Si Nano Research Articles

Novel layout technique for single-event transient mitigation by the groove structure

Based on the damage mechanism of single-event transient (SET) in a MOS device, a new irradiated reinforcement uniaxial strained Si Nano NMOSFET device is further proposed, and the new structure device has no effect on the electrical properties of its original structure. Moreover, the new reinforced device of groove structure can efficiently reduce not only charge collection but also SET pulse widths (WSET). Compared with the conventional NMOS and drain-wall structure, we find that the proposed novel layout technique can provide the best benefit of SET mitigation with a small sacrifice in the effective area. Therefore, the successful development of the research results will play a positive role in promoting the theoretical and technological progress of high-performance radiation-resistant core electronic components and lay a foundation and create conditions for their application in space radiation and nuclear radiation.

Simultaneous broadband and high circular dichroism with two-dimensional all-dielectric chiral metasurface

Abstract Chiral metasurfaces have great potential in various applications such as polarimetric imaging and biomedical recognition. However, simultaneous broadband and high circular dichroism (CD) with high polarization extinction ratio (PER) remains a challenge. Here, we present a novel approach to realize simultaneous broadband and high CD with high PER in the optical communication band using a two-dimensional all-dielectric chiral metasurface. The structure is formed by a two-level chiral structure of split cross (first-order) and trapezoid-shaped (second-order) of Si nano ribs, respectively, in which constructively coupled first- and second-order of chirality occurs, resulting in the broad chiral response in the far field of multipoles excited by incident light of different chiralities. Theoretical results show that a CD in transmission reaching 0.9 (up to 0.993) and a PER exceeding 20 dB (up to 35 dB) over the entire wavelength range from 1.39 to 1.61 μm can be achieved simultaneously, consistent with the experimental results of CD ∼0.9 and PER of 10 dB (up to 19.7 dB). Our design paves the way for chiral metasurfaces toward practical applications in terms of working bandwidth, high CD and PER as well as integrality of the devices in many fields.

Investigation of the interface between LiNbO3 and Si fabricated via room-temperature bonding method using activated Si nano layer

Wafer-level bonding of LiNbO3 and Si has been difficult to achieve owing to the large mismatch in their thermal expansion coefficients, which prevents the use of bonding methods involving annealing. As a solution, we have developed a room-temperature wafer-bonding method that uses an activated Si nanolayer as an adhesive. In this study, we analyzed the bond interface between LiNbO3 and Si that formed via this room-temperature bonding method. The atomic structures of the bonding interface of LiNbO3/Si and the debonded surfaces were investigated in detail. Furthermore, it was found that the bond strength between the activated Si nanolayers and Si was as strong as that of Si/Si bonded using the standard surface-activated bonding method. These findings provide evidence for a strong bond between LiNbO3 and Si at room temperature.

Light‐Driven Polymer‐Based All‐Solid‐State Lithium‐Sulfur Battery Operating at Room Temperature

AbstractPoly(ethylene oxide)‐based polymer all‐solid‐state LiS battery is a promising candidate due to its high specific energy, good processability, and low cost. However, the poor room temperature ionic conductivity limits its further development. Here an innovative photothermal battery technology is proposed to realize the normal operation at room temperature. This design places the 3D Cu substrate with Cu/Si core‐shell structures between Li anode and outer encapsulation glass, so that the light can come in and generate heat efficiently by utilizing the carrier nonradiative recombination of Si nano shell, then the heat quickly transfers to the battery system through Cu core. Once simulated sunlight irradiates, the battery achieves a fast reaction kinetics and superior photothermal conversion, thus realizing a lifespan of over 20 cycles with a capacity of 1089.9 mAh g−1 at 0.2 C. Even on the actual sunlight irradiation, a high discharge/charge capacity of 1065.2/1036.5 mAh g−1 is also reached, indicating an excellent reversible electrochemical process. Moreover, the 3D nanostructure can accommodate the fatal volume variation of lithium and reduce the effective current density, thus suppressing the dendrite nucleation and growth. This study will open the avenue to develop a room temperature polymer all‐solid‐state LiS battery using photothermal technology.

