Polarization Behavior And Energy Storage Property For Silicon-doped Hafnium Oxide Antiferroelectric Thin Films

The development of a wide variety of wearable,portable and even implantable devices raises a higher demand for the size of the energy supply unit.Traditional energy storage solutions,such as supercapacitors,lithium batteries and fuel cells,are not suitable for fast charging and discharging applications for small devices because of their small power density.Although the electrostatic capacitor has very high power density,its small energy storage density cannot meet the energy storage needs of the small-size energy supply unit.At present,the best way to improve the energy storage density of the electrostatic capacitor is to use the antiferroelectric material as the dielectric layer to prepare the electrostatic capacitor because its nonlinear polarization can obtain higher energy storage density under the same applied voltage.However,the compatibility of perovskite antiferroelectrics with current silicon based semiconductor technology is temporarily unable to be put into practical application.In recent years,the doped hafnium oxide antiferroelectric film is expected to be the best choice for the preparation of high energy density electrostatic capacitor because of its high k material application background.In this paper,the 6 mol%Si doped HfO₂ antiferroelectric thin film is used as the research object.Through the electrical measurements,we investigate the dependence of the external electric field,the stability in different temperature and the fatigue properties of the energy storage properties of the fluorite-type antiferroelectric thin films systematically.The experimental results show that owing to high field induced polarization and slim double hysteresis,an extremely large ESD value of 61.2 J/cm³ is achieved at 4.5 MV/cm,which is higher than that of any other reported electrostatic capacitors.In addition,it is found that the decreased temperature leads to the transition of the nonpolar tetragonal phase to the ferroelectric orthorhombic phase,and low temperature is favorable to the stability of the orthorhombic phase.All these phenomena can be explained by the first order phase transition theory.Additionally,the energy storage properties of the films also show excellent temperature stability.In the wide temperature range of 210⁴00 K,the variation ranges of energy storage density of Si doped HfO₂ antiferroelectric thin films is 40.5⁵4.2 J/cm³,which is less than 15%of the corresponding value in room temperature（300 K,47.8 J/cm³ under 3.5 MV/cm electric field）.In the fatigue measurement,the Si doped HfO₂ antiferroelectric film shows excellent fatigue resistance.After 10⁹ cycles,the remnant polarization increases and the maximum polarization is rather stable.we partially adopt the widely recognized switching-induced charge-injection model to interpret our experimental results.Finally,the fatigue effect on the energy storage properties of the Si doped HfO₂ antiferroelectric film is discussed.It is found that the energy storage density of the film is maintained at 43 J/cm³ after bipolar field cycling up to 10⁹ cycles,which is reduced by 18%compared with the initial value.It shows that the energy storage properties of the Si doped HfO₂ antiferroelectric film have excellent endurance characteristic.