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Water-based terahertz (THz) coherent detection scheme has been recently proposed, which overcomes the bandwidth limitation or high probe laser power demand in solid-/gas-based schemes. Here, we report a highly efficient THz coherent detection method using ethanol with superior performances under the mechanism of four-wave mixing. We systematically investigate the energy ratios and relative polarizations between the THz-induced second harmonic and control second harmonic (CSH) beams and reveal that ethanol always exhibits significantly higher detection sensitivity than water. The coherent, incoherent, or hybrid detection mode can be flexibly switched by changing the CSH beam polarization. The enhanced sensitivity derives from the much larger third-order nonlinear coefficient and lower ionization potential of ethanol. In addition, for the ethanol–water mixtures with various concentrations, the THz coherent detection signals can always be decomposed into the linear superposition of those from pure ethanol and neat water at the sub-picosecond timescale, indicating the synergistic contribution of ethanol and water molecules in the mixture during the detection process. This work provides a valid method to significantly improve the sensitivity of the liquid-based coherent detection scheme and a research perspective for exploring the solute–solvent molecular interactions.

Magnetoelectric (ME) sensors are an important tool to detect weak magnetic fields in the industry; however, to date, there are no high-quality ME sensors available for high-temperature environments such as engines, deep underground, and outer space. Here, a 0.364BiScO3–0.636PbTiO3 piezoelectric ceramic and Terfenol-D alloy with a Curie temperature of 450 and 380 °C, respectively, were bonded together by an inorganic glue to achieve a high-temperature ME sensor. The ceramic shows a piezoelectric d33 coefficient of 780 pC/N at 420 °C, and the inorganic glue has a high maximum stress of 9.12 MPa even at 300 °C. As a result, the sensor exhibits the maximum ME coefficient αE of 2.008, ∼1.455, and ∼0.906 V cm−1 Oe−1 at 20, 200, and 350 °C, respectively. Most importantly, the magnetic field detecting precision is as small as 42 nT at 20–350 °C. The ME sensor provides an effective solution for the detection of weak magnetic fields in harsh environments.

The domain reversal dynamics of rhombohedral and tetragonal PIN–PMN–PT ferroelectric single crystals has been investigated by analyzing the variation of hysteresis loops under various electric fields and frequencies. As the electric field amplitude E0 continuously increases, the hysteresis area ⟨A⟩ clearly reflects three stages of polarization reversal. The complete scaling relations of domain reversal dynamics were determined. For rhombohedral PIN–47PMN–29PT crystals, the dynamic hysteresis area follows the law of ⟨A⟩ ∝ f −0.38816E05.21244 in the first E0-stage and ⟨A⟩ ∝ f 0.03553E00.37126 in the third E0-stage. For tetragonal PIN–37PMN–39PT crystals, the dynamic hysteresis area follows the law of ⟨A⟩ ∝ f −0.09054E02.74854 in the first E0-stage and ⟨A⟩ ∝ f −0.15504E02.06936 in the third E0-stage. The negative α indicates that with the alternating velocity of the increasing periodic electric field, more and more domain reversals fail to follow with the alternating electric field. However, rhombohedral PIN–47PMN–29PT crystals possess a positive α in the third E0-stage, indicating that 71° and 109° domains can keep pace with varying E0 more easily. The positive β indicates that when the electric field frequency is fixed, more and more domains begin to reverse with the intensity of the increasing electric field. In addition, the function of ⟨A⟩ ∝ f αE0β cannot be applied to the second E0-stage, where the non-180° domain rotation starts occurring but 180° domain rotation has not finished yet.

The piezoelectric properties of the PZT-5H ceramics under various polarization conditions are compared and analyzed. It is worth noting that compared to direct current polarization, the piezoelectric coefficient (d33), free dielectric constant ( e 33 T/ e 0), and electromechanical coupling coefficient (kt) of the PZT-5H ceramics under alternating current polarization (ACP) have increased by 10.7%, 15.9%, and 15.4%, respectively. According to the analysis of the domain distribution patterns in the [001] surface of the PZT-5H ceramics under the two polarization conditions measured using a piezoresponse force microscope, the ACP makes the piezoelectric material have a high density of the domain wall, which greatly enhances its piezoelectric performance. This work provides an effective means to improve the piezoelectric properties of PZT-5H ceramics and will be of great significance to piezoelectric applications using this type of piezoelectric ceramic.