Encapsulation of nano-Si into MOF glass to enhance lithium-ion battery anode performances

Although metal-organic framework (MOF) glasses have exhibited high potential to be applied as anode materials for lithium-ion batteries (LIBs), their electrochemical performances still need to be greatly improved to match the rapid development of green energy technologies. Silicon is a promising candidate for the next generation of LIB anode but suffers from vast volume fluctuations upon lithiation/delithiation. Here, we present a strategy to in situ grow a kind of MOF, namely, cobalt-ZIF-62 (Co(imidazole)1.75(benzimidazole)0.25) on the surface of Si nano particles, and then to transform the thus-derived material into Si@ZIF-glass composite (SiZGC) through melt-quenching. The robust hierarchical structure of the SiZGC based anode exhibits the specific capacity of ∼650 mA h g-1, which is about three times that of pure ZIF glass and about six times that of pristine ZIF crystal at 1 A g-1 after 500 cycles. The origin of this huge enhancement is revealed by performing structural analyses. The ZIF glass phase can not only contribute to lithium storage, but also buffer the volume changes and prevent the aggregation of Si nano particles during lithiation/delithiation processes.

Improved Bacterial Detection Limit via Wet KOH Etching Pathway Enhanced by Laser

Laser with a fixed wavelength (405nm) at different values of intensities (50, 100, 150, 200 mW/cm2) were used to re synthesis Si nano- pillars as based SERS active substrates. The idea was to form SERS devices with high enhancement factor to sense the low residence of bacteria. The results exposed that the topographical features of the Si nano-pillars layer and so, the performance of SERS sensor could be well- controlled via the adjusting of laser intensity through the laser assisted Wet KOH process. The SERS sensing of low concentrations of shows highest bacterial enhancement factor (E.F = 30.1 × 105) and minimum detection limit (LOD = 3.30 Cfu/ml) were realized from high altitude Si nano- pillars; partly populated with three dimensions AgNPs layer, and the use of 150 mW/cm2 laser power density.

Structure and properties of silicon nano- and microparticles obtained by electric-spark dispersion method

Silicon nano- and microparticles obtained using electric-spark dispersion of silicon electrodes and granules in 40 wt% solution of methyl alcohol in water were investigated by ultrasoft X-ray emission spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, scanning and transmission electron microscopies. In addition, the SiLα spectra of obtained silicon particles were modeled by superimposing the spectra of pure silicon and silicon oxide taken in certain weight ratios. It was found that the surfaces of Si nano- and microparticles obtained in 40 wt% solution of methyl alcohol in water are covered with silicon oxide and chemisorbents, while the core consists of crystalline silicon with a cubic face-centered lattice. The silicon nano- and microparticles show potential as an anode material to replace commonly used graphite electrodes. The charge capacity of the electrode based on mixture of Si nano- and microparticles with graphite powder was about 1272 mAh/g after ten cycles.

Phase-only femtosecond optical pulse shaping based on an all-dielectric polarization-insensitive metasurface.

Recently, metasurfaces capable of manipulating the amplitude and the phase of an incident wave in a broad frequency band have been employed for femtosecond optical pulse shaping purposes. In this study, we introduce a phase-only pulse shaper based on an all-dielectric CMOS-compatible polarization-insensitive metasurface, composed of Si nano cylinders sitting on a fused silica substrate. The required phase profile of the metasurface for desired waveforms are calculated using an iterative Fourier transform algorithm, and the performance of the pulse shaper metasurface in implementing the phase masks was assessed using full-wave simulations. Such approach for realizing a polarization-insensitive metasurface-based phase-only pulse shaper has never been investigated to the best of our knowledge. It is demonstrated that the simulated results of the proposed metasurface-based pulse shaper is in great agreement with the results of the algorithm, while exhibiting a very high transmission efficiency. This work indicates yet another exciting but not fully examined application of meta-structures that is the optical pulse shaping.

