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In the pursuit of advancing neuromorphic computing, our research presents a novel method for generating and precisely controlling intermediate states within heavy metal/ferromagnet systems. These states are engineered through the interplay of a strong in-plane magnetic field and an applied charge current. We provide a method for fine-tuning these states by introducing a small out-of-plane magnetic field, allowing for the modulation of the system's probabilistic response to varying current levels. We also demonstrate the implementation of a spiking neural network (SNN) with a tri-state spike timing-dependent plasticity (STDP) learning rule using our devices. Our research furthers the development of spintronics and informs neural system design. These intermediate states can serve as synaptic weights or neuronal activations, paving the way for multi-level neuromorphic computing architectures. [ABSTRACT FROM AUTHOR]

Topological materials have shown promising potential in the spintronics application due to their conspicuous efficiency of charge-to-spin conversion. Our research investigates the temperature-dependent spin–orbit torque (SOT) from sputtered WTex. We reveal a strong temperature dependence of SOT and realize the current-induced SOT switching of WTex with perpendicular magnetic anisotropy structure under a wide range of 12 K to room temperature. Our findings reveal the temperature dependence of sputtered WTex and may pave the way for the spintronics application of semimetals under cryogenic temperature. [ABSTRACT FROM AUTHOR]

Lock-in carrierography (LIC), a recently emerging camera-based imaging technique, is proving to be very promising for noncontact and quantitative characterization of electrical/electronic properties of semiconductor and optoelectronic materials/devices at different stages of research, fabrication, and manufacturing. This tutorial is devoted to LIC and it contains four sections. First, the background of the terminology, the needs from the electronics industry, and the research progress of LIC are briefly introduced. Section II is regarding homodyne LIC, including the relevant basics (semiconductor and photoluminescence physics, digital lock-in imaging strategy, experimental configuration, etc.) and its applications to carrier effective lifetime imaging, resistivity imaging, and Si solar cell electrical characterization, while Sec. III is for heterodyne LIC, including the relevant basics (high-frequency carrier density waves, heterodyne photoluminescence signal generation mechanisms, nonlinear carrier recombination dynamics, etc.) and its applications to surface recombination velocity imaging, carrier trapping dynamic parameters imaging, and quantum-dot solar cell characterization. Comments and advice on the future study of LIC are given in the Outlook section. [ABSTRACT FROM AUTHOR]

The surface recombination velocity (SRV), which reflects the fundamental characteristics of surface defects of semiconductor wafers, is an important parameter in evaluating the quality of surface passivation and electrical performance of surface devices. In conventional photocarrier radiometry (PCR) used for characterizing the electronic transport properties of electronically thick silicon wafers, the rear SRV usually cannot be determined directly due to the relatively low sensitivity of PCR signal to the rear SRV. On the other hand, the determination of front SRV is also very sensitive to the experimental measurement error, especially the measurement error of instrumental frequency response, which is not always easy to be accurately measured in the experiment. In this paper, the front and rear SRVs of silicon wafers are extracted simultaneously with high accuracy by a differential PCR via multi-parameter fitting of the experimental frequency dependences of amplitude ratio and phase difference of PCR signals obtained from the regular measurements and measurements with wafers being flipped respectively to a corresponding differential nonlinear PCR model. The comparison between the front and rear SRVs determined by the conventional and differential PCRs indicates that the differential PCR is highly accurate for the simultaneous determination of the front and rear SRVs of silicon wafers. [ABSTRACT FROM AUTHOR]

Micro-grained diamond-SiC composites have been prepared by sintering a mixture of micro-grained diamond and Si powder using high-temperature and high-pressure method at 1100–1500 ° C , and 5.5 GPa. Plate impact experiments in reverse—and forward—impact geometry were used to investigate the shock response of the micro-grained diamond-SiC composites within a shock pressure range from 22 to 195 GPa. The obtained plot of shock velocity (D) vs particle velocity (u) indicated that the double elastic wave responses are observed in the pressure range of 22–170 GPa, which is consistent with the previously reported diamond-SiC composites containing a small amount of tungsten carbide (WC) under shock compression up to ∼ 110 GPa [Li et al., J. Appl. Phys. 128, 245901 (2020)]. The results of shock experiments demonstrate that the Hugoniot elastic limit of micro grained diamond in SiC matrix is as high as 170 GPa, which is nearly twice as high as that of single crystal diamond. [ABSTRACT FROM AUTHOR]

