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Ionic Gating of Ultrathin and Leaky Ferroelectrics
摘要： Ionic liquids are used to induce reversible large area polarization switching in ultrathin and highly defective ferroelectric films. Long range electrostatic charge control is induced by modifying the electric double layer at an ionic liquid–PbZr0.2Ti0.8O3 interface with electrostatic and electrochemical control of polarization orientation in the ferroelectric layer. The localized nature of the ionic gating mechanism prohibits the presence of leakage current, which has historically limited the switching of ultrathin and/or electrically leaky ferroelectric films in solid metal-gated capacitor devices. This is demonstrated on ultrathin films and in massively defective films with >30% coverage of direct conducting channels running from surface to ground. This approach opens new design possibilities for integrating ultrathin ferroelectric films in functional electronic devices.
关键词： ferroelectrics,polarization switching,ionic liquids,ionic gating,device structure
更新于2025-09-23 15:22:29
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Polarization and charge carrier density coupling in epitaxial PbZr <sub/>0.2</sub> Ti <sub/>0.8</sub> O <sub/>3</sub> /ZnO heterostructures
摘要： The integration of ferroelectric materials with semiconductor heterostructures can greatly enhance the functionality of electronic devices, provided the ferroelectric material retains a significant part of its switchable polarization. This work reports polarization switching in epitaxial PbZr0.2Ti0.8O3/ZnO/GaN heterostructures grown on c-cut sapphire single-crystal substrates. The electrical measurements of PbZr0.2Ti0.8O3/ZnO ferroelectric/semiconductor capacitors reveal an unexpected difference between a counterclockwise ferroelectric hysteresis loop and a clockwise C-V loop. A non-linear hysteretic behavior of the capacitance is observed in the voltage range that is at least 3 times narrower than the range of ferroelectric polarization switching voltages. This difference can be explained by charge injection effects at the interface between ferroelectrics and semiconductors. The interaction between electric polarization and the electronic structure of the heterojunction leads to capacitance and charge carrier concentrations that are switchable by polarization of the ferroelectric layer. These findings are important for both fundamental and applied research of switchable and highly tunable ferroelectric/semiconductor heterostructures.
关键词： ferroelectric materials,polarization switching,charge injection effects,capacitance,semiconductor heterostructures
更新于2025-09-23 15:21:01
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Dielectric properties of self-assembled spherulite films of organic ferroelectric 2-methylbenzimidazole
摘要： Thin films of organic ferroelectric 2-methylbenzimidazole (MBI) were grown by evaporation method on different substrates. The films consist of self-assembled spherulite blocks formed by elongated crystallites of MBI. Temperature, frequency, and electric field amplitude variations of in-plane hysteresis dielectric loops were measured using interdigital system of electrodes and compared with analogous dependences in MBI single crystals. Simulation of remnant polarization Prem dependence on amplitude of electric field Emax in films is carried out in frames of a model considering the dipole moment of block as a sum of dipole moments of crystallites, which form spherulite with account of different orientation of crystallites relative to applied electric field. Deviations from the model are assosiated with complicated domain structure and presence of depolarizing fields.
关键词： Split crystals,organic ferroelectrics,polarization switching
更新于2025-09-12 10:27:22
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Frequency-induced polarization switching and bistability in a 1550?nm VCSEL subject to parallel optical injection
摘要： We experimentally investigate frequency-induced polarization switching (PS) and bistability (PB) characteristics in a 1550 nm vertical-cavity surface-emitting laser (1550 nm VCSEL) subject to parallel optical injection, for which the polarization direction of the injection light is along with the direction of dominant polarization mode in the solitary 1550 nm VCSEL. The results show that, for a 1550 nm VCSEL under parallel optical injection with frequency detuning ?ν (= νinj ? ν0, where νinj is the frequency of injection light and ν0 is the frequency of dominant polarization mode of the solitary 1550 nm VCSEL), type I PS (the dominant polarization mode switches from Y-polarization mode with a shorter wavelength to X-polarization mode with a longer wavelength) and type II PS (the dominant polarization mode switches from X-polarization mode to Y-polarization mode) can be observed through continuously scanning the frequency of injection light. Moreover, the values of ?ν required for generating PSs are dependent on the variation route, namely frequency-induced PB phenomenon occurs. In the region with negative ?ν, there exist two hysteresis loops, whose widths are seriously influenced by the injection power and the biased current.
关键词： 1550 nm vertical-cavity surface-emitting laser (1550 nm VCSEL),Polarization bistability (PB),Parallel optical injection,Polarization switching (PS)
更新于2025-09-09 09:28:46