Search

Zero thermal expansion (ZTE) composites reinforced by negative thermal expansion (NTE) compounds exhibiting superior dimensional stability and high thermal conductivities, are urgently needed in the modern industrial field. Unfortunately, conventional strategies for achieving ZTE composites often compromise thermal conductivity by incorporating high-content NTE particles. This study reports an overlooked factor enhancing NTE: the in-situ thermal mismatch stresses within the composites, which provide a significant driving force for lattice distortion. The 50 vol.% Cu 2 P 2 O 7 /Al-Si composite achieves isotropic ZTE, low density, and high thermal conductivity due to pressure-enhanced NTE and a tight interface structure. Synchrotron X-ray diffraction and Density Functional Theory (DFT) calculations have revealed the key mechanism of in-situ residual thermal stress in the composite contributing to the enhancement of NTE in Cu 2 P 2 O 7. This work proposes a novel design approach for high-performance ZTE materials. A new strategy to enhance the negative thermal expansion (NTE) performance by using in-situ thermal residual stress within the composite material was proposed in this work. By adding a small amount of NTE reinforcement, the high expansion aluminum alloy can be transformed into zero expansion material. Such a strategy provides a promising method to obtain zero expansion material with low density and high thermal conductivity characteristics. [Display omitted] [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) room-temperature ferromagnetism is highly sought after for its great application potential but is challenged by chemical or magnetic structural instability. If room-temperature ferromagnetism can be realized in structurally stable 2D graphene, it will have a broad application prospect and market in flexible spintronics and wearable artificial intelligence. Although symmetry breaking such as vacancies, edges can introduce localized magnetic moments in intrinsically antimagnetic graphene, their weak coupling can only hold long-range ordering at low temperatures. Here, a robust ferromagnetic order has been observed in large-area graphene (centimeter scale) through mechanical folding and successive preprocesses of rapid cooling and heating method, where the Curie temperature of ∼6-layer graphene is close to 100 K and that of ∼10-layer graphene is above room temperature. We propose that the observed ferromagnetism is possibly attributed to the surface sp 3-type bonds emergent in the structure phase transition caused by strain effects. Intrinsic graphene cannot hold ferromagnetic order, although that is highly desired. In this work, a transition from paramagnetism to ferromagnetism is observed in copper-based graphene after mechanical folding with successive rapid cooling and heating process. Stress engineering in the wrinkled graphene is possible to promote the formation of sp 3-type bonds, which support the robust ferromagnetic order. [Display omitted] • A breakthrough in ferromagnetic 2-dimensional material for future flexible spintronics and artificial intelligence. • Overcoming the diamagnetism limitation of graphene, one of the most promising van der Waals materials. • A simple and effective method to introduce robust ferromagnetism in large area graphene. • Unveiling the crucial role of sp 2 to sp 3 C–C phase transition in maintaining graphene's robust ferromagnetic order. [ABSTRACT FROM AUTHOR]

Face-centred cubic (fcc-) Mo–N and Ta–N exhibit an inherent driving force for vacancy formation. To study their interaction and effects on structural evolution and mechanical properties, we synthesised Mo–Ta–N coatings by reactive magnetron sputtering using nitrogen-to-total pressure ratios, pN2/pT, of 0.32 and 0.69.Low pN2/pT results in high concentration of N vacancies, which stabilise single-phase fcc-Mo1-xTaxNy up to x = 0.76. These solid solutions follow the MoN0.5–Ta0.875N0.875 quasi-binary tie line. Compressive residual stresses, σ, indentation hardness, H, and toughness, KC, increase with Ta content, reaching their maxima of (on average) -2.0 GPa, 28 GPa, and 7.0 MPa√m, respectively, within the x range 0.38–0.69. Higher Ta contents favour higher concentration of metal vacancies deteriorating the properties.High pN2/pT favours the formation of fcc-Mo1-xTaxNy rich in metal vacancies, which however always coexists with a hexagonal phase. Within the x range 0.33–0.66, the fraction of the hexagonal phase is negligible, and σ, H, and KC deviate from −1.0 GPa, 28 GPa, and 2.9 MPa√m, respectively, within the error of measurements.The combination of experimental and theoretical studies demonstrates the power of point defects in stabilising desired crystal structures and improving mechanical properties through the thereby tuned atomic configuration.