In this Letter, we report on the evolution of electronic properties governed by epitaxial misfit strain in cubic In2O3 epilayers grown on sapphire. At elevated growth temperature, the competition between the film/substrate lattice mismatch and the thermal expansion mismatch alters the macroscopic biaxial strain from compressive to tensile. Simultaneously, the electron concentration is tuned from degeneration to non-degeneration density below the Mott criterion. The observed surface electron accumulation and metal-insulator transition result from the oxygen deficiency formed at low growth temperature, while high-temperature epitaxy is favorable to achieve remarkably enhanced mobility. The effective strain-property coupling suggests that the improved oxygen stoichiometry and the Fermi level movement controlled by the biaxial strains are responsible for the Mott transition. The strain-mediated reduction of the electron effective mass contributes to the enhanced intrinsic mobility in tensile-strained In2O3 epilayers. These results highlight that strain engineering is an effective stimulus to manipulate the transport properties of oxide semiconductors with improved performance and unexpected functionalities.

Magnetic behavior dependences on the central ions for Ln (Ln = Tb, Dy, Er) phthalocyanines have been studied using direct current and alternating current magnetic susceptibility measurements. The direct current magnetic susceptibility results indicate that the product of the molar magnetic susceptibility and temperature is close to the theoretical value for the current Ln phthalocyanines. A further analysis using the Curie–Weiss law demonstrates the existence of an antiferromagnetic interaction between the Ln ions. Alternating current magnetic susceptibility measurement indicates that both Tb and Dy ions exhibit a slow relaxation with the phthalocyanine ligands compared to that of the Er ion. The effective energy barriers estimated in quantity using the Arrhenius law are 740 K and 40 K for Tb and Dy phthalocyanines, respectively. A theoretical fitting for Cole–Cole plots by the generalized Debye model demonstrates that the Orbach relaxation process prevails in Tb phthalocyanines. The present work clearly demonstrates that the selection of lanthanide ions is important to design single molecule magnets with a high performance.

Epitaxial film quality is critical to the success of high-performance α-Ga2O3 vertical power devices. In this work, the origins of threading dislocation generation and annihilation in thick α-Ga2O3 films heteroepitaxially grown on sapphire by the mist-CVD technique have been examined by means of high-resolution X-ray diffraction and transmission electron microscopies. By increasing the nominal thickness, screw dislocations exhibit an independent characteristic with a low density of about 1.8 × 106 cm−2, while edge dislocations propagating along the c-axis are dominant, which decrease down to 2.1 × 109 cm−2 in density for an 8 μm-thick α-Ga2O3 layer and exhibit an inverse dependence on the thickness. In the framework of the glide analytical model, parallel edge dislocations are generated at the interface due to the misfit-induced strain relaxation, while the dislocation glide and coalescence result in the annihilation and fusion behaviors. The optimal thick α-Ga2O3 with low dislocation densities may provide a prospective alternative to fully realize α-Ga2O3 power devices.

The intrinsic, reversible, and irreversible extrinsic dielectric responses of 0.27Pb(In1/2Nb1/2)O3–0.46Pb(Mg1/3Nb2/3)O3–0.27PbTiO3 relaxor single crystals with and without Mn doping have been extracted by using Rayleigh analysis from 0.1 Hz to 1000 Hz, and the influence of acceptor ions has been quantitatively evaluated. The results show that the lattice deformation under an ac electric field is slightly inhibited by Mn2+/Mn3+, while both reversible and irreversible domain wall motions are greatly suppressed to below 20% of the non-Mn doped values. As a result, the mechanical quality factor, which is closely related to domain wall motions, is significantly enhanced. Meanwhile, the large piezoelectricity, which is dominated by intrinsic contribution, is maintained.

We demonstrate improvements to the cooling power of broad bandwidth (10 GHz) microwave attenuators designed for operation at temperatures below 100 mK. By interleaving 9-$\mu$m thick conducting copper heatsinks in between 10-$\mu$m long, 70-nm thick resistive nichrome elements, the electrical heat generated in the nichrome elements is conducted more readily into the heatsinks, effectively decreasing the thermal resistance between the hot electrons and cold phonons. For a 20 dB attenuator mounted at 20 mK, a minimum noise temperature of $T_{n} \sim$ 50 mK was obtained for small dissipated powers ($P_d, Comment: 5 Pages, 3 figures

Junctionless Germanium-on-insulator (GOI) p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) have been realized with an ultra-thin-body (UTB) channel of down to 6 nm. The hole mobility of 166 cm2/V s has been realized at an Ns value of 1013 cm−2 attributable to the reduction of carrier scattering by interface traps under a bulk transport behavior for the devices. The back bias dependence of the hole mobility in junctionless UTB GOI pMOSFETs was examined; it is found that the hole mobility in the devices is dominated by the surface roughness scattering at the MOS interface.

