Ferroelectric Material Parameters Research Articles

Effect of Temperature on Dielectric Parameters of Ferroelectric Materials at Microwave Frequency

The composite materials of ST & BT ceramics were prepared by using solid state reaction method. The dielectric parameters of ST & BT ceramics of particle size 125 micron like dielectric constant (ε'), loss (ε"), quality factor (QxF), relaxation time (τ) and conductivity (σ) has been studied at different temperatures i.e. -10°C, +10°C, +30°C and +50°C. the values of dielectric parameters are found greeter of ST then BT but the relaxation time of ST is found smaller than BT.

Effect of Negative Capacitance in Partially Ground Plane based SELBOX FET on Capacitance Matching and SCEs

Here in, we investigated the impact of negative capacitance in PGP-SELBOX NCFET (partial ground plane on a selective buried oxide in negative capacitance FET) over FDSOI. The ferro-electric layer is placed in the gate stack of PGP-SELBOX NCFET to generate the negative capacitance phenomenon. Ferro-electric(FE) materials are similar to dielectric materials but differ in terms of their polarization properties. FE-HFO2 is used as ferroelectric material due to its sufficient polarization rate with high dielectric capacitance and better reliability. The effect of ferro-electric material parameters like coercive field(Ec) and remnant polarization(PR) on the capacitance matching of NCFET are analyzed. The simulation results reveal that the RPE factor, which is the ratio of PR to Ec, is closely related to better capacitance matching. In addition, the effect of variation in thickness of ferro-electric layer on the average sub-threshold swing(SS) is also explored. The relation between short channel effects (Vth rolloff and DIBL) and thickness of the ferro-electric (tfe) for PGP-SELBOX NCFET is also analyzed. The simulation results clearly show that PGP-SELBOX NCFET is having reduced SCEs and 103 times better \(\frac {\mathrm {I}_{\text {ON}}}{\mathrm {I}_{\text {OFF}}}\) ratio over FDSOI NCFET. For optimized value of ferro-electric parameters average SS for proposed device is found as 50 mV/decade at tfe = 5nm which is lesser than FDSOI NCFET (56 mV/decade).

Retraction Note to: An analytical model for the effects of the variation of ferroelectric material parameters on the minimum subthreshold swing of NC-FETs

Retraction Note to: An analytical model for the effects of the variation of ferroelectric material parameters on the minimum subthreshold swing of NC-FETs

Ferroelectric Nanoparticles in a Nanocomposite. Influence of Size Distribution on Temperature Dependences of Pyroelectric and Electrocaloric Transformation

Ferroelectric materials are widely used in small micro- and nanoelectronic devices and systems, allowing for the pyroelectric and electrocaloric effects inherent to them. After the development of nanotechnology and the finding of finite-size effects, thin layers and nanocomposites, including ferroelectric, were developed and became widespread. Similarly, the theoretical studies and description of the ferroelectric nanocomposites are highly relevant. However, Theoretical studies in this direction have a number of difficulties, for example, in early works the influence of the depolarization field was not taken into account, and other works focused on calculations for nanocomposites with a constant radius of nanoparticles within the entire nanocomposite volume. Earlier, we analyzed the influence of the parameters of the truncated normal distribution function of the nanoparticle radius on the electrocaloric and pyroelectric characteristics of ferroelectric nanocomposites. However, the temperature dependences of the ferroelectric material parameters were not considered in this work. Since the pyroelectric and electrocaloric effects, which are inherent to ferroelectrics, are interrelated through the pyroelectric coefficient, elucidating the behavior of the temperature dependence of spontaneous polarization and its derivatives with changes in the parameters of polar-active composite materials is a priority for both experimental and theoretical studies.Using the Landau-Ginzburg-Devonshire theoretical approach for noninteracting ferroelectric single-domain spherical nanoparticles of different sizes placed in a dielectric matrix, the temperature dependences of spontaneous polarization, electrocaloric temperature change, pyroelectric and electrocaloric properties were calculated. Changes in the form of these dependences at different values of the parameters of the truncated normal distribution of nanoparticles by size - the most probable radius and dispersion - are analyzed.It is shown that the spontaneous polarization, parameters of maxima of pyroelectric and electrocaloric coefficients, and electrocaloric temperature change at the same value of their dispersion strongly depend on the most probable radius, and at the same value of the most probable radius weakly depend on the dispersion. The obtained results open a new possibility of controlling pyroelectric and electrocaloric parameters of ferroelectric nanocomposites through the nanoparticle size distribution parameters, which can be important for applications in energy converters and microcoolers.