The perpendicular shape anisotropy-spin transfer torque-magnetic random access memories (PSA-STT-MRAMs) take advantage of the nanopillar free-layer geometry for securing a good thermal stability factor from the shape anisotropy of the nanomagnet. Such a concept is particularly well-suited for small junctions down to a few nanometers. At such a volume size, the nanopillar can be effectively modeled as a Stoner–Wohlfarth particle, and the shape anisotropy scales with the spontaneous magnetization by ∼ M s 2. For almost all ferromagnets, M s is a strong function of temperature; therefore, the temperature-dependent shape anisotropy is an important factor to be considered in any modeling of the temperature-dependent performance of PSA-STT-MRAMs. In this work, we summarize and discuss various possible temperature-dependent contributions to the thermal stability factor and coercivity of the PSA-STT-MRAMs by modeling and comparing different temperature scaling and parameters. We reveal nontrivial corrections to the thermal stability factor by considering both temperature-dependent shape and interfacial anisotropies. The coercivity, blocking temperature, and electrical switching characteristics that resulted from incorporating such a temperature dependence are also discussed, in conjugation with the nanomagnet dimension and coherence volume. [ABSTRACT FROM AUTHOR]

The geometric and electronic properties of the double-walled nanotubes (DWNTs), constructed by the two coaxial single-walled nanotubes (SWNTs) rolling the hexagonal titanium dioxide (TiO2) nanosheet along with the armchair (ac-) and the zigzag (zz-) directions, have been investigated systematically using the methods based on the density functional theory. For the optimized structures, the bandgap values of the TiO2 DWNTs are significantly reduced from that of the constituent SWNTs, falling in the visible light range. Further detailed analysis reveals that the reduction is caused by the band misalignment due to the different curvatures of the inner and outer TiO2 SWNTs. [ABSTRACT FROM AUTHOR]

In this work, a low-loss As2S5 optical fiber with 0.1 dB/m at 1545 nm was designed and fabricated, whose residual birefringence provided an opportunity for investigating the polarization modulation instability (PMI). Using a nanosecond laser operated at ∼1545 nm as the pump source, PMI and the stimulated Raman scattering (SRS) were experimentally investigated in a 3 m As2S5 optical fiber. During the SRS process, the amplified CW signal at 1632 nm and 1633 nm induced the PMI. To the best of our knowledge, this is the first report on the PMI effect induced by the amplified signal in the first-order SRS. The PMI gain was measured to be 24.4 dB at the signal of 1551 nm with the pump power of 20 mW, and the Raman gain was measured to be 31.2 dB at the signal of 1632 nm with the pump power of 41 mW. This investigation on the PMI gain and Raman gain in the As2S5 optical fiber may provide a reference for the development of fiber amplifiers, fiber lasers, and optical communication. [ABSTRACT FROM AUTHOR]

A nonlinear photocarrier radiometry (PCR) based quantitative defect characterization method is applied to determine the electronic transport parameters of the implantation layer of B+ ion-implanted silicon wafers with different implantation doses. A rigorous two-layer nonlinear PCR model is employed to fit the experimental modulation frequency dependences of PCR amplitude and phase to determine the transport parameters, that is, the carrier lifetime, carrier diffusion coefficient, and front surface recombination velocity of the implantation layer via multiparameter fitting. In the multiparameter fitting, the effects of the implantation layer thickness determination on the extraction of the electronic transport properties of the implantation layer are discussed via setting the thickness as a free parameter in the multiparameter fitting and fixed parameters determined by Monte Carlo based TRIM calculation. The fitted implantation layer thicknesses are in good agreement with that determined via TRIM calculation with a modified electronic damage threshold. Monotonic dependences of the transport properties of the implantation layers on the implantation dose are observed, and the effects of impurity density on the transport properties of the implantation layers are discussed. Good agreements between the experimental implantation dose dependence of the nonlinearity coefficient and corresponding theoretical calculations with the determined transport parameters are obtained. These results show that the two-layer nonlinear PCR model is accurate for quantitatively characterizing the transport properties and thickness of the ion-implantation layers of silicon wafers, and the nonlinear PCR technique is appropriate for precise defect characterization in the semiconductor manufacturing processes. [ABSTRACT FROM AUTHOR]