We propose a chip-scale hollow-core waveguide using high-contrast gratings as reflectors for dielectric laser acceleration. We show that confinement of a specified accelerating mode can be achieved by adjusting the thickness of a matching layer between the core and the highly reflective grating. Several examples of the grating-based waveguide and their characteristic parameters such as the group velocity, interaction impedance, and acceleration efficiency are presented. The planar structure of the waveguide makes fabrication and integration simple, which is required by an on-chip dielectric laser accelerator for high-energy, material, and medical applications.

We report excitation-wavelength-dependent terahertz wave modulation via a preformed air plasma created by a synchronized 800-nm laser pulse traveling orthogonal to the pump pulses. With a preformed plasma, both the modulation depth of the terahertz energy and the change in terahertz wave polarization increase with the increasing excitation-laser wavelength. The results are well explained by the photocurrent model with a wavelength-dependent ionization rate. We also experimentally detect the refractive index of the two-color field changed by the preformed air plasma. These results improve our understanding of the theoretical mechanism and expand the practical applications of terahertz wave generation and modulation.

We show that the accelerating gradient of a dual-grating structure for dielectric laser acceleration of subrelativistic electrons can be enhanced by resonating with the zeroth diffraction order inside the channel. We analyze diffraction of light at a subwavelength grating (SWG) to illustrate the principle of the resonant enhancement. We present examples of dual-grating resonators for 50 keV electrons with different channel widths. The dependence of reflectivity and phase on the SWG dimensions provides flexibility in controlling the enhancement factor and filling time, thus enabling high-gradient acceleration driven by ultrashort low-power laser pulses.

Extrinsic contributions play an important role in the functionalities of ferroelectric materials, while domain structure evolution is crucial for understanding the extrinsic dielectric and piezoelectric responses. In this work, domain configuration changes with an electric field applied along [001]C in the tetragonal (K, Na, Li)(Nb, Sb, Ta)O3 single crystal were studied by means of polarizing light microscopy. Results show that parts of the spontaneous polarizations in the (001)C plane are switched to [001]C direction, while others still stay in the (001)C plane due to high induced internal stresses. Single domain state cannot be achieved even under a high electric field. After being poled along [001]C, the volume fraction of domains with polarzations in the (001)C plane is still about 25.2%. The extrinsic contributions to the dielectric constant are 15.7% and 27.2% under the E field of 1 kV/cm and under 2 kV/cm, respectively, estimated by the Rayleigh analysis.

Due to the confusion in choosing coordinate systems, there occurred some misrepresentations/calculations of effective material properties of 0.67Pb(Mg1∕3Nb2∕3)O3–0.33PbTiO3 single crystals based on its single-domain data. This letter is to clarify these confusions by providing proper data set for each of the currently used coordinate systems.

Weak anti-localization of the two-dimensional electron gas (2DEG) in a modulation-doped Al0.22Ga0.78N∕GaN single heterostructure has been investigated through magnetoresistance measurements at low temperatures. The elastic scattering time τe, dephasing time τϕ and spin-orbit scattering time τso at various temperatures are obtained. When the second subband in the triangular quantum well at the heterointerface is occupied by the 2DEG, the weak anti-localization is observed clearly, which is thought to be due to the strong spin-orbit effect induced by the intersubband scattering. The spin-orbit effect and the intersubband scattering become stronger with increasing temperature.

Strong space charge response is observed in SiC ceramic capacitors at low frequencies up to 0.1MHz. It leads to a dielectric constant of 2 910 000 at 100Hz. The critical temperature is observed near 773K. The losses decrease with increasing temperature. Strong frequency dependence of the dielectric properties is also detected. The SiC ceramic capacitor might be suitable as high-temperature by-pass capacitor in low voltage circuits.

