application of high bias voltages and ensuring a complete charge carrier collection.