Si Structures Research Articles

Investigation of the Temperature Effect on Electrical Characteristics of Al/SiO2/n++-Si RRAM Devices.

In this work, we investigate the effect of temperature on the electrical characteristics of Al/SiO2/n++-Si RRAM devices. We study the electroforming process and show that forming voltage and time-to-breakdown are well described by Weibull distribution. Experimental current–voltage characteristics of Al-SiO2-(n++Si) structures are presented and discussed at different temperatures. We show that some intermediate resistance states can be observed at higher temperatures. In our analysis, we identify Space Charge Limited Conduction (SCLC) as the dominating transport mechanism regardless of the operating temperature.

Compact SPICE Model of Memristor with Barrier Modulated Considering Short- and Long-Term Memory Characteristics by IGZO Oxygen Content.

This paper introduces a compact SPICE model of a two-terminal memory with a Pd/Ti/IGZO/p+-Si structure. In this paper, short- and long-term components are systematically separated and applied in each model. Such separations are conducted by the applied bias and oxygen flow rate (OFR) during indium gallium zinc oxide (IGZO) deposition. The short- and long-term components in the potentiation and depression curves are modeled by considering the process (OFR of IGZO) and bias conditions. The compact SPICE model with the physical mechanism of SiO2 modulation is introduced, which can be useful for optimizing the specification of memristor devices.

Structure and properties of Si and N co-doping on DLC film corrosion resistance

Three species of diamond-like carbon (DLC) film were systematically examined in NaCl solution for their anticorrosion properties. Si&N&H-DLC has better electrochemical characteristics and salt spray corrosion testing results than the substrate and two species DLC films in NaCl solution. Due to the successive growth of Si, N, and H-DLC, there is a well-bonded Si–N interface and the formation of Si oxides. The Si&N&H-DLC film exhibits extremely high charge transfer resistance, exceeding 106 Ω/cm2. A salt spray test shows that the Si&N&H-DLC film presents a lower rate in NaCl solution in comparison to the substrate and the other two species of DLC films. As a result, the Si&N&H-DLC film significantly improved the corrosion performance of the substrate.

Memristive Switching and Density-Functional Theory Calculations in Double Nitride Insulating Layers.

In this paper, we demonstrate a device using a Ni/SiN/BN/p+-Si structure with improved performance in terms of a good ON/OFF ratio, excellent stability, and low power consumption when compared with single-layer Ni/SiN/p+-Si and Ni/BN/p+-Si devices. Its switching mechanism can be explained by trapping and de-trapping via nitride-related vacancies. We also reveal how higher nonlinearity and rectification ratio in a bilayer device is beneficial for enlarging the read margin in a cross-point array structure. In addition, we conduct a theoretical investigation for the interface charge accumulation/depletion in the SiN/BN layers that are responsible for defect creation at the interface and how this accounts for the improved switching characteristics.

Analysis of recombination centers near an interface of a metal–SiO2–Si structure by double carrier pulse deep-level transient spectroscopy

This paper proposes a new double carrier pulse deep-level transient spectroscopy (DC-DLTS) method that is applicable for evaluating metal–insulator–semiconductor (MIS) structures and the recombination centers in carrier-selective contact solar cells. Specifically, this study evaluated recombination characteristics of defects induced in bulk Si near SiO2/Si interfaces by reactive plasma deposition (RPD). In this method, a pulse voltage was first applied to inject majority carriers. Subsequently, a second pulse voltage was applied, which allowed minority carriers to be injected into the MIS structure. With these two types of carrier injections, carriers were recombined in recombination-active defects, and the DC-DLTS spectrum changed. During the injection of minority carriers, some majority carriers were thermally emitted from the defects, resulting in a decrease in the signal intensity. The recombination activity was analyzed by considering the effect of thermal emission on the change in signal intensity. The number of induced defect types and defect properties were estimated using Bayesian optimization. According to the results, three types of electron traps were generated using the RPD process. Based on the DC-DLTS results, defects with energy level 0.57 eV below the conduction band and capture cross section of ∼10−15 cm2 act as recombination centers.

