Co-60 gamma radiation influences on the electrochemical, physical and electrical characteristics rare-earth dysprosium oxide (Dy2O3)

摘要

Dysprosium Oxide (Dy2O3) gate dielectric layers were deposited by Electron-Beam evaporation onto p-Si (100) wafers. The effects of gamma irradiation on the physical, electrochemical, and electrical properties of Dy2O3/p-Si thin films were investigated in detail. 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/omega-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 local heating aggregated the smaller grains into a bigger cluster. In addition, the surface roughness was increased after irradiation indicating that deforms the films' surface morphology. The XPS analysis revealed that electrochemically two different phases exist in 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 increasing dose, which are correlated with the generated interface state density and/or improvement of dielectric characteristics of Dy2O3 owing to oxygen diffusion.