Abstract
Hafnia-based ferroelectric materials,like Hf0.5Zr0.5O2(HZO),have received tremendous attention owing to their potentials for building ultra-thin ferroelectric devices.The orthorhombic(O)-phase of HZO is ferroelectric but metastable in its bulk form under ambient conditions,which poses a considerable challenge to maintaining the operation performance of HZO-based ferroelectric devices.Here,we theoretically addressed this issue that provides parameter spaces for stabilizing the O-phase of HZO thin-films under various conditions.Three mechanisms were found to be capable of lowering the relative energy of the O-phase,namely,more significant surface-bulk portion of(111)surfaces,compressive c-axis strain,and positive electric fields.Considering these mechanisms,we plotted two ternary phase diagrams for HZO thin-films where the strain was applied along the in-plane uniaxial and biaxial,respectively.These diagrams indicate the O-phase could be stabilized by solely shrinking the film-thickness below 12.26 nm,ascribed to its lower surface energies.All these results shed considerable light on designing more robust and higher-performance ferroelectric devices.
基金项目
Fund from the Ministry of Science and Technology(MOST)of China(2018YFE0202700)
National Natural Science Foundation of China(11974422)
National Natural Science Foundation of China(12104504)
Strategic Priority Research Program of the Chinese Academy of Sciences(XDB30000000)
Fundamental Research Funds for the Central Universities()
Research Funds of Renmin University of China(22XNKJ30)
NETL
NSTL
万方数据