Microalloying-modulated strength-ductility trade-offs in as-cast Al–Mg–Si–Cu alloys

This work presents detailed and quantitative strengthening effects from various kinds of secondary phases in as-cast Al–Mg–Si–Cu alloys for the first time, through changing Ge and Sb content. Three typical kinds of strength-ductility trade-off relations are elaborated by deformation, embrittling and strengthening mechanisms, as reflected by solidification experiments, multi-mechanistic models and first-principles calculations. Microalloying-modulated strength-ductility trade-offs are strongly associated with their special microstructures, where the size and volume fraction of coarse primary phases increase and fine precipitates are modified. As compared to the secondary phases contributing up to 81.9% of the total strength, strengthening effects from solid-solution atoms (6.5–8.7%), grain boundaries (1.8–2.5%) and coarse primary phases are negligible. Therefore, the increased strength of modified alloys is modulated by modifying the fine precipitates, including Mg2Si (β) plates, Al4Cu2Mg8Si7 (Q) needles, Al2Cu (θ) dispersoids, (Ge, Si) rods/particles and nano-sized Si particles. On the other hand, the decreased ductility of modified alloys is determined by the secondary phases, especially the coarse primary phases like β, Q, Mg3Sb2, Mg2(Ge, Si) and (Ge, Si) structures, which also implies that the ductility cannot be predicted by the Peierls’ ductility D derived from simulating α-Al solid solutions by first-principles methods.

Thermo-kinetic synergy and micro-alloying effects of multiphase transformations in an as-cast Al-Mg-Si-Cu alloy

This work explores effects of Ge and Sb on the formation of secondary phases, with an emphasis laid on the thermo-kinetics of phase transformations and the mechanisms determining the micro-alloying effects. The results reveal that the dominating microstructures in an Al-Mg-Si-Cu alloy, including Mg2Si, Al4Cu2Mg8Si7 (Q), Si and Al2Cu (θ) phases, are thermal activated. Compared to elemental Si, intermetallic compounds like Mg2Si and Q phases have larger critical nucleation radius and phase-transformation energy barrier, and the larger thermodynamic driving force and kinetic migration energy barrier generally result in the finer microstructures. Micro-alloying affects the phase transformations in two ways: the element Sb not only promotes forming Mg3Sb2 phases but also facilitates the formation of elemental Si, Q needles and θ dispersoids through the mismatch effect; whereas the element Ge facilitates the formation of (Ge, Si) structures with different shapes and crystal structures by a substitution behavior following the formation energy criterion.

Modeling of Structure H Carbon Dioxide Clathrate Hydrates: Guest-Lattice Energies, Crystal Structure, and Pressure Dependencies.

We performed first-principles computations to investigate the complex interplay of molecular interaction energies in determining the lattice structure and stability of CO2@sH clathrate hydrates. Density functional theory computations using periodic boundary conditions were employed to characterize energetics and the key structural properties of the sH clathrate crystal under pressure, such as equilibrium lattice volume and bulk modulus. The performance of exchange–correlation functionals together with recently developed dispersion-corrected schemes was evaluated in describing interactions in both short-range and long-range regions of the potential. Structural relaxations of the fully CO2-filled and empty sH unit cells yield crystal structure and lattice energies, while their compressibility parameters were derived by including the pressure dependencies. The present quantum chemistry computations suggest anisotropy in the compressibility of the sH clathrate hydrates, with the crystal being less compressible along the a-axis direction than along the c-axis one, in distinction from nearly isotropic sI and sII structures. The detailed results presented here give insight into the complex nature of the underlying guest–host interactions, checking earlier assumptions, providing critical tests, and improving estimates. Such entries may eventually lead to better predictions of thermodynamic properties and formation conditions, with a direct impact on emerging hydrate-based technologies.

Temperature dependence of electrical characteristics and interface state densities of Au/n-type Si structures with SnS doped PVC interface

