Depolarization Characteristics in Sol-Gel Ferroelectric Pb(Zr 0.4 Ti 0.6 )O 3 Thin-Film Capacitors

Properties of SrBi 2 Ta 2 O 9 ferroelectric thin films prepared by a modified metalorganic solution deposition technique Appl.Ferroelectric capacitors having sputtered Pt bottom and top electrodes and metalorganic decomposition derived ferroelectric thin films of SrBi 2 Ta 2 O 9 ͑SBT͒ were prepared. The thickness effects on the structure, surface morphology, and electrical properties of SBT thin films were studied and discussed. Structure and surface morphology were analyzed by x-ray diffraction and atomic force microscope. The electrical properties were characterized by the measurements of hysteresis, capacitance, and pulse switching. The crystalline structure, grain size, and electrical properties do not depend on film thickness when films are less than 440 nm thick. A larger grain size is observed for films thicker than 440 nm, which results in a larger remnant polarization. The thickness dependence of the coercive voltage and reciprocal capacitance can be explained by an interfacial layer model. The thickness-independent coercive field and dielectric constant, calculated from the interfacial layer model, are around 19 kV/cm and 343, respectively. Nonvolatile polarization ( P nv ), obtained from pulse-switching measurements, increases with the applied electric field and finally saturates with a slight thickness effect. The relaxation of the remnant polarization that occurs at zero-voltage intervals between the pulses and the thickness-independent behavior of P nv are explained based on depolarization fields within the ferroelectric due to nonswitching interfacial layers at the film/electrode interfaces.

Section: Pulse-switching Measurementsmentioning

confidence: 99%

Section: Pulse-switching Measurementsmentioning

confidence: 99%

Characterization of metalorganic decomposition-derived SrBi2Ta2O9 thin films with different thicknesses

Ling

et al. 2000

“…12 The metalferroelectric-metal structure does not produce a depolarization field, however, the MF͑M͒IS structure inevitably generates a depolarization field. 13,14 The depolarization field induces leakage current and decreases remanent polarization gradually, 15,16 resulting in poor retention properties of MF͑M͒IS FETs. To decrease the writing voltage and depolarization field effectively, an improved MFMIS structure has been devised, in which the area of the insulating layer is much larger than the ferroelectric layer, i.e., the capacitance of the dielectric layer is 10 times larger than that of the ferroelectric layer.…”

Section: Memory Properties Of a Ferroelectric Gate Field-effect Transmentioning

confidence: 99%

Memory properties of a ferroelectric gate field-effect transistor with an adjoining metal–ferroelectric–metal assistance cell

Xiong

Sakai

Ishii

et al. 2003

Articles you may be interested inA 60nm channel length ferroelectric-gate field-effect transistor capable of fast switching and multilevel programming Appl. Phys. Lett. 99, 182902 (2011); 10.1063/1.3657413 Ferroelectric field effect transistors using very thin ferroelectric polyvinylidene fluoride copolymer films as gate dielectrics A nonvolatile memory element based on an organic field-effect transistorWe prepared a ferroelectric gate field-effect transistor ͑FET͒ memory that consists of a normal metal-ferroelectric-metal-insulator-Si FET and an adjoining metal-ferroelectric-metal auxiliary cell. Due to this cell, the FET exhibited excellent nonvolatile memory properties of low-voltage operation and a long period of retention. After writing-voltage application of Ϯ4 V, the drain current ratio between ''ON'' and ''OFF'' states was as large as six orders of magnitude and the memory window ͑difference in threshold voltage͒ was 3 V. Even 10 4 s after writing, the ON state drain current could be distinguished as being three orders different from the OFF state current. The ferroelectric FET with the auxiliary cell that demonstrated good nonvolatile properties has potential for application in high-density nonvolatile memories.

“…This is sometimes referred to as retention loss, and is widely studied in thin films. [13][14][15][16] Some of the recent studies on polarization relaxation focused on the physical origins of the relaxation kinetics during polarization reversal. Different retention studies covered different time frames, from very short times (tϽ1 s) to long times (tϾ1 s).…”

Section: Introductionmentioning

confidence: 99%

Polarization relaxation anisotropy in Pb(Zn1/3Nb2/3)O3-PbTiO3 single-crystal ferroelectrics as a function of fatigue history

Ozgul

Furman

Trolier-McKinstry

et al. 2004

Polarization relaxation was studied in Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) single crystals that show fatigue anisotropy. To excite prepoled crystals, a modest dc voltage (<1/2 of the coercive field) was applied along the poling direction. Upon removal of the voltage, the polarization decay in the time domain was measured. Experimental data were modeled with a stretched exponential function. Stretching exponent (β〈hkl〉) and characteristic time (τ〈hkl〉) constants for polarization relaxation were determined from data over four decades in the time domain at different stages of bipolar cycling. β〈hkl〉 values after 101 cycles were 0.146±0.002 and 0.247±0.0004 in the 〈001〉 and 〈111〉 orientations, respectively. The β〈111〉 constant increased up to 0.453±0.104 after 105 cycles in 〈111〉 oriented crystals that show fatigue. However, much less change is observed in β〈001〉 as a function of cycling for 〈001〉 crystals. Characteristic time constants for relaxation (τ〈hkl〉) were calculated for 〈001〉 and 〈111〉 orientations as 0.401±0.048 s and 57.46±0.10 s, respectively. These results suggest a faster polarization relaxation in 〈001〉 than in the 〈111〉 orientation of rhombohedral PZN-PT ferroelectric crystals.