A graphene/LiNbO3 hybrid device is used to investigate the acoustic induced charge transport in chemical doped graphene. The chemical doping of graphene via its physisorption of gas molecules affects the surface acoustic wave (SAW) charge carrier transport in a manner different from electric field drift. That transport induces doping dependent macroscopic acoustoelectric current. The chemical doping can manipulate majority carriers and induces unique acoustoelectric features. The observation is explained by a classical relaxation model. Eventually the device based on acoustoelectric current is proved to outperform the common chemiresistor for chemicals. Our finding provides insight into acoustic charge carrier transport during chemical doping. The doping affects interaction of carriers with SAW phonon and facilitates the understanding of nanoscale acoustoelectric effect. The exploration inspires potential acoustoelectric application for chemical detection involving emerging 2D nanomaterials.

The ultra-thin body and ultra-thin buried-oxide (UTBB) Germanium-on-Insulator (GeOI) substrates have been fabricated by direct wafer bonding and polishing techniques. The Ge and BOX layer thicknesses are as thin as 9 and 13 nm, respectively. The UTBB GeOI substrates exhibit superior crystal quality (similar to the bulk single crystalline Ge) and sufficiently reduced surface roughness. As a result, the Hall hole mobility of UTBB GeOI reaches 1330 cm2/V s with a carrier concentration of 2 × 1016 cm−3. The inversion mode UTBB GeOI nMOSFETs have also been demonstrated with suppressed mobility degradation during Ge layer thinning, indicating the feasibility of this GeOI substrate formation technique in future CMOS technologies.

Optical temperature sensing based on the variation of the fluorescence intensity ratio of rare-earth materials has become appealing due to the multiple superiorities over the electrical temperature sensing. However, confined by the largest energy separation of two thermally linked levels of rare-earth ions, the highest sensitivity of such temperature sensing is essentially smaller than 2878/T2, as reported previously from diverse systems. In this work, we demonstrate that ultrahigh-sensitive temperature sensing can be achieved from Pr3+-doped (K0.5Na0.5)NbO3 based on the intensity ratio of the 1D2-3H4 emission to the 3P0-3H4 emission. The ratio can be increased as high as 18-fold when temperature rises from room temperature to 456 K, nicely fitting a thermally linked-levels-like equation and showing an ultrahigh sensitivity of 7997/T2. The striking change of the ratio is attributed to the interaction between the two emission levels and the intervalence charge transfer state. This work may have provided a ...

We have demonstrated a low temperature formation (300 °C) of higher-k HfO2 using atomic layer deposition (ALD) on an in-situ thermal oxidation GeOx interfacial layer. It is found that the cubic phase is dominant in the HfO2 film with an epitaxial-like growth behavior. The maximum permittivity of 42 is obtained for an ALD HfO2 film on a 1-nm-thick GeOx form by the in-situ thermal oxidation. It is suggested from physical analyses that the crystallization of cubic phase HfO2 can be induced by the formation of six-fold crystalline GeOx structures in the underlying GeOx interfacial layer.

The orientation dependence of piezoelectric properties has been calculated for 0.67Pb(Mn1/3Nb2/3)O3–0.33PbTiO3 (PMN–33%PT) single-domain crystals based on the measured full matrix properties. It is found that the maximum d33*=2411 pC/N and k33*=0.94 occur, respectively, in directions 63.0° and 70.8° from the spontaneous polarization direction. In [001] of the cubic coordinate, the rotated properties are d33*=2316 pC/N and k33*=0.93, respectively, comparable to the measured multidomain properties. The results revealed the origin of the superior electromechanical properties in [001] poled PMN–33%PT multidomain crystals as from the large d15 of the single-domain property.

We report a complete set of material properties of single-domain, relaxor-based 0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 [PMN–33%PT] single crystals. Because the single-domain state is unstable in natural conditions, a bias electric field of 0.2 MV/m was applied along the dipole direction of the rhombohedral phase during the measurements. It was found that the electromechanical coupling coefficient k33 and the piezoelectric constant d33 for single-domain PMN–33%PT are 69% and 190 pC/N, respectively. Both of them are much smaller than those of multidomain PMN–33%PT poled along [001] direction. However, the shear piezoelectric constant d15 of single-domain PMN–33%PT reaches 4100 pC/N, which is much higher than that of multidomain PMN–33%PT.