Simulations were carried out to study the uniqueness range of Heterodyne Lock-in Carrierography (HeLIC) imaging measurements of carrier transport parameters (bulk lifetime, diffusion coefficient, and front and back surface recombination velocities) of silicon wafers. Theoretically, HeLIC can resolve all four transport parameters; however, in practice, the presence of experimental noise does not allow all those parameters to be measured reliably and uniquely from HeLIC images alone. An extended range of simultaneously determined unique transport parameters was attained through the combination of HeLIC camera pixel and photocarrier radiometry (PCR) experimental frequency response data via a multi-parameter fitting procedure. Two n- and p-type wafers with different surface recombination velocities were used to illustrate the simulation results. Quantitative HeLIC images of diffusion coefficients and surface recombination velocities were obtained, with bulk lifetime values determined from PCR frequency scan measurements. The combined approach was shown to be able to resolve all four transport parameters uniquely and thus reliably. [ABSTRACT FROM AUTHOR]

We propose a thin-film Ge-on-Si-on-insulator (Ge-on-SOI) photodetector with enhanced performance by exploiting induced guided mode resonance (GMR) employing Ge/SiO2 grating on Si-on-insulator (SOI). Numerically calculated results and theoretical analysis demonstrate that normal-incidence light can be coupled to the GMR and partly be converted into the spatial resonance mode which propagates along the whole properly designed grating structure. A notable absorption efficiency of higher than 70% is obtained in the photodetector with only 280 nm-thick Ge/SiO2 grating, which is about 35 times larger than that of the counterpart without the designed grating structure. Remarkable enhanced light absorption can be achieved in the device with very few grating periods, which signifi- cantly promotes a theoretical 3-dB bandwidth-efficiency product of ~66GHz. The result is promising for a compact Ge-on-Si photodetector design with low dark current, high-bandwidth, and highresponsivity. [ABSTRACT FROM AUTHOR]

We propose a thin-film Ge-on-Si-on-insulator (Ge-on-SOI) photodetector with enhanced performance by exploiting induced guided mode resonance (GMR) employing Ge/SiO2 grating on Si-on-insulator (SOI). Numerically calculated results and theoretical analysis demonstrate that normal-incidence light can be coupled to the GMR and partly be converted into the spatial resonance mode which propagates along the whole properly designed grating structure. A notable absorption efficiency of higher than 70% is obtained in the photodetector with only 280 nm-thick Ge/SiO2 grating, which is about 35 times larger than that of the counterpart without the designed grating structure. Remarkable enhanced light absorption can be achieved in the device with very few grating periods, which significantly promotes a theoretical 3-dB bandwidth-efficiency product of ∼66 GHz. The result is promising for a compact Ge-on-Si photodetector design with low dark current, high-bandwidth, and high-responsivity. [ABSTRACT FROM AUTHOR]

When the grain size decreases, there inevitably exists a critical size (dc) where the contribution of surface atoms to the physical properties is competitive with that of the interior atoms, giving rise to a wide variety of new phenomena. The behavior of granular materials near dc is particularly interesting because of the crossover, a continuous transition from one type of mechanism to another. In situ high-pressure x-ray diffraction experiments showed that the compression curve of nanocrystalline anatase TiO2 with grain size near dc reached a platform after about 5%–6% of deformation under hydrostatic compression. Eventually, the unit cell volume of anatase expanded at ~14–16 GPa. We propose that the anomalous compression behavior is attributed to the formation and thickening of the stiff high density amorphous shell under high pressure, giving rise to a great arching effect at the grain boundary at the nanolevel. This process results in a remarkable difference in stress between inside and outside of the shell, generating the illusions of the hardening and the negative compressibility. This study offers a new insight into the mechanical properties of nanomaterials under extreme conditions. [ABSTRACT FROM AUTHOR]

