Improving Energy\nResolution of CdSe-Based γ‑Ray\nDetectors\nthrough Asymmetric Schottky Contact Engineering Using Oxygen Plasma\nTreatment

When creating a Schottky contact to suppress the leakage\ncurrent\nof semiconductor γ-ray detectors and improve their energy resolution,\nit is successfully employed the fact that the formation of a Schottky\nbarrier is determined not only by the difference in the electrode\nand semiconductor work functions but also affected by the semiconductor\nsurface state. Oxygen plasma (OP) treatment has been used to modify\nthe surface states of CdSe single crystals (SCs) prior to the Au electrode\ndeposition, thereby creating a Schottky contact at the metal–semiconductor\ninterface. The <i>n</i>-type Schottky contact formation\nhas been confirmed by the <i>I</i>–<i>V</i> characteristics and ultraviolet photoelectron spectroscopy analysis.\nX-ray photoelectron spectroscopy has shown that the stoichiometric\nstate of the CdSe SC surface changes from a Cd-deficient (untreated\nsurface) to a near-ideal stoichiometric (OP-treated surface). In addition,\na newly formed CdSeO<sub>3</sub> component has been revealed, which\nis beneficial for suppressing the surface leakage current. The Au/CdSe/Au\nradiation detector with the single-sided OP-treated surface (Schottky\ndiode) exhibits a higher energy resolution of (23.93 ± 0.89)%\nfor <sup>241</sup>Am 59.5 keV γ-rays compared to that of the\ndetectors without surface treatment ((44.66 ± 2.25)%). The energy\nresolution of the champion CdSe-based Schottky diode type γ-ray\ndetector for <sup>241</sup>Am 59.5 keV γ-rays can reach 22.72%.