Superior Performance of a Negative-capacitance Double-gate Junctionless Field-effect Transistor with Additional Source-drain Doping

In this work, we propose a negative-capacitance double-gate junctionless field-effect transistor (NC-JLFET) with additional source-drain doping for the first time. Superior performance of the NC-JLFET due to source and drain doping concentration is explained in detail. Additionally, the effects of the drain induced barrier lowering (DIBL) and negative differential resistance (NDR) are precisely analyzed in the NC-JLFET. Sentaurus TCAD simulation demonstrates that the additional source-drain-doped NC-JLFET exhibits a higher on/off current ratio ( I ON / I OFF ) and steeper subthreshold swing ( SS < 60 mV/dec) compared to a traditional JLFET. Besides, the negative capacitance effect causes the internal voltage of the gate to be amplified, resulting in negative DIBL and NDR phenomena. Finally, the performance of NC-JLFET can also be optimized by choosing suitable ferroelectric material parameters, such as ferroelectric thickness, coercive field, and remnant polarization. Our simulation study provides theoretical and experimental support for further performance improvement of low-power NCFETs by local structure adjustment.

Effect of different capacitance matching on negative capacitance FDSOI transistors

Negative capacitance field-effect transistors (NCFETs) have several advantages over traditional metal-oxide-semiconductor field-effect transistors (MOSFETs) and are considered to be promising technology for the next generation of integrated circuits nodes. In this study, an NCFET based on fully depleted silicon-on-insulator (FDSOI) technology is investigated using technology computer-aided design (TCAD) simulation. The effects of capacitance matching due to ferroelectric material parameters (coercive field Ec, remnant polarization Pr) on NCFET are discussed in detail. The simulation results show that good NCFET capacitance matching is closely related to the Pr to Ec ratio (RPE), a metric that is defined for the first time. In addition, it is observed that NCFETs with a two-layer ferroelectric structure can effectively adopt the capacitance matching in different operation regions, thereby increasing the on-state current and reducing the off-state current, resulting in higher switching current ratio (ION/IOFF) than the single-layer counterpart.

Cross-Domain Optimization of Ferroelectric Parameters for Negative Capacitance Transistors—Part I: Constant Supply Voltage

In this two-part article, we propose a framework for selecting ferroelectric oxide material for the design of a negative capacitance field-effect transistor (NCFET). The investigation is based on an exhaustive search of two important ferroelectric material parameters: remnant polarization and coercive field in the context of their negative capacitance properties. The effects of these parameters are first studied at the NCFET device level and systematically extended up to the full-chip level. Based on this search, we arrive at the notion of optimality of ferroelectric parameters for a given “isoperformance full-chip benchmark”: The power dissipation in a specific circuit/system is maximally reduced by using optimized NCFETs while meeting the target performance. In Part I, we develop the framework for identifying optimal ferroelectric parameters at a given ${V}_{\textsf {DD}}$ . This sets the stage for Part II, where we investigate the optimal ferroelectric parameters as ${V}_{\textsf {DD}}$ is scaled.

RETRACTED ARTICLE: An analytical model for the effects of the variation of ferroelectric material parameters on the minimum subthreshold swing of NC-FETs

The relationships between the coercive field (E C), remanent polarization (P 0), and thickness (t FE) of a ferroelectric material are derived analytically to determine the minimum subthreshold swing (S min) of a negative-capacitance field-effect transistor (NC-FET). The interdependence of the ferroelectric material properties is defined based on the capacitance matching condition in the subthreshold region of the NC-FET. An optimized combination of the parameters of the ferroelectric material in a gate stack is proposed to achieve transfer characteristics without hysteresis as well as lower subthreshold swing. The results are validated against numerical and experimental results available in literature. Furthermore, the minimum possible subthreshold swing (S min) is obtained for different ferroelectric materials used in the gate stack of an NC-FET in the context of a manufacturable semiconductor technology. The channel doping, ferroelectric thickness, and minimum subthreshold are calculated for five different ferroelectric materials.

Superior Performance and Reliability of Double Gate Gaussian Doped Negative Capacitance Junctionless Transistor for 200–500 K

ABSTRACT In this work, performance of Double Gate Gaussian Doped Negative Capacitance Junctionless Transistor (DGGDNCJLT) has been studied for temperature range 200–500 K to explore the suitability of the device for applications which demand operation at extended temperature range. The device behavior has been studied by using temperature dependent Landau parameters of ferroelectric material doped hafnium oxide with standard TCAD models. Further, to achieve improved device performance over a wide temperature range, ferroelectric material parameters have been optimized to enhance the impact of negative capacitance effect which consequently improves device characteristics. It has been demonstrated that even for a wide temperature range 200–500 K, DGGDNCJLT exhibits substantial improvement in gate controllability, I ON/I OFF ratio, subthreshold swing values less than 60 mV/dec and enhanced current drivability for optimized ferroelectric parameters.