When the grain size decreases, there inevitably exists a critical size (dc) where the contribution of surface atoms to the physical properties is competitive with that of the interior atoms, giving rise to a wide variety of new phenomena. The behavior of granular materials near dc is particularly interesting because of the crossover, a continuous transition from one type of mechanism to another. In situ high-pressure x-ray diffraction experiments showed that the compression curve of nanocrystalline anatase TiO2 with grain size near dc reached a platform after about 5%–6% of deformation under hydrostatic compression. Eventually, the unit cell volume of anatase expanded at ~14–16 GPa. We propose that the anomalous compression behavior is attributed to the formation and thickening of the stiff high density amorphous shell under high pressure, giving rise to a great arching effect at the grain boundary at the nanolevel. This process results in a remarkable difference in stress between inside and outside of the shell, generating the illusions of the hardening and the negative compressibility. This study offers a new insight into the mechanical properties of nanomaterials under extreme conditions. [ABSTRACT FROM AUTHOR]

A detailed analysis on the morphological evolution and strain relaxation of nanoscale Ge islands on SiO2-covered Si is presented to identify the mechanisms by which the high-quality epilayers forms. The immobility of Ge islands gives rise to a unique bimodal size distribution during coarsening.

Research was conducted to examine the nonlinear peizoelectric behavior of ceramic bending mode actuators under strong electric fields. Linear relationships between actuator tip displacement-electric field and blocking force-electric field were found to be only valid under weak field driving under quasistatic condition. The mechanical quality factor of actuators was dependent on driving field. No significant temperature increase was observed when actuators were driven at resonance frequency under high electrical field.

We investigated the relationship between the fine structure of spin-coated conductive polymer poly(3,4-ethylenedioxythiphene):poly(styrene sulfonate) (PEDOT:PSS) films and the photovoltaic performance of PEDOT:PSS crystalline-Si (PEDOT:PSS/c-Si) heterojunction solar cells. Real-time spectroscopic ellipsometry revealed that there were two different time constants for the formation of the PEDOT:PSS network. Upon removal of the polar solvent, the PEDOT:PSS film became optically anisotropic, indicating a conformational change in the PEDOT and PSS chain. Polarized Fourier transform infrared attenuated total reflection absorption spectroscopy and Raman spectroscopy measurements also indicated that thermal annealing promoted an in-plane π-conjugated Cα=Cβ configuration attributed to a thiophene ring in PEDOT and an out-of-plane configuration of -SO3 groups in the PSS chain with increasing composition ratio of oxidized (benzoid) to neutral (quinoid) PEDOT, Iqui/Iben. The highest power conversion efficiency for the spin-coated PEDOT:PSS/c-Si heterojunction solar cells was 13.3% for Iqui/Iben=9-10 without employing any light harvesting methods. [ABSTRACT FROM AUTHOR]

We present a systematic study of the geometric, electronic, and magnetic properties of hematite nanoribbons (α-Fe2O3NRs) using density functional theory. The hematite nanoribbons were generated by cutting atomically thin hematite nanosheets from the (110) and (104) surfaces along their [100] and [010] directions. All nanoribbon types are energetically feasible to synthesize. Nanoribbons obtained from the (110) surface show definite tunable semiconducting character. One type of nanoribbons obtained from the (104) surface shows surface modifications or bending nature indicating pseudo-Jahn-Teller effect, while the other type showed built-in oxygen vacancy on one edge despite preserving the stoichiometry, wherein the built-in oxygen vacancy introduces a halfmetallicity into the nanoribbons at larger widths. The results indicate that α-Fe2O3NRs with the appropriate width and type are promising future materials in solar energy conversions and spintronics-based devices. [ABSTRACT FROM AUTHOR]

ErSi1.7 layers with high crystalline quality were produced by 90 keV Er ion implantation employing channeled implantation. The perpendicular and parallel elastic strain of the heteroepitaxial erbium silicide layers were obtained with symmetric and asymmetric x-ray reflections utilizing a double-crystal x-ray diffractometer. The quasipseudomorphic growth of the epilayer and the stiffness along a and c axes of epilayer were deduced from the x-ray diffraction.