Magnetic disclination, characterized by the orientation of domain-wall arrangement rotating by π along a closed loop, is a type of topological spin texture. This study demonstrates the creation of artificial magnetic disclination through local stress engineering. By patterning nanotrenches in permalloy/poly(methyl methacrylate) bilayers, the tensile stress is relieved in a directional manner through the formation of boundaries. This orients the domain distributions at the microscale through magnetoelastic coupling. Two-dimensional (2D) closed boundaries induce curved stripe domains, which are ultimately converted into disclinations. The geometric configuration and arrangement of the disclination can be spatially adjusted via 2D boundary designation. The combination of in-situ magnetic force microscopy and hysteresis loop measurements links the microscopic domain configuration to the macroscopic magnetic properties of the system. Simulations reveal that the magnetic disclination is critically dominated by the local stress distribution within the topographic confinement. [Display omitted] [ABSTRACT FROM AUTHOR]

• Various geometric structures to obtain strain-insensitivity are outlined. • Stress engineering methods for realizing strain insensitivity are discussed. • The principles for achieving strain insensitivity in material design are summarized. • A overview about representative strain-insensitive bioelectronics is presented. In recent years, the rapid advancement of wearable multifunctional bioelectronics has expanded the horizons of smart biomedical and healthcare applications. However, there is a pressing need for the development of multifunctional strain-insensitive bioelectronics due to the susceptibility of bioelectronics attached to the skin or tissues, which can lead to operational challenges and signal interference. Therefore, the pressing need to progress wearable health monitoring electronics hinges on the advancement of multifunctional strain-insensitive bioelectronics, with the goal of mitigating signal interference caused by deformations. This review offers a comprehensive exploration of the technologies and applications involved in achieving strain insensitivity in bioelectronics. First, the methods to mitigate signal interference resulting from deformation are discussed, encompassing geometric structural design, stress engineering, and material selection. Subsequently, we delve into specific applications that leverage these approaches in the realm of bioelectronic devices and beyond. Finally, a concise summary and discuss about the prospects and obstacles in this dynamic field are provided. This article serves as an effective solution to address the current demand for multifunctional strain-insensitive bioelectronics and offers inspiration for future endeavors in wearable electronics, health monitoring, and implantable medical devices. [ABSTRACT FROM AUTHOR]

Noninvasive tuning of the mechanical resonance frequencies of suspended parallel nanomembranes in various monolithic arrays is achieved by piezoelectric control of their tensile stress. Parametric amplification of their thermal fluctuations is shown to be enhanced by the piezoelectric actuation and amplification factors of up to 20 dB in the sub-parametric oscillation threshold regime are observed. [ABSTRACT FROM AUTHOR]

Abstract Hydrogenated diamond like carbon (a-C:H) coatings typically have low friction but high residual stress. The hardness which depends on the sp3 proportion increases not only the coating lifetime, but also the residual stress which can lead to easy film delamination especially for thick coatings. In this work, several thick a-C:H coatings (>10 μm) with different stress and hardness are prepared using stress engineering to mitigate stress accumulation while the hardness is retained. A low compressive residual stress of 0.42–0.84 GPa is achieved from the 8 μm thick a-C:H coating in addition to a high critical load of 63–74 N and hardness of over 26 GPa. The other desirable tribological and anticorrosion properties include a small friction coefficient of 0.13, low wear rate of 1.01 × 10−15 m3/N·m, high corrosion potential of - 479.6 mV, as well as small corrosion current density of 1.77 μA/cm2. Highlights • A universal meaning stress engineering method is proposed. • Low residual stress and high hardness of a-C:H coatings are achieved. • High adhesion up to 74 N are obtained in the a-C:H coatings. • The coatings also show excellent tribological and anti-corrosion properties. [ABSTRACT FROM AUTHOR]