Controllable synthesization of Au nanoparticles by laser enhanced wet KOH etching process

In Si substrate, anisotropic KOH etchants are mainly utilized to form pyramids like on the Si surface . However, this process is not well controlled way owing to the different and random etching pathway. In this work, we applied laser radiation during the anisotropic KOH wet etching process to modifies the topographical properties of Si substrate, as an efficient,simple and low cost texturing process for Si substrate. This approach employs different laser wavelength to modify the topographical features from a crater like structures to Si nanocrystallites in the form of pillars like structures on the Si surface. In order to investigate the formation of plasmonics species, gold nanoparticles was incorporated into Si surfaces by simple ion reduction process. The Si topographical features was studied with atomic scanning microscopy (AFM) images of Si before and after laser irradiation process. The irradiation with 405 laser wavelength, show the formation of thin and high density of Si nano pillars-like structures compared with more thick depther Si nano pillars like structures layer.

Properties and precipitates of the high strength and electrical conductivity Cu-Ni-Co-Si-Cr alloy

• The (Ni, Co) 2 Si and Cr nano precipitates uniformly distributed in the alloy provide good strength and conductivity. • Excellent ductility is provided because the small lattice mismatch strain between the precipitates and the Cu matrix. • The introduction of deformation twins improves the strength and ductility of the alloy. In this paper, a novel Cu-1.5Ni-1.1Co-0.6Si-0.1Cr (wt.%) alloy with high strength and electrical conductivity was designed. After aging, excellent properties of 857±12 MPa yield strength, 300±8 HV microhardness, 42.8 ± 2.5% IACS conductivity, and 7 ± 0.5% elongation were obtained. According to the atomic structure, part of Ni atoms in Ni 2 Si can be replaced by Co atoms to form nano-precipitates (Ni, Co) 2 Si. The alloy's high strength and conductivity are mainly attributed to the fine and uniformly distributed (Ni, Co) 2 Si and Cr nano precipitates. The alloy strength was also enhanced by twins, dislocations, and grain refining strengthening. Based on the investigations of deformation microstructure and the orientation relationship between the (Ni, Co) 2 Si precipitates and the Cu matrix, the main reason for elongation increase is attributed to the formation of deformation twins and the small lattice mismatch strain at the coherent interfaces of precipitates and the Cu matrix.

Corrosion behavior, microstructure and phase formation of ternary Ni–Ti–Si nano composite synthesised by SHS method

ABSTRACT In this paper, microstructure and phase formation of ternary Ni-Ti-Si nanocomposite synthesized by SHS method with the aim of preparing a precursor of high entropy alloys with bio application was investigated. X-ray diffractometer results show that solid solution, NiTiSi, including all three components was formed within the process. DTA results of mixed powders before synthesis showed that a transformation had happened at approximately 966oC which was related to the ternary solid solution formation. 1652 HV was achieved as the maximum microhardness value. The corrosion behavior of obtained nanocomposites was evaluated by the polarization test at the Zinger solution. The Bode phase diagrams obtained from EIS show that the influence of the porosity on corrosion behavior is higher than that of the phase formation. The best corrosion resistance of 0.06 ohm has been obtained in a sample with 33 wt% of nickel, 35 wt% of titanium, and 32 wt% of silicon.