The temperature-dependence coefficient of Brillouin frequency shift (BFS) in perfluorinated graded-index polymer optical fibers is known to change drastically, because of the glass transition, at a certain critical temperature (Tc), above which the BFS becomes more sensitive to temperature. In this paper, we demonstrate that the Tc value can be adjusted by varying the dopant concentration, which is originally used to form the graded-index profile in the core region. Furthermore, we show that the temperature sensitivity of the BFS is enhanced in the presence of dopant probably because the temperature sensitivity of Young's modulus is increased. The results indicate a big potential of the temperature sensors based on Brillouin scattering with an extremely high sensitivity in a specific desired temperature range. [ABSTRACT FROM AUTHOR]

Based on density functional theory, the electronic structures, formation energy, and transition level of the selected group V and VII impurities in α-Fe2O3 are investigated by means of first-principles methods. Numerical results show that the group V and VII atoms-doped α-Fe2O3 can be energetically favorable under the Fe-rich condition. Group V atom substituting O atom can induce the acceptor impurity level, while the deep donor impurity states are formed inside the band gap when group VII atom substitute O atom in the α-Fe2O3. Moreover, our results show that halogen atom F substituting O atom should be very easy in the α-Fe2O3. In addition, our results also show that for both group V and VII atom-doped α-Fe2O3, the upper sides of valence band are modified obviously, while the conduction band edge does not change. [ABSTRACT FROM AUTHOR]

Investigation of the equation of state of molybdenum diboride (MoB2) has been performed to 24.1GPa using synchrotron radiation angle-dispersive x-ray diffraction techniques (ADXRD) in a diamond anvil cell (DAC) at room temperature. Rietveld refinement of the X-ray powder diffraction data reveals that the rhombohedral structure MoB2 is stable up to 24.1GPa. The ADXRD data yield a bulk modulus K0 = 314(11)GPa with a pressure derivative K'0 = 6.4(1.5). The experimental data are discussed and compared to the results of first-principles calculations. In addition, the compressibility of the unit cell axes (a and c axes) of MoB2 demonstrates an anisotropic property with pressure increasing. [ABSTRACT FROM AUTHOR]

Angle-dispersive synchrotron X-ray diffraction measurements were performed on vaterite-type YBO3/Eu3+, GdBO3, and EuBO3, respectively, up to 41GPa at room temperature using a diamond-anvil cell. Pressure-induced amorphization was observed in hexagonal GdBO3 with a significant compression along the c-axis. Compared to the ions of the distorted GdBO3 phase, its anions may lose their long-range order prior to the cations at high pressures. Based on the experimental pressure-volume data, the obtained bulk moduli of YBO3/Eu3+, GdBO3, are 329 and 321GPa, respectively, which are more than 90% larger than that of EuBO3 (167GPa) and are presumably attributed to Gd3+ and Y3+ with a high density of d valence electrons. [ABSTRACT FROM AUTHOR]

Silicon wafer bonding during annealing was modeled.

A model to describe the elastic deformation of water surfaces in bonding is proposed.

The spontaneous emission of polarized excitons in GaInP/AIGaInP surface emitting lasers was studied.

An observation of quantum-confined redshift in SiGe/Si type -I MQWs by photocurrent spectroscopy is presented. The bias dependence of the spectra suggests a Stark redshift below a certain electric field.

Room temperature photoluminescence (PL) was observed along 50 μm long Ge strips on insulator on bulk Si substrates fabricated by rapid melt growth. The PL peaks evidently exhibited a redshift from the origin to the end of the Ge strip because of the shrinkage of the direct bandgap of Ge. Moreover, PL intensities increased along the direction of lateral epitaxial growth primarily because of the decrease in the energy difference between the direct and indirect gaps of Ge. The change in the Ge band structure, which facilitated changes in PL peaks and intensities, was found to have resulted from the variation of tensile strain ratios and Si fractions along Ge strips. Furthermore, the PL intensity at the end of the strip was one magnitude higher than that of bulk Ge, which indicates the high quality of Ge-on-insulator structures. [ABSTRACT FROM AUTHOR]

Pure-phase polycrystalline cadmium tetraphosphide (CdP4) has been successfully synthesized under high pressures in a large volume cubic press, and the pressure-temperature (P-T) formation boundary of CdP4 from the Cd-P binary system has been determined. The equation of state of monoclinic CdP4 has also been evaluated by synchrotron-radiation angle-dispersive X-ray diffraction (ADXRD) under quasihydrostatic compression up to 26.4 GPa in a diamond-anvil cell. The ADXRD data yield a bulk modulus B0 = 94 ± 9 GPa with a pressure derivative B0′ = 8.0. The experimental data are discussed and compared to the results of first-principles calculations. [ABSTRACT FROM AUTHOR]