Diffusion of atoms across the boundary between two bonding layers is the key for achieving excellent thermocompression Wafer on Wafer bonding. In this paper, we demonstrate a novel mechanism to increase the diffusion across the bonding interface and also shows the CMOS in-line process flow compatible Sub 100 °C Cu-Cu bonding which is devoid of Cu surface treatment prior to bonding. The stress in sputtered Cu thin films was engineered by adjusting the Argon in-let pressure in such a way that one film had a compressive stress while the other film had tensile stress. Due to this stress gradient, a nominal pressure (2 kN) and temperature (75 °C) was enough to achieve a good quality thermocompression bonding having a bond strength of 149 MPa and very low specific contact resistance of 1.5 × 10−8 Ω-cm2. These excellent mechanical and electrical properties are resultant of a high quality Cu-Cu bonding having grain growth between the Cu films across the boundary and extended throughout the bonded region as revealed by Cross-sectional Transmission Electron Microscopy. In addition, reliability assessment of Cu-Cu bonding with stress engineering was demonstrated using multiple current stressing and temperature cycling test, suggests excellent reliable bonding without electrical performance degradation. [ABSTRACT FROM AUTHOR]

The combined impact of process- and substrate-induced stress has been analyticallymodeled for a rectangular fin inserted into an insulator-on-silicon (IOS) substrate. Stress estimation and profiling are performed for different fractional insertion of the fin into the IOS substrate and the induced stress values are observed to saturate for ≥1/3 of the fin insertion. Therefore, a one-third of inserted Si fin is used to estimate the induced stress by following a standard FinFET process flow. Uniaxial compressive stress as high as 4.6 GPa has been obtained, and it has also been observed that the hole mobility can be enhanced to a significantly high value by judiciously choosing the gate dielectrics and fractional insertion of the fin. Thereby, the design of symmetric CMOS by using such mobility-enhanced p-FinFET is possible. Moreover, the current--voltage characteristics of such strain-engineered p-FinFETs exhibit improved drain-induced barrier lowering and subthreshold swing and ~45% enhancement of drain current. [ABSTRACT FROM AUTHOR]

Functionalized MXenes have attracted great interest due to their unique electrical, magnetic, optical, and electrochemical properties. In this paper, the effect of interlayer coupling on the electronic structures of Ti 2 CO 2 MXenes is investigated by using density functional theory. Due to the interlayer coupling, the band structures of Ti 2 CO 2 nanosheet are split, generating an indirect band gap of 0.869 eV, which is smaller than that of Ti 2 CO 2 monolayer (1.044 eV). Biaxial strain can be used to achieve the transitions of direct-indirect-negative band gaps semiconductor. The interlayer interaction effectively inhibits the structural changes under stress, resulting that the band gap of nanosheet be adjusted in a large stress range. Furthermore, the change trend of imaginary part ε 2 of the dielectric function indicates that stress has an obvious regulatory effect on the optical transition. The different responses of monolayer and nanosheet under stress provides more choice for the optical devices of Ti 2 CO 2 MXenes. [ABSTRACT FROM AUTHOR]

In this paper, we present an effective switching current model ( I\textsf {eff} ) for inverter followed by a transmission gate structure (Inv-Tx) based on its switching trajectory. Unlike an inverter or NAND/NOR gates, where I\textsf {eff} depends only on nMOSFET (pMOSFET) current for a falling (rising) transition, it is a function of both nMOSFET and pMOSFET currents for an Inv-Tx cell. The proposed model is verified against HSPICE simulations for a wide range of supply voltages and fan-outs at different technology nodes (e.g., 180, 130, and 65 nm). The model predicts the transition delay values with an average (maximum) error of 7% (11%) compared with HSPICE simulations. Synopsys TCAD Sentaurus simulations at 32-nm technology node are also used to validate the basic model assumptions. To demonstrate the utility of our model, design of some representative circuits while incorporating layout-dependent effects and inverse-narrow-width effect is presented. Finally, we show that a 256X1 multiplexer and a static D-flip-flop, with their transistor sizes and layout, optimized using the proposed model improves the performance of these circuits significantly over the conventional design methodologies. [ABSTRACT FROM PUBLISHER]