In this study, the electrical properties of Au/(SnS doped PVC)/n–Si structures were investigated in detail using current/voltage (IV) data in wide temperature range (80–340 K by 20 K steps). Some of the basic electrical parameters such as ideality factor (n), saturation current (I 0), and barrier height (Φ bo ) were obtained. When these parameters were extracted using thermionic emission (TE) theory, it was found that the value of n decreases whereas Φ bo increases with increasing temperature. This result can be explained by the barrier height (BH) inhomogeneity. The observed two linear regions in the plots of Φ bo –n, Φ bo –(1/2kT)1 and (n −1–1)–(1/2kT) in temperature regions of 80–160 K and 80–340 K form an evidence to the presence of Double Gaussian distribution (DGD). Using the plot of Φ bo –(1/2kT), the values of mean BH () and standard deviation (σ S) were found as 0.486 eV and 66 mV for first region, and 0.984 eV and 139 mV for second region, respectively. Thus, the effective Richardson constant (A*) was obtained using the interception point of the modified Richardson plot for these regions as 7.013 × 10−6 A.K−2cm−2 and 88.12 A.K−2cm−2, respectively. It is clear that A* value for second region is closer to theoretical value (=112 A.K−2cm−2 for n–Si). Finally, the energy dependent profile of the surface-states (Nss) was extracted using Card-Rhoderick method and Nss was found to range from ∼1012 (at 80 K) to 1013 eV−1 cm−2 (at 340 K).

Electric field enhancement by a hybrid dielectric-metal nanoantenna with a toroidal dipole contribution.

Plasmonic nanocavities enable extreme light-matter interactions by pushing light down to the nanoscale. The numerical simulation is carried out systematically on the slotted Φ-shaped Si disk system with the super-dipole mode based on the analysis of the scattering strength of electric and toroidal dipoles. New blocks are introduced to the zero-field strength region of a slotted Si disk system as a function of the field enhancement factors. The far-field scattering characteristics and near-field electromagnetic field distributions are investigated by a multipole decomposition analysis to elucidate the intrinsic causes of the field enhancement. In the hybrid metal-dielectric nanoantenna, the Φ-shaped Si structure is prepared by superimposing Au nanoantennas for further field enhancement. In addition, the effects of the placement of an electric dipole emitter on the Purcell factor are derived. The geometric volume of the system is increased, and the electric field strength is improved, leading to an electric field increase of ∼30. Coupling between the super-dipole mode of the dielectric nanostructure and plasmonic modes of the metallic nanoantenna produces an enhancement as large as 16 times. Our results reveal a greatly enhanced super-dipole mode by electromagnetic coupling in composite structures, which will play a significant role in enhanced nonlinear photonics, near-field enhancement spectroscopy, and strong photon-exciton coupling.

Large near-infrared lateral photovoltaic effect in an organic egg albumin/Si structure

Previously reported photoelectric devices have mainly been limited to inorganic materials. Even though preparing high-performance photoelectric devices with organic biomaterials is an inevitable trend in commercialization, fabricating organic photoelectric devices based on naturally occurring materials with high sensitivity remains a great challenge due to the high resistivity of and few free electrons in these materials. Herein, high-performance photoelectric devices based on an egg albumin (EA)/Si structure are proposed, and a new, to the best of our knowledge, perspective is provided on photodetection in naturally occurring materials by utilizing the surface state of p-Si to separate light-induced carriers effectively. The free electrons of metal atoms restrain the surface states, leading to a sensitivity of 5 mV/mm for metal/Si devices, while the sensitivity of the EA/Si device in the near-infrared region is greatly promoted to 357 mW/mm, which is intimately related to the lack of effect of EA on the dangling bonds of the surface. The EA/Si device is among the most sensitive organic near-infrared photoelectronic device to date. This work opens up new avenues to overcome the obstacle of the low sensitivity of organic photodetectors, indicating that the EA/Si device has great potential for future applications in flexible photovoltaic devices.

Effect of illumination intensity on the electrical characteristics of Au//SiO2/n-type Si structures with GO and P3C4MT interface layer

Effect of illumination intensity on the electrical characteristics of Au//SiO2/n-type Si structures with GO and P3C4MT interface layer

Dielectric Characterization of Al/PAN/n˗Si/Al Structure as a Function of Frequency and Voltage

In this study, the voltage and frequency dependencies of dielectric properties of Al/Polyacrylonitrile (PAN)/n˗Si/Al metal/polymer/semiconductor (MPS) were analyzed. To determine the dielectric characteristics, capacitance˗voltage (C–V) and conductance˗voltage (G–V) of Al/PAN/n˗Si/Al were measured depending on the frequency and bias voltage ranges in 10 kHz–1 MHz and ±5 V at room temperature. Using the C–V and G–V measurements, dielectric parameters; ε′, ε″, and tan δ, M′and M″, were evaluated depending on voltage and frequency. As the frequency increased, ε′ and ε″ decreased, while peaks related to the relaxation mechanism were observed in M″ and tan δ. The ε′ values at 10 kHz and 1 MHz are 15.2 and 4.58 for 1 V, respectively. Relaxation times were calculated using the peaks in the M″˗f plot and it was seen that the relaxation time decreased as the bias voltage increased. Relaxation mechanism is related to non˗Debye relaxation in PAN/n–Si structure. The existence of relaxation peaks in M″ curves showed that the studied material is an ionic conductor.