The piezoelectric properties of [001](c) poled 0.94Pb(Zn(13)Nb(23))O(3)-0.06PbTiO(3) single crystals were greatly enhanced by controlling their domain configurations. Contrary to the interpretation of charged domain walls being the main contributor to the piezoelectric enhancement, we found that smaller domain size and more neutral domain walls were the main contributors for the piezoelectric enhancement of these multidomain crystals. The properties of 109 degrees neutral domain walls in 0.94Pb(Zn(13)Nb(23))O(3)-0.06PbTiO(3) single crystals were extracted by using a piezoelectric domain wall model.

Surface acoustic wave (SAW) propagation properties in relaxor-based 0.67Pb(Mg(13)Nb(23))O(3)-0.33PbTiO(3) (PMN-33%PT) ferroelectric single crystals poled along [111](c) has been analyzed theoretically. We found that the X-cut PMN-33%PT has lower phase velocity and higher electromechanical coupling coefficient compared to traditional piezoelectric materials. The power flow angle (PFA) can be zero in specific directions, which could drastically improve the performance of SAW devices. Our theoretical results indicate that the direction about 5 degrees canted from [111](c) is the optimum direction for the X-cut [111](c) poled crystals in SAW device applications. Characteristic curves were also obtained for the phase velocity, electromechanical coupling coefficient, and PFA in Z-cut single-domain PMN-33%PT single crystals.

The influence of cooling and heating rates on the spinodal temperature of lysozyme liquid–liquid phase separation was assessed under microgravity and normal gravity. During both heating and cooling, the mean spinodal temperature was independent of gravity conditions and the rate of temperature change. However, during the cooling process, the spinodal temperature was always lower under microgravity than under normal gravity, whereas the opposite effect was observed under heating. We attribute this phenomenon to the hydrodynamic effect. Under normal gravity, mass transfer occurs by universal convection, but under microgravity it can occur only by diffusion. Because of the relatively small diffusivity of lysozyme molecules, the size evolution of the dense liquid domain was slower under microgravity than under normal gravity.

Extrinsic contributions play an important role in the functionalities of ferroelectric materials, while domain structure evolution is crucial for understanding the extrinsic dielectric and piezoelectric responses. In this work, domain configuration changes with an electric field applied along [001]C in the tetragonal (K, Na, Li)(Nb, Sb, Ta)O3 single crystal were studied by means of polarizing light microscopy. Results show that parts of the spontaneous polarizations in the (001)C plane are switched to [001]C direction, while others still stay in the (001)C plane due to high induced internal stresses. Single domain state cannot be achieved even under a high electric field. After being poled along [001]C, the volume fraction of domains with polarzations in the (001)C plane is still about 25.2%. The extrinsic contributions to the dielectric constant are 15.7% and 27.2% under the E field of 1 kV/cm and under 2 kV/cm, respectively, estimated by the Rayleigh analysis.

In this study of resistance random access memory in a resistive switching film, the breakdown degree was controlled by varying forming current compliance. A SiOx layer was introduced into the ZnO layer of the structure to induce both typical bipolar resistive switching (RS) and complementary resistive switching (CRS). In addition, the SiOx layer-generated vacuum spaces in typical bipolar RS can be verified by electrical characteristics. Changing forming current compliance strikingly modifies the oxygen storage capacity of the inserted SiOx layer. CRS can be achieved, therefore, by tuning the oxygen ion storage behavior made possible by the SiOx layer.

Morphotropic phase boundary (MPB), separating two ferroic phases of different crystal symmetries, has been studied extensively for its extraordinary enhancement of piezoelectricity in ferroelectrics. Based on the same mechanism, we have designed a magnetic MPB in the pseudobinary ferromagnetic system of Tb1−xGdxFe2 and the corresponding crystal structure, magnetic properties, and magnetostriction are explored. With the synchrotron x-ray diffractometry, the structure symmetry of TbFe2-rich compositions is detected to be rhombohedral (R) and that of GdFe2-rich compositions is tetragonal (T) below Tc. With the change of concentration, the value of magnetostriction of the samples changes monotonously, while the MPB composition Tb0.1Gd0.9Fe2, which corresponds to the coexistence of R and T phases, exhibits the maximum magnetization among all available compositions and superposition of magnetostriction behaviour of R and T phases. Our result of MPB phenomena in ferromagnets may provide an effective route to design functional magnetic materials with exotic properties.