Alkoxide-derived lead zirconate titanate thin films having Zr/Ti = 50/50 to 60/40 compositions with different residual stress conditions were deposited on a Si wafer to clarify the effects of the residual stress on the morphotropic phase boundary shift. The residual stress condition was controlled to − 0.1 to − 0.9 GPa by the design of the buffer layer structure on the Si wafer. Results show that the maximum effective piezoelectric constant d 33 was obtained at 58/42 composition under − 0.9 GPa compressive residual stress condition. Moreover, the MPB composition shifted linearly to Zr-rich phase with increasing compressive residual stress. [ABSTRACT FROM AUTHOR]

Bandgap and stress engineering using group IV materials—Si, Ge, and Sn, and their alloys are employed to design a FinFET-based CMOS solution for the 7-nm technology node and beyond. A detailed simulation study evaluating the performance of the proposed design is presented. Through the use of a common strain-relaxed buffer layer for p- and n-channel MOSFETs and a careful selection of source/drain stressor materials, the CMOS design is shown to achieve performance benefits over strained Si, meet the $I_{{\rm OFF}}$ requirements, and provide a path for continued technology scaling. [ABSTRACT FROM PUBLISHER]

BiVO 4 is a promising and environmental-benign photoanode material. However, the photoelectrochemical properties of BiVO 4 are confined to its low charge separation efficiency. Herein, we have developed a simple method to introduce stress into the BiVO 4 photoanode via the change of the unit cell volume of VO 2 near the phase transition temperature. In this way, the crystal structure of BiVO 4 is caused to be distorted and thus improve the photoelectrochemical properties of the BiVO 4 photoanode, making the surface photopotential of the BiVO 4 -V photoanode nearly double that of the bare BiVO 4 photoanode. At room temperature, the photocurrent density of the BiVO 4 -V photoanode is 2.35 times that of the BiVO 4 photoanode. Intriguingly, at 85 °C, the photocurrent density of the BiVO 4 -V photoanode is as high as 6.8 times that of the BiVO 4 photoanode. Moreover, the photocurrent density of the BiVO 4 -V photoanode could reach 80% of the theoretical photocurrent density of the BiVO 4 photoanode at 85 °C in the presence of the sacrificial agent Na 2 SO 3. This work illustrates a new stress engineering strategy to improve the photoelectrochemical properties of BiVO 4 photoanodes and is expected to be applicable to other semiconductor photoanodes. [Display omitted] • The photoelectrochemical properties of BiVO 4 photoanode is largely improved by introducing VO 2. • The photocurrent density of the BiVO 4 -V photoanode can reach 80% of its theoretical photocurrent density at 85°C. • Upon stress introduction, the charge separation efficiency of BiVO 4 -V photoanode has been greatly improved. [ABSTRACT FROM AUTHOR]

Abstract: The interplay between the performance of nitride stress liner technologies and the contact metallization is studied based on computer simulations. Three dimensional models of transistor devices including the contacts have been created for the 32nm and 45nm technology nodes. The loss of stressor performance by opening the contact holes is studied systematically as function of the contact width. The use of strained contact metals to recover the performance loss due to metallization is demonstrated for nFET devices based on the simulation results. [Copyright &y& Elsevier]

The discovery of ferroelectricity and advances in creating polar structures in atomic-layered hafnia-zirconia (Hf x Zr 1- x O 2 ) films spur the exploration of using the material for novel integrated nanoelectromechanical systems (NEMS). Despite its popularity, the approach to achieving high quality factors ( Q s) in resonant NEMS made of Hf x Zr 1- x O 2 thin films remains unexplored. In this work, we investigate the realization of high Q s in Hf 0.5 Zr 0.5 O 2 nanoelectromechanical resonators by stress engineering via the incorporation of alumina (Al 2 O 3 ) interlayers. We fabricate nanoelectromechanical resonators out of the Hf 0.5 Zr 0.5 O 2 -Al 2 O 3 superlattices, from which we measure Q s up to 171,000 and frequency-quality factor products ( f × Q ) of >10 11 Hz through electrical excitation and optical detection schemes at room temperature in vacuum. The analysis suggests that clamping loss and surface loss are the limiting dissipation sources and f × Q > 10 12 Hz is achievable through further engineering of anchor structure and built-in stress.

