RAP Conference Proceedings, vol. 4, pp. 156–161, 2019 ISSN 2466-4626 (online) | doi: 10.37392/RapProc.2019.32 WWW.RAP-PROCEEDINGS.ORG Co-60 GAMMA RADIATION INFLUENCES ON THE ELECTROCHEMICAL, PHYSICAL AND ELECTRICAL CHARACTERISTICS OF RARE-EARTH DYSPROSIUM OXIDE (Dy 2 O 3 ) Umutcan Gürer 1,2 , Ercan Yilmaz 1,2* 1 Nuclear Radiation Detectors Research and Applications Center, BAIBU, Bolu, Turkey 2 Physics Department, Bolu Abant Izzet Baysal University, Bolu, Turkey Abstract. In this study, the effects of gamma irradiation on the physical, electrochemical, and electrical properties of Dy2O3/p-Si thin films have been studied. For this, the rare earth oxide (Dy2O3) was deposited onto p-Si wafer by using an e-beam evaporation technique. The evolutions on the crystallographic and morphologic characteristics of the films under gamma irradiation were analyzed by X-ray diffraction (XRD) and Atomic Force Microscopy (AFM), respectively, while irradiation effects on the electrochemistry of the films were characterized by X-ray photoelectron spectroscopy (XPS). Furthermore, variations on the electrical characteristics of Dy2O3/p-Si thin films were also specified by Capacitance-Voltage (C-V) and Conductance-Voltage (G/ω-V) measurements. No significant changes on the crystallographic orientation were observed after gamma irradiation exposures. However, the grain size of the films was increased slightly due to the fact that the local heating aggregated the smaller grains into a bigger cluster. In addition, the surface roughness was increased after irradiation indicating that it deforms the films’ surface morphology. Two different intense intermixing phases revealed the presence of the electrochemical analysis of the virgin Dy2O3/p-Si thin films. These phases are Dysprosium sub-Oxide (DyxOy) and Oxygen deficient in Dy2O3 films. After irradiation exposures, Oxygen incorporation, vacancy, and interstitial defects formation were observed in the electrochemical characteristics of the films. On the other hand, the capacitance curves exhibit kinks in the region between depletion and accumulation due to the presence of the intermixing phases of Dy2O3 films. The capacitance of samples significantly increased with the increase of radiation doses, which are correlated with the generated interface state density and/or improvement of dielectric characteristics of Dy2O3 owing to Oxygen diffusion. Keywords: MOS Capacitor, high-k dielectric, rare earth oxide, Dy2O3, irradiation * yilmaz@ibu.edu.tr 1. INTRODUCTION Metal-oxide-semiconductor (MOS) devices have become a crucial base of modern microelectronics technology since their discovery. Continuous developments of the MOS based technology are still focusing on the improvement of device performance. In this aspect, researchers exhibit great efforts to replace the conventional insulating SiO2 layer with suitable high-k dielectric materials in the MOS transistor applications. High leakage current and unfavorable SiOx and/or silicate phases are the major issues for the usage of the high-k dielectric materials in gate dielectric applications [1]–[4]. Therefore, Rare Earth Oxides (REOs) gained a lot of attention for the improvement of the MOS devices [5]–[8]. Various REOs such as Yb2O3 [9], Gd2O3 [10], [11], Sm2O3 [12], Y2O3 [13] have been reported. As a possible replacement for gate dielectrics, Dy2O3 is one of the most promising REO materials owing to its high dielectric constant (k = 14-18), a large energy band gap (4.9 eV), and thermal and chemical stability with silicon [14]–[16]. Researchers have already reported that Dy2O3 exhibits promising performance in gate dielectric applications [5], [17], [18]. However, together with these initial studies, the stability of the device should be investigated in various environments including the irradiation field to test the device reliability. To the best of our knowledge, the device characteristics under the irradiation exposure have not been investigated in great detail for the devices having the Dy2O3 gate dielectric. In this study, Dy2O3 was deposited on the p-Si substrate by the electron beam deposition (e-beam) technique to investigate the effect of Co-60 gamma radiation on the Dy2O3 device. The devices were exposed to Co-60 gamma irradiation up to 4000 Gy. The structural and morphological evolutions after gamma irradiation exposures were determined with X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM), respectively. The variations in the electrochemical structure of the Dy2O3/Si stack were investigated by X-ray photoelectron spectroscopy (XPS). The electrical characteristics of the device, capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements were carried out. 2. EXPERIMENTAL DETAILS The Dy2O3 thin films were fabricated on a p-type silicon (100) following a standard RCA (Radio Corporation of America) cleaning process. The