Gyrification structure of Si–Al thin film anodes with high-rate performance

Si–Al thin films with the different sputtering power and time were prepared by radio frequency (RF) magnetron sputtering. Si–Al thin film with deposition time of 40 min at sputtering power of 100 W has a better initial discharge specific capacity of 2186 mAhg−1 and initial coulombic efficiency (ICE) of 89.5%. The method of hydrochloric acid (HCl) etching can be used to obtain both higher capacity and cyclic stability in Si–Al thin film anodes. The solid electrolyte interphase (SEI) layer is formed by etching Si–Al thin film with 1 M HCl for 40 min (1M-40min). It shows a robust gyrification structure with plentiful folds, which can provide abundant reaction sites for electrochemical reactions, and exhibit the adaptability to the high current density. The mechanisms involved in the formation and constitution of SEI layer have been discussed in details. The 1M-40min Si–Al thin film anode shows a high initial discharge specific capacity of 2854 mAhg−1 at 0.8 Ag-1, which reaches to 2561 mAhg−1 at 5.0 Ag-1. The specific capacity of this anode is kept above 1459 mAhg−1 at 20 Ag−1 and can recover to 1981 mAhg−1 when the current density is restored to 0.5 Ag−1.

IR TRANSMITTANCE OF Si/SiO2/Si3N4/Si ISLAND STRUCTURES FORMED BY SELECTIVE LASER ANNEALING

Periodic Si/SiO2/Si3N4/Si structures with an insular surface layer were formed by selective laser annealing. The study by infrared Fourier spectrometry showed a decrease in the transmittance of the island structure formed by selective laser annealing compared to the structure without annealing in range 2–25 microns. It is shown that the decrease in the transmittance value may be due to the presence of highly alloyed regions of recrystallized silicon in the surface layer. Analysis of dispersion curves obtained by FDTD modeling showed that plasma-like oscillations were detected in the range of 5–20 THz, which can support in layers of periodic high-alloyed silicon islands in a layer of unalloyed silicon. The results of the study are interpreted considering the assumption of the occurrence of “spoof” surface plasmons in a structure with an insular surface layer.

Improved strong field enhancement and ultranarrow perfect absorption based on anapole mode in slotted Si nanodisk metamaterial

Compared with the plasmon resonance suppressed by ohmic loss, high refractive index dielectric metamaterials have become a new frontier of nanophotonics because of their small loss. In this work, we numerically simulate the structures of Si and slotted Si nanodisk with the SiO2 substrate, and slotted Si nanodisk with the Ag substrate. The slotted Si nanodisk excited with anapole mode reveals strong near field enhancement about 70 times in slotted gap regions. When the slotted Si nanodisk deposited on Ag substrate separated by SiO2 layer, the designed structure shows the ultranarrow perfect absorption with the line width of 1.38 nm and the quality factor of 602, and the corresponding electric field enhancement in the Si nanodisk increases to 125. Our work provides a new idea for electric field enhancement and ultranarrow perfect absorption based on manipulation of anapole mode in dielectric metamaterials, and provides potential applications in optical sensors, nonlinear optics and surface enhanced Raman scattering.

Investigation and Characterization of in-Situ Polymer Brush SEI Core Shell Layer Effects on Si Anode Material and Its Battery Performance