The authors investigate the efficacy of applying rolling pressure along the weld line in thin butt welds produced using friction stir welding (FSW) as a means of controlling the welding residual stresses. Two cases are examined and in each case, comparison is made against the as welded condition. First, for FSW of AA 2024 aluminium alloy, roller tensioning was applied during welding using two rollers placed behind and either side of the FSW tool. Very little effect was seen for the down forces applied (0, 50, 75 kN). Second, for FSW AA 2199 aluminium alloy, post-weld roller tensioning was applied using a single roller placed directly on the FS weld line. In this case, significant effects were observed with increased loading, causing a marked reduction in the longitudinal tensile residual stress. Indeed, a load of just 20 kN was sufficient to reverse the sign of the weld line residual stress. Only slight differences in Vickers hardness were observed between the different applied loads. Furthermore, unlike some methods, this method is cheap, versatile and easy to apply. [ABSTRACT FROM AUTHOR]

Abstract: We use a two-band k · p Hamiltonian to describe the subband structure in strained silicon thin films. The model describes the dependence of the transversal effective mass on strain and film thickness. However, it is found that the two-band k · p model is unable to describe recently observed large valley splitting. Therefore a generalization of the model is necessary. To go beyond the k · p theory, an auxiliary tight-binding model defined on a lattice of sites containing two localized orbitals is introduced in such a way that it reproduces the bulk dispersion obtained from the two-band k · p model. Corresponding dispersion relations including strain are obtained. We discuss an alternative mechanism to create and control the valley splitting by applying shear strain. The valley splitting increases with increased shear strain and decreasing film thickness and can be larger than the spin splitting. This makes silicon-based quantum devices promising for future applications in quantum computing. [Copyright &y& Elsevier]

There is a trend towards miniaturization of silicon photonic circuits due to superior performance and small cost. Design rules that must be imposed on the geometry of optical waveguides to make them behave as polarization-independent and single-mode devices are well known for waveguides with relatively large cross sections and for some small cross-sectional rib waveguides with vertical sidewalls and an air top cladding. The influence of the top oxide cover on waveguide birefringence was analyzed recently, but only for relatively large cross-sectional waveguides. This paper reports simulations for both single-mode and polarization-independent behavior for small cross-sectional waveguides with variable rib width, etch depth, top oxide cover thickness, and side-wall angle. The results show that the stress-induced effects must be taken into account to satisfy both requirements. Design rules to maintain birefringence-free operation and to satisfy single-mode behavior for small rib silicon-on-insulator (SOI) waveguides are presented. [ABSTRACT FROM PUBLISHER]

The need to use 3D process simulation increases as device dimensions shrink and new 3D device designs emerge. Moreover, many state-of-the art CMOS devices employ some sort of stress engineering, which necessitates 3D stress simulations. To perform these simulations efficiently and quickly, new methodologies need to be employed. In this paper we demonstrate several applications of the next generation TCAD tools to 3D simulation problems critical for understanding and development of modern devices. [ABSTRACT FROM AUTHOR]

We demonstrate that stress engineering is an effective tool to modify or eliminate polarization dispersion in silicon-on-insulator (SOI) waveguide devices, for a wide range of waveguide cross-section shapes and dimensions. The stress-induced effects on the modal birefringence of SOI waveguides are investigated numerically and experimentally. Finite-element simulations show that while the birefringence of ridge waveguides with both slanted and vertical sidewalls can be effectively modified using cladding stress, the birefringence becomes much less sensitive to dimension fluctuations with decreasing sidewall slope. To efficiently simulate the stress-induced effects we propose a normalized plane-strain model which can achieve comparable accuracy as a fully generalized plane-strain model but requires significantly less computational resources. Excellent agreement is achieved between the calculated and measured birefringence tuning using SiO2 cladding induced stress. Finally, both calculations and experiments confirm that cladding induced stress can be used to eliminate the birefringence in SOI waveguides of arbitrary shapes, for typical SiO2 film stress values (σfilm≍-100 to -300 MPa) and cladding thicknesses of the order of 1 μm or less. [ABSTRACT FROM PUBLISHER]