KTa1−xNbxO3 single crystals are typically regarded as normal ferroelectrics. Such crystals are thought to undergo a paraelectric-ferroelectric phase transition from the cubic to the tetragonal phase where generally a single hysteresis loop is expected. Nevertheless, a double-loop hysteresis is clearly observed in the tetragonal phase of KTa0.58Nb0.42O3. Our investigations reveal further that the double loop exhibits good ergodicity during changes in temperature under various applied electric fields. The origin of this unusual double-loop hysteresis in tetragonal KTa0.58Nb0.42O3 is revealed with the recoverable reorientation of the asymmetric polar domains.

Precipitation behaviors of Cu and Fe on Frank‐type partial dislocations bounding bulk stacking faults in Czochralski‐grown silicon are investigated by means of the electron beam‐induced‐current (EBIC) technique and transmission electron microscopy (TEM). Frank partials in a Cu‐contaminated specimen do not exhibit an EBIC contrast at room temperature when the specimen is cooled slowly; however, in the Fe‐contaminated specimen, they exhibit EBIC contrast at room temperature due to their Fe contamination. The TEM micrograph shows that Cu develops precipitate colonies in the region away from stacking faults and does not precipitate on Frank partials in the specimen. The results indicate that Fe impurity decorates Frank partials more easily than Cu impurity in Si.

We propose and demonstrate gold nanoparticle decorated graphene as an ideal system for studying carrier inhomogeneity induced magnetoresistance. Large linear magnetoresistance has been realized in the system and the magnitude can be tuned by a gate. By detailed study, we provide an empirical expression, which reveals the dependence of the magnetoresistance on density fluctuations and mobility. The induced magnetoresistance is temperature independent and can be strongly enhanced by the high mobility of graphene, hence offers potential for magnetic sensor applications.

A low-temperature ultra-violet (UV) light enhanced supercritical CO2 (SCCO2) fluid treatment is employed to improve the performance of In-Ga-Zn-O (IGZO) thin film transistor (TFT) device. In this study, amorphous IGZO film deposited by sputtering is investigated in SCCO2 ambient under different illumination conditions. After SCCO2 treatment with UV exposure, the mobility and subthreshold swing of the TFT can be significantly improved. A model is proposed to explain the mechanism, and the improvement is due to the reduction of dangling bonds at the grain boundary. With the help of UV, dangling bonds can be effectively passivated by OH chemical groups.

In this Letter, the characteristics of set process of hafnium oxide based resistance random access memory are investigated by different set processes with increasing compliance current. Through current fitting, carrier conduction mechanism of low resistance state changes from hopping to surface scattering and finally to ohmic conduction with the increase of setting compliance current. Experimental data of current-voltage measurement under successive increasing temperature confirms the conduction mechanism transition. A model of filament growth is eventually proposed in a way by merging discrete metal precipitates and electrical field simulation by comsol Multiphysics further clarifies the properties of filament growth process.

Lead-free piezoelectric single crystal 0.95(Na0.5Bi0.5)TiO3 (NBT)-0.05BaTiO3 was grown by top-seeded solution growth method, which has rhombohedral symmetry with composition near morphotropic phase boundary. Full set of dielectric, piezoelectric, and elastic constants for [001]c poled domain-engineered single crystal was determined. Excellent electromechanical properties and low dielectric loss (d33 = 360 pC/N, d31 = −113 pC/N, d15 = 162 pC/N, k33 = 0.720, kt = 0.540, and tan δ = 1.1%) make it a good candidate to replace lead-based piezoelectric materials. The depolarization temperature (Td = 135 °C) is the highest among all NBT-based materials and its electromechanical coupling properties are very stable below Td. Extrinsic contributions to piezoelectric properties were investigated by Rayleigh analysis.

Molecular-like Ag clusters sized at 1–4 nm have been stabilized in Pb/Cd-free oxyfluoride glasses, showing broadband excitation/emission characteristics and unique wavelength-dependent luminescent performance with a maximal quantum yield of 26.9%. It was experimentally demonstrated that an energy transfer route of Ag clusters → Tb3+ → Yb3+ occurs in Ag+/Tb3+/Yb3+ tri-doped sample, wherein Ag clusters act as sensitizers for near-infrared down-conversion spectral modification. Hopefully, the proposed strategy that noble metal clusters being applied for harvesting solar radiation may potentially solve the sticky problems of the narrow excitation bandwidth and the low excitation efficiency in rare earth ions doped down-conversion materials.