The n-type doping in the cuprous oxide (Cu2O) synthesized from an acidic solution environment has been studied by the first-principles calculations. The dopants of F, Cl, and Br in substitution of an O atom have low formation energies. They present an n-type conduction behavior with donor levels below but close to the bottom of the conduction bands. The Cl dopant has the shallowest donor level among the three halogens. The results are in good agreement with the very recent experimental results. [ABSTRACT FROM AUTHOR]

Ionic electroactive polymer (IEAP) actuators containing porous conductive network composites (CNCs) and ionic liquids can result in high strain and fast response times. Incorporation of spherical gold nanoparticles in the CNC enhances conductivity and porosity, while maintaining relatively small thickness. This leads to improved mechanical strain and bending curvature of the actuators. We have employed the layer-by-layer self-assembly technique to fabricate a CNC with enhanced curvature (0.43 mm-1) and large net intrinsic strain (6.1%). The results demonstrate that curvature and net strain of IEAP actuators due to motion of the anions increase linearly with the thickness of the CNC as a result of the increased volume in which the anions can be stored. In addition, after subtracting the curvature of a bare Nafion actuator without a CNC, it is found that the net intrinsic strain of the CNC layer is independent of thickness for the range of 20-80 nm, indicating that the entire CNC volume contributes equivalently to the actuator motion. Furthermore, the response time of the actuator due to anion motion is independent of CNC thickness, suggesting that traversal through the Nafion membrane is the limiting factor in the anion motion. [ABSTRACT FROM AUTHOR]

We propose a coupled surface plasmon (SP) interference lithography based on a metal-bounded dielectric structure. The long and short range SP interferences at different dielectric thicknesses in the structure are analyzed. The interference in Kretschmann structure under the same conditions is also compared. Numerical results show the coupled SP interference offers better lithography performance as compared with the Kretschmann SP interference. This proposed technique provides potential for fabrication of periodic nanostructures. [ABSTRACT FROM AUTHOR]

The formation of native point defects in cuprous oxide, Cu2O, synthesized from solution has been studied by first-principles calculations. Although p-type conduction is obtained in Cu2O synthesized from vacuum regardless of copper-rich or oxygen-rich conditions, intrinsically n-type Cu2O without doping can be grown in a strong acidic environment from solution. Our calculations show that both n-type and p-type Cu2O can be obtained depending on the solution pH value, which are in good agreement with our experimental results. [ABSTRACT FROM AUTHOR]

Enhancement of weak and high field dielectric responses was observed in poly(vinylidene fluoride) terpolymer/ZrO2 nanocomposites. A frequency-dependent interfacial polarization mechanism (related to the interfacial area between polymer and nanoparticles) is responsible for the enhancement of the dielectric constant at the low field. Due to the improvement of chain mobility and stabilization of the polar phase in the polymer/nanoparticle interface regions, the high field dielectric response of nanocomposites was also enhanced in the certain particle loading. Based on the high-field polarization saturation phenomenon, the dimension of interface regions in the nanocomposites was estimated as 20–40 nm. [ABSTRACT FROM AUTHOR]

Fe-doped 0.955Pb(Zn[sub 1/3]Nb[sub 2/3])O[sub 3]-0.045PbTiO[sub 3] (PZNT4.5) single crystals were grown using a high temperature flux technique and the dielectric, piezoelectric, electromechanical, electrostrictive, and electro-optic properties were characterized. The room temperature dielectric permittivity along the <001> direction after poling was about ∼6000 (5000-7000), increased compared to that of pure PZNT4.5 crystals ∼3000-5000. The Curie temperature (T[sub C]) and the rhombohedral to tetragonal phase transition temperature (T[sub r-t]) of doped crystals were about 143 and 92 °C, respectively, more than 20 °C lower than that of the pure crystals. The remnant polarization (P[sub r]) and coercive field (E[sub c]) of <001> oriented doped crystals measured at 1 Hz and 20 kV/cm field were ∼27.3 μC/cm[sup 2] and 4.7 kV/cm, respectively, the latter significantly greater than the E[sub c] of the pure crystals ∼3 kV/cm. Piezoelectric coefficients (d[sub 33]) of <001> oriented doped PZNT4.5 crystals were ∼2500-3000 pC/N, being much higher than that of the pure (1400–2000 pC/N). The electric field induced strain was up to 0.5% with minimal hysteresis at low electric field (E∼15 kV/cm). The longitudinal electromechanical coupling factor k[sub 33] was 92%–93%. The shear mode and lateral mode properties were also studied with piezoelectric coefficient d[sub 15] of ∼3500 pC/N, d[sub 31] of ∼-1800 pC/N, and electromechanical coupling of k[sub 15]∼93%, k[sub 31]∼87%, respectively. The electrostrictive coefficients of Fe-doped PZNT4.5 crystals, Q[sub 11]∼0.099 m[sup 4]/C[sup 2], Q[sub 12]∼-0.048 m[sup 4]/C[sup 2], Q[sub 44]∼0.012 m[sup 4]/C[sup 2], and Q[sub h]∼0.0033 m[sup 4]/C[sup 2] were calculated and compared to those of PZNT4.5 crystals. The apparent electro-optic coefficients of doped crystals were measured to be r[sub 33][sup *]∼... [ABSTRACT FROM AUTHOR]