In the quest for highly scalable and three-dimensional (3D) stackable memory components, ferroelectric tunnel junction (FTJ) crossbar architectures are promising technologies for nonvolatile logic and neuromorphic computing. Most FTJs, however, require additional nonlinear devices to suppress sneak-path current, limiting large-scale arrays in practical applications. Moreover, the giant tunneling electroresistance (TER) remains challenging due to their inherent weak polarization. Here, we present that the employment of a diffusion barrier layer as well as a bottom metal electrode having a significantly low thermal expansion coefficient has been identified as an important way to enhance the strain, stabilize the ferroelectricity, and manage the leakage current in ultrathin hafnia film, achieving a high TER of 100, negligible resistance changes even up to 10 8 cycles, and a high switching speed of a few tens of nanoseconds. Also, we demonstrate that the usage of an imprinting effect in a ferroelectric capacitor induced by an ionized oxygen vacancy near the electrode results in highly asymmetric current-voltage characteristics with a rectifying ratio of 1000. Notably, the proposed FTJ exhibits a high density array size (>4k) with a securing read margin of 10%. These findings provide a guideline for the design of high-performance and selector-free FTJ devices for large-scale crossbar arrays in neuromorphic applications.

Face-centred cubic (fcc-) Mo–N and Ta–N exhibit an inherent driving force for vacancy formation. To study their interaction and effects on structural evolution and mechanical properties, we synthesised Mo–Ta–N coatings by reactive magnetron sputtering using nitrogen-to-total pressure ratios, p N2 / p T , of 0.32 and 0.69. Low p N2 / p T results in high concentration of N vacancies, which stabilise single-phase fcc-Mo 1- x Ta x N y up to x = 0.76. These solid solutions follow the MoN 0.5 –Ta 0.875 N 0.875 quasi-binary tie line. Compressive residual stresses, σ , indentation hardness, H , and toughness, K C , increase with Ta content, reaching their maxima of (on average) -2.0 GPa, 28 GPa, and 7.0 MPa√m, respectively, within the x range 0.38–0.69. Higher Ta contents favour higher concentration of metal vacancies deteriorating the properties. High p N2 / p T favours the formation of fcc-Mo 1- x Ta x N y rich in metal vacancies, which however always coexists with a hexagonal phase. Within the x range 0.33–0.66, the fraction of the hexagonal phase is negligible, and σ , H , and K C deviate from −1.0 GPa, 28 GPa, and 2.9 MPa√m, respectively, within the error of measurements. The combination of experimental and theoretical studies demonstrates the power of point defects in stabilising desired crystal structures and improving mechanical properties through the thereby tuned atomic configuration. [Display omitted] • Experimental and first principle insights into the barely explored MoN–TaN. • Magnetron sputtered MoN–TaN films with a wide composition range. • Role of vacancies in favouring the cubic structure over other polymorphs. • 140% toughness enhancement through cubic-structured Mo 1- x Ta x N y solid solutions realised by nitrogen vacancies. [ABSTRACT FROM AUTHOR]

MoS2 is a promising candidate for hydrogen evolution reaction (HER), while its active sites are mainly distributed on the edge sites rather than the basal plane sites. Herein, a strategy to overcome the inertness of the MoS2 basal surface and achieve high HER activity by combining single-boron catalyst and compressive strain was reported through density functional theory (DFT) computations. The ab initio molecular dynamics (AIMD) simulation on B@MoS2 suggests high thermodynamic and kinetic stability. We found that the rather strong adsorption of hydrogen by B@MoS2 can be alleviated by stress engineering. The optimal stress of −7% can achieve a nearly zero value of ΔGH (~ −0.084 eV), which is close to that of the ideal Pt-SACs for HER. The novel HER activity is attributed to (i) the B-doping brings the active site to the basal plane of MoS2 and reduces the band-gap, thereby increasing the conductivity; (ii) the compressive stress regulates the number of charge transfer between (H)-(B)-(MoS2), weakening the adsorption energy of hydrogen on B@MoS2. Moreover, we constructed a SiN/B@MoS2 heterojunction, which introduces an 8.6% compressive stress for B@MoS2 and yields an ideal ΔGH. This work provides an effective means to achieve high intrinsic HER activity for MoS2. [ABSTRACT FROM AUTHOR]