In this study, the electrical conduction mechanism of Zn:SiOx resistance random access memory (RRAM) treated with supercritical CO2 fluid (SCCO2) process was investigated by low temperature measurement. The current of low resistance state for current-voltage curves in SCCO2-treated and untreated Zn:SiOx RRAM were measured and compared under a low temperature range from 100 K to 298 K. The electrical conduction mechanisms of hopping conduction and metal-like behaviors in SCCO2-treated and untreated Zn:SiOx RRAM were discussed, respectively. Finally, the electrical conduction mechanism was analyzed and verified by the chemical composition and bonding intensity of XPS analyses.

We have derived a general formula for sensitivity optimization of gravimetric sensors and use it to design a high sensitivity gravimetric sensor using unidirectional carbon fiber epoxy composite (CFEC) guiding layer on (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) single crystal substrate. The normalized maximum sensitivity (|Smf|λ)max exhibits an increasing tendency with the decrease of (h/λ)opt. For the CFEC/[011]c poled PMN-0.29PT sensor configuration with λ = 24 μm, the maximum sensitivity |Smf|max can reach as high as 1230 cm2/g, which is about 3 times that of a traditional SiO2/ST quartz configuration gravimetric sensor.

A bilayer resistive switching memory device with an inserted porous silicon oxide layer is investigated in this letter. Compared with single Zr:SiOx layer structure, Zr:SiOx/porous SiOx structure outperforms from various aspects, including low operating voltages, tighter distributions of set voltage, higher stability of both low resistance state and high resistance state, and satisfactory endurance characteristics. Electric field simulation by comsolTM Multiphysics is applied, which corroborates that intensive electric field around the pore in porous SiOx layer guides the conduction of electrons. The constraint of conduction path leads to better stabilization and prominent performance of bilayer resistive switching devices.

In this study, the hopping conduction distance variation of Zn:SiO2 resistance random access memory (RRAM) devices with different operating compliance currents was discussed and verified. To investigate and determine the hopping conduction distance dependent activation energy characteristics, the Arrhenius plot of low resistance state of Zn:SiO2 RRAM devices was applied, from which we proposed carrier conduction model. With the increase of current compliance, more metal ions would accumulate to form precipitates with larger diameter, which in turn resulted in the shortening of hopping distance. Because of shorter hopping distance, activation energy for carrier hopping would decrease.

We have systematically measured the room-temperature thermal conductivity of epitaxial layers of InxGa1−xN alloys with 15 different Indium compositions ranging from 0.08 to 0.98 by time-domain thermoreflectance method. The data are compared to the estimates of the strength of phonon scattering by cation disorder. The thermal conductivity is in good agreement with the theoretical modeling results based on the mass difference for In-rich (x > 0.9) and Ga-rich (x

The ultrathin GeOx/Ge interfaces formed on Ge (100) and (111) surfaces by applying plasma post oxidation to thin Al2O3/Ge structures are characterized in detail using X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy. It is found that the XPS signals assigned to Ge 1+ and the 2+ states in the GeOx layers by post plasma oxidation have oscillating behaviors on Ge (100) surfaces in a period of ∼0.3 nm with an increase in the GeOx thickness. Additionally, the oscillations of the signals assigned to Ge 1+ and 2+ states show opposite phase to each other. The similar oscillation behaviors are also confirmed on Ge (111) surfaces for Ge 1+ and 3+ states in a period of ∼0.5 nm. These phenomena can be strongly regarded as an evidence of the atomic layer-by-layer oxidation of GeOx/Ge interfaces on Ge (100) and (111) surfaces.

We present few-layer graphene synthesis by negative carbon cluster ion implantation with C1, C2, and C4 at energies below 20 keV. The small C-clusters were produced by a source of negative ion by cesium sputtering with medium beam current. We show that the nonlinear effect in cluster-induced damage is favorable for graphene precipitation compared with monomer carbon ions. The nonlinear damage effect in cluster ion implantation shows positive impact on disorder reduction, film uniformity, and the surface smoothness in graphene synthesis.

High-quality germanium dioxide (GeO2) as a gate oxide is in high demand for use in future high mobility Ge-channel field-effect transistors. GeO2 thin films were directly formed by using a damage-free and low-temperature process of neutral beam oxidation (NBO) after treatment with hydrogen (H) radicals. GeO2 thin films (equivalent oxide thickness (EOT) = 1.7 nm) with a high-quality interface and an extremely low interface state density (