Poly(vinylidenefluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) terpolymer/Zr[O.sub.2] nanocomposites are used as a model system for examining the polymer/nanoparticle interfaces of the nanocomposites and their effect on dielectric properties of the nanocomposites. The high-field polarization saturation phenomenon has helped in estimating the dimension of interface regions in the nanocomposites.

Based on spin-polarized density functional theory, the characteristics of p-type doping are investigated in the N-doped α-Fe2O3-xSx alloys by means of first-principles methods. Numerical results show that when N substitutes O atom in pure α-Fe2O3, N impurity level is a deeper acceptor state. However, the unoccupied level is much shallower when N doped in the α-Fe2O3-xSx alloys, which indicates N impurity can provide good and effective p-type carriers. These predicted numerical results are interesting and useful to understand the α-Fe2O3-xSx alloys as a new low-cost solar cell material. [ABSTRACT FROM AUTHOR]

Fe-doped 0.955Pb(Zn(sub 1/3)Nb(sub 2/3))O(sub 3)-0.045PbTiO(sub 3) (PZNT4.5) single crystals were grown using a high temperature flux technique and the dielectric, piezoelectric, electromechanical, electrostrictive, and electro-optic properties are characterized. The enhanced piezoelectric activities, coercive field and E-O properties make the Fe-doped PZNT crystals promising materials for the electrical and E-O applications.

The bonding reflector process was used to fabricate a SiGe/Si multiple-quantum-well resonant-cavity-enhanced (RCE) photodetector for 1.3 mue m operations. A full width at half maximum (FWHM) of 6 nm and a quantum efficiency of 4.2 percent at 1314 nm were obtained.

Electronic structure and magnetic properties for MnRhP have been studied from a first-principles density functional calculation. The calculated lattice constants, a=6.228 Å and c=3.571Å, are in good agreement with the experimental values of a=6.223 Å and c=3.585Å. The calculated moment of Mn is 3.1 μB/atom, resulting in a total moment of 3.0 μB/atom due to small moments induced at Rh and P sites. The magnetic moment of Mn decreases with unit cell size. The exchange interactions are dominated by positive Mn-Mn exchange coupling (JMn-Mn), implying a stable ferromagnetic ordering in Mn sublattice. In particular, JMn-Mn shows a maximum value (1.5 mRy) at the the optimized unit cell size. The structural distortion or unit cell size change will affect JMn-Mn, which is intimately related to the magneto-elastic and magneto-caloric effect. [ABSTRACT FROM AUTHOR]

The preferential site substitution of Fe by Ga and its effect on magnetic moments have been studied in Nd2Fe14B by a first-principles density functional calculation. The calculated substitution energies of Ga are positive values and unfavorable for the Ga substitution at the sites of 8j2, 16k1, and 4e, while those are negative values and favorable for the Ga substitution at the sites of 4c, 8j1, and 16k2, in good agreement with the experimental results. The Ga atom shows a small induced negative moment with a size of about 0.2 μB. The magnetic moments of Fe with the nearest neighbor of Ga reduce by about 0.1-0.2 μB while the moments of Nd with the Ga nearest neighbors are enhanced slightly. These magnetic moment changes originate from the hybrid of the Ga 4p- with the Fe 3d- or the Nd 5d-electron states. [ABSTRACT FROM AUTHOR]