The formation of ordered magnetic domains in thin films is important for the magnetic microdevices in spin-electronics, magneto-optics, and magnetic microelectromechanical systems. Although inducing anisotropic stress in magnetostrictive materials can achieve the domain assembly, controlling magnetic anisotropy over microscale areas is challenging. In this work, we realized the microscopic patterning of magnetic domains by engineering stress distribution. Deposition of ferromagnetic thin films on nanotrenched polymeric layers induced tensile stress at the interfaces, giving rise to the directional magnetoelastic coupling to form ordered domains spontaneously. By changing the periodicity and shape of nanotrenches, we spatially tuned the geometric configuration of domains by design. Theoretical analysis and micromagnetic characterization confirmed that the local stress distribution by the topographic confinement dominates the forming mechanism of the directed magnetization.

Abstract: Effect of the thermal expansion coefficient of electrode on the electrical properties in lead zirconate titanate (PZT) with morphotropic phase boundary (Pb(Zr0.53,Ti0.47)O3: MPB) composition film was demonstrated in this paper. The lanthanum nickel oxide (LaNiO3: LNO) and lanthanum strontium cobalt oxide ((La0.5,Sr0.5)CoO3: LSCO) was deposited by chemical solution deposition (CSD) as bottom electrode on Si wafer. Highly (100)-oriented LSCO layers were successfully prepared by CSD on Si wafer using (100)-oriented LNO layers as seeding layer for the crystal orientation control. As a result, (100) and (001) oriented PZT film was also successfully prepared on LSCO/LNO/Si stacking structure. The obtained dielectric and ferroelectric properties changed according to the thermal stress which was influenced by the bottom electrode thickness. [Copyright &y& Elsevier]

A model for stress-induced effective hole mobility enhancement in (110) / (001) bulk pMOSFETs is presented. The model is based on first-and second-order stress-dependent piezo-conductance coefficients and considers the symmetry reduction compared to bulk silicon induced by surface scattering at the gate interface. The piezoconductance coefficients are determined by Monte Carlo (MC) device simulation for five particular stress configurations with a maximum stress level of 3 GPa. Finally, comparisons between MC simulations and the new mobility model for general stress configurations show a good agreement thus validating the new approach. [ABSTRACT FROM AUTHOR]

Bulk pMOSFET performance enhancement by combinations of SiGe pockets, compressively stressed cap liner and (110) surface orientation is investigated by mechanical stress and Monte Carlo device simulation. In agreement with recent measurements, the on-current gain by a (110) surface orientation of the 45 nm pMOSFET with a 3 GPa compressive cap liner is 32% and 16% without and with the presence of Si0.8Ge0.2 pockets, respectively. However, the performance enhancement by a (110) surface orientation strongly decreases upon scaling and for increasing liner stress. This suggests that the enhanced mobility for (110) surface orientation may lose its advantage in the limit of further scaling and increasing stress. [ABSTRACT FROM AUTHOR]

In this letter, mobility improvements by stress contact etch stop layer (CESL) in a strained 90-nm nMOSFET, with and without notched-gate structure, were studied in detail. Compared to the conventional vertical gate, a device with notched gate shows an extra 7% NMOS ION enhancement for the increased stress in the channel region and the less effect of the halo-implanted impurity on channel. Both simulations with TCAD software and measurements confirm that the notched-gate structure efficiently enhances the generation of high tensile stress on the channel region from the CESL and more localized pocket implant. [ABSTRACT FROM AUTHOR]