Silicon is a promising material for lithium-ion batteries due to its super high capacity.1 However, the volume expansion and the pulverization of Si limit its perforamce.2 This study investigates the effect of a polymer brush core-shell structure of Si as an anode material. The polymer brush is designed through Si-C covalent bond of vinyl monomers by thermal hydrosilylation reaction. According to the results, the PBCS structure provides three significant functions on Si particles because of the intramolecular effect of hydrogen bonding with PBCS and binder delivers a good dispersion in the slurry, a mechanical protection during cycling, and excellent ionic conductivity for high-rate tests. Compared with the unmodified electrode (SiNP), the modified electrodes (SiNP-M1 and SiNP-M2) incorporating the PBCS provides better initial columbic efficiency of 87.1% with the first discharge capacity of 1988.9 mAh g-1. The TEM and operando TXM results display that the PBCS structure significantly protects the nano Si from cracking owing to the high elastic function and intramolecular hydrogen bonding effect of the PBCS. Operando X-ray diffraction is also used to provide the phase information of the Si electrodes. With this novel PBCS-Si material, a high energy density lithium-ion battery contains pure Si can be expected. Reference Li, C.; Shi, T.; Li, D.; Yoshitake, H.; Wang, H., Effect of surface modification on electrochemical performance of nano-sized Si as an anode material for Li-ion batteries. RSC Advances 2016, 6 (41), 34715-34723.Gao, Y.; Yi, R.; Li, Y. C.; Song, J.; Chen, S.; Huang, Q.; Mallouk, T. E.; Wang, D., General Method of Manipulating Formation, Composition, and Morphology of Solid-Electrolyte Interphases for Stable Li-Alloy Anodes. J Am Chem Soc 2017, 139 (48), 17359-17367. Figure 1

Structural analysis of high-energy implanted Ni atoms into Si(100) by X-ray absorption fine structure spectroscopy

Ni silicide synthesis by Ni ion beam irradiation into Si attracts attention due to its advantages including the ability of formation of local structures, the controllability of ion beams, the formability of silicide without heat treatment and the high reproducibility of the resulting specimen. In this work, we investigate the local atomic structure of Si implanted with 3.0 MeV Ni+ ions. Analysis of Ni K-edge fluorescent-yield extended X-ray absorption fine structure reveals that Ni atoms have mixed structure of metallic-like face-centered cubic Ni and NiSi2 phases at the initial stage of the irradiation and the formation of NiSi2 promotes significantly with the ion fluence above 1015 ions⋅cm−2. With consideration of the agreement between the ion fluence threshold for the structural transition and the critical Si-amorphization fluence (7.1 × 1014 ions⋅cm−2), it is concluded that the amorphization of Si plays an important role in the synthesis of the NiSi2 phase in Ni+-irradiated Si.

Parameters optimization of heterojunction ZnSe/CdS/CIGS/Si solar cells using SCAPS-1D software

It is required to simulate the performance of a photovoltaic solar cell performance to enhance it. Simulation optimization has the benefit of being inexpensive and straightforward, and it allows us to identify the optimum parameters that contribute to the enhancement of the cell. An alternative ZnSe/CdS/CIGS/Si structure has been presented using a solar cell capacitance simulator (SCAPS-1D). This paper aims to increase device efficiency by improving the physical characteristics of the many layers involved in cell realisation. We also tried to investigate the variation of electrical characteristics such as Voc, Jsc, , and FF with the changes in material parameters, notably the absorber layer thickness (CIGS, p-Si) (CIGS, p-Si). On the other hand, the temperature dependency has been simulated to guide device manufacturers to attain higher efficiency in varied temperature circumstances. The calculation result shows that excellent performance can be reached by varying the parameters, and the highest efficiency (24,94 %) of the solar cell can be reached under certain conditions, where the thicknesses of ZnSe, CdS, CIGS, and Si are 0.2m, 0.09m, 1.4m, and 0.6m respectively and for the optimal value of temperature equal to 295K.

Near-infrared narrow-band minus filter based on a Mie magnetic dipole resonance.

The traditional minus filter is composed of many layers of thin films, which makes it difficult and complicated to manufacture. It is sensitive to incident light angle and polarization. Here, we propose a near-infrared narrow-band minus filter with a full width at half maximum around 5 nm made of all-dielectric Si-SiO2 structures without any ohmic loss. The stop band transmittance of the proposed filter is close to 0, while its broad pass band transmittance is as high as 90% in the work wavelength range. Theoretical analysis shows that the transmission dip originated from magnetic dipole resonance: Its position can be tuned from 1.3 µm to 1.8 µm by changing the thickness of Si structure, and the proposed structure is insensitive to changes in incident light angle and polarization angle. We further studied its potential applications as a refractive index sensor. The sensitivity of dip1 and dip2 are as high as 953.53 nm/RIU and 691.09 nm/RIU, while their figure of merit is almost unchanged: 59.59 and 115.18, respectively.