Ferroelectric HfO2 Tunnel Junction Memory With High TER and Multi-Level Operation Featuring Metal Replacement Process

We have investigated device design of HfO2-based ferroelectric tunnel junction (FTJ) memory. Asymmetry of dielectric screening property in top and bottom electrodes is the key for high tunneling electroresistance (TER) ratio. Thus, metal and semiconductor electrodes are proposed. There exists a design space of ferroelectric material parameters to achieve high TER ratio under the constraint of depolarizing field. We have developed an FTJ fabrication process to realize the design. Large polarization charge and symmetric switching voltage are obtained by top metal replacement process. High TER ratio >30 and multi-level cell operation have been successfully demonstrated. Retention characteristics is promising, however, endurance characteristics should be improved for reliable operation.

Designing 0.5 V 5-nm HP and 0.23 V 5-nm LP NC-FinFETs With Improved ${I}_{ \mathrm{\scriptscriptstyle OFF}}$ Sensitivity in Presence of Parasitic Capacitance

Negative capacitance field effect transistor (NCFET) is designed in 5-nm FinFET node, which simultaneously meets the low-power and high-performance targets of ${I}_{ \mathrm{\scriptscriptstyle ON}}$ and ${I}_{ \mathrm{\scriptscriptstyle OFF}}$ at ${V}_{\sf dd}= 0.5$ V and ${V}_{\sf dd}= 0.23$ V, respectively, while the international roadmap for devices and systems (ITRS 2.0) projected ${V}_{\sf dd}$ is 0.65 V for both. The impact of power supply and parasitic capacitance on the performance of NCFET is studied. It is demonstrated that NCFET can be designed for fluid subthreshold swing (SS) behavior such that SS is degraded around ${V}_{\sf gs}=0$ , ${V}_{\sf ds}={V}_{\sf dd}$ , and is improved in the subthreshold region. This helps in combating OFF-current variation due to the threshold voltage fluctuations. A compact model to determine such design conditions is presented. Parasitic capacitance and the ferroelectric material parameters should be cooptimized for the target ${V}_{\sf dd}$ .

Compact Model for Ferroelectric Negative Capacitance Transistor With MFIS Structure

We present a physics-based compact model for a ferroelectric negative capacitance FET (NCFET) with a metal–ferroelectric–insulator–semiconductor (MFIS) structure. The model is computationally efficient, and it accurately calculates the gate charge density as a function of the applied voltages. For the first time, an explicit expression for the channel current in bulk NCFET is also deduced taking into account the spatial variation of ferroelectric polarization in the longitudinal direction. Using current continuity condition in the channel, we find that different regions of the ferroelectric may operate in a positive or a negative capacitance state depending on the external biases. The model captures the impact of ferroelectric thickness scaling and variation in the ferroelectric material parameters, and has been validated against the implicit approach involving full numerical computations as well as experimental data. We also compare the device characteristics of the MFIS structure with those of the metal–ferroelectric–metal–insulator–semiconductor structure.

Study on Uncooled Hybrid Focal Plane Detector Arrays

A thick film array of high sensitive UFPA detector, with 16×16 units, is described in this paper. A micromachining capacitive pixel structure of infrared detector is provided, with the doped (Ba, Sr) TiO3 (BST) thick film as sensitive material. The key factors that affect the detector performance are described, and the basic physical and electrical parameters of ferroelectric materials that the detector needs are given. In addition, the heat insulation technique and the corresponding parameters are provided. The capacitance increment of pixel for this structure is approximately equal to that of infrared detector with equivalent sensitive area, and then the parasitic capacitance between the pixel and substrate electrode lead is reduced. It is easy to design the integrated circuit because the infrared detector with this structure needs only low precision for the circuit. This design idea for array structure of infrared matches the development trend of structure design of infrared focal plane pixel with large array, which paves the way to develop new UFPA detector.

Interaction of a180°ferroelectric domain wall with a biased scanning probe microscopy tip: Effective wall geometry and thermodynamics in Ginzburg-Landau-Devonshire theory

The interaction of ferroelectric $180\ifmmode^\circ\else\textdegree\fi{}$-domain wall with a strongly inhomogeneous electric field of biased scanning probe microscope tip is analyzed within continuous Ginzburg-Landau-Devonshire theory. Equilibrium shape of the initially flat domain-wall boundary bends, attracts, or repulses from the probe apex, depending on the sign and value of the applied bias. For large tip-wall separations, the probe-induced domain nucleation is possible. The approximate analytical expressions for the polarization distribution are derived using direct variational method. The expressions provide insight into how the equilibrium polarization distribution depends on the wall finite width, correlation and depolarization effects, electrostatic potential distribution of the probe and ferroelectric material parameters.

The use of the Sawyer-Tower method and its modifications to measure the electrical parameters of ferroelectric materials

Modifications of the Sawyer-Tower method, based on a measurement of the impedance and Fourier transformations, are proposed. A functional and metrological analysis of the methods is presented, which enables the reliability of the measurements of the field dependences of the parameters of ferroelectric materials to be increased, which should find application in microelectronic and nanoelectronic products.