title: Tunable tunneling electroresistance in ferroelectric tunnel junctions by mechanical loads.
abstract: Combining nonequilibrium Green function's approach with density functional theory, effects of the applied mechanical loads on polarization, electrostatic potential, and tunneling conductance of a ferroelectric tunneling junction (FTJ) have been investigated. Using the first principle calculations, we show that compressive strains can induce and enhance the polarization in ferroelectric tunnel barriers, and practically achieve ferroelectricity in two unit cell thickness under a -2.2% compressive strain. More importantly, mechanical strains can significantly change the effective electrostatic potential in FTJ and thus control its tunneling conductance, which is defined as giant piezoelectric resistance (GPR) effect. Our calculations indicate that GPR effect is particularly significant near the paraelectric/ferroelectric phase transition, and increases exponentially with the barrier thickness. Furthermore, it is also found that defects of oxygen vacancies and nitrogen doping have little impact on GPR ratio of strained FTJ. Because of its high-sensitivity to external mechanical loads, FTJ with GPR effect should be adequate for applications in agile mechanical sensors, transducers, and other multifunctional devices.
authors.affiliation: State Key Laboratory of Optoelectronic Materials and Technologies/Institute of Optoelectronic and Functional Composite Materials, Micro-Nano Physics and Mechanics Research Laboratory, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Luo
authors.forename: Biao
authors.initials: B
authors.lastname: Wang
authors.forename: Yue
authors.initials: Y
authors.lastname: Zheng
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004579:Electron Transport; D004867:Equipment Design; D019544:Equipment Failure Analysis; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D008962:Models, Theoretical; D012666:Semiconductors; D013314:Stress, Mechanical