AP Seminar - Properties of Oxygen Vacancies and Correlated Physical Effects in HfO2-based Thin Films

Various magical and wonderful physical effects and properties have been demonstrated in the HfO₂-based thin films and devices such as high K gate dielectrics in CMOS, resistive switching in resistance random access memory (RRAM), the robust ferroelectricity in ferroelectric devices, and so on. Those excellent characteristics have triggered the extensive research interests of both the fundamentals and applications for the HfO₂-based thin films.  However, the underlying physical mechanisms that dominate those demonstrated characteristics in the HfO₂-based thin films and devices are still argued. Various theoretical and experimental results showed that the observed fantastic properties in HfO₂-based thin films and devices are strongly correlated with the behaviours of oxygen vacancy defects existed in HfO₂-based thin films. In this talk, we will try to understand the fantastic characteristics observed in HfO₂-based thin films from the unified viewpoint, which is related to the essential microscopic natures of oxygen vacancy defects such as the features of the vacancy defect states and distributions, and the evolution behaviours. From the unified viewpoint, the various observed characteristics such as the Fermi-level pinning effect in high-K/metal gate stacks, the resistive switching behaviours can be well quantified. Moreover, we may expect that much more newly physical properties are measured in HfO₂-based devices.