Laser synthesis of Si nanopillars-based SERS for efficient chlorpyrifos detection

A uniform and high-density Si nanopillars-based SERS layer was synthesized; as an efficient means, for detecting ultra-low concentration of chlorpyrifos. A low (20 %) laser pulse duty cycle of 405 nm wavelength and 600mW/cm2 intensity from a laser diode was used to achieve laser–induced etching. A simple, low-cost, and stable current wave driver circuit was utilized to drive the laser diode. Structural and spectroscopic features of the based SERS layer and AuNPs/Si nano-pillars sensor were studied by scanning probe microscopy, (FESEM) images, x-ray diffraction patterns and Raman spectroscopy. The results revealed that the Si nano-pillars layer provided superior features for creating high density hot spot gaps. A uniform, high population and unique size distributions of (AuNPs) layers on the AuNPs/Si nano-pillars layer were achieved by ion reduction process. The sensor performance displays an excellent detection of chlorpyrifos with an exponential relationship with Raman signal. The highest chlorpyrifos enhancement factor (EF= 1.1*106) with minimum limit of detection (LOD= 22*10−8 M); equivalent to 0.07 mg/Kg, was obtained with Si nano pillars of high value altitude populated with partially three dimensions AuNPs layer. This limit of detection is much lower than the recognized (0.1 mg/kg) value by the European Union.

Effects of Total Dose Radiation on Single Event Effect of the Uniaxial Strained Si Nano NMOSFET

The effect of total dose radiation on the single event effect of uniaxial strained Si Nano channel metal oxide semiconductor field effect transistor (NMOSFET) was studied by TCAD simulation. By comparing the experimental results, the TCAD simulation model of the 50 nm strained Si NMOS device is established. The model is used to simulate the off-state single event effect (V ds = 0.05) of NMOSFET under the total dose radiation. The results show that total dose radiation increases the body potential of NMOSFET devices and intensifies the single event transient process of NMOSFET devices. The transient current increases by 4.88% and the drain charge increases by 29.15% under the total dose of 2KGy, which indicates that the effect of total dose radiation on the single event effect is the main factor affecting the collection of drain charge. Therefore, the experimental results and the established model provide good reference for the study of irradiation reliability of the uniaxial strained Si Nano NMOSFET and the application of strained integrated circuits.

Mass Fabrication of 3D Silicon Nano-/Microstructures by Fab-Free Process Using Tip-Based Lithography.

Methods for the mass fabrication of 3D silicon (Si) microstructures with a100nm resolution are developed using scanning probe lithography (SPL) combined with metal-assisted chemical etching (MACE). Protruding Si structures, including Si nanowires of over 10µm in length and atypical shaped Si nano- and micropillars, are obtained via the MACE of a patterned gold film (negative tone) on Si substrates by dip-pen nanolithography (DPN) with polymer or by nanoshaving alkanethiol self-assembled monolayers (SAMs). Furthermore, recessed Si structures with arbitrary patterning and channels less than 160nm wide and hundreds of nanometers in depth are obtained via the MACE of a patterned gold film (positive tone) on Si substrates by alkanethiol DPN. As an example of applications using protruded Si structures, nanoimprinting in an area of up to a centimeter is demonstrated through 1D and 2D SPL combined with MACE. Similarly, submicrometer polydimethylsiloxane (PDMS) stamps are employed over millimeter-scale areas for applications using recessed Si structures. In particular, the mass production of arbitrarily shaped Si microparticles at submicrometer resolution is developed using silicon-on-insulator substrates, as demonstrated using optical microresonators, surface-enhanced Raman scattering templates, and smart microparticles for fluorescence signal coding.

Controllable formation of plasmonic gold nanoparticles by pulsed laser–induced etching

This work discusses the preparation and formation of macro porous silicon (PSi) with silicon nano pillars; synthesized via laser–induced etching. The role of laser pulse duty cycle (10–100%) was investigated for silicon nano pillars samples creation using laser diode; characterized by its short wavelength (405 nm) and high laser intensity (500 mW/cm2). Morphological and spectroscopic aspects of the Si nanocrystallite sizes and plasmonic Au–NP, surface topography, roughness and thickness of the created layer were investigated by the scanning probe microscopy, photoluminescence measurements, the analysis of (FESEM) images and (XRD) patterns. The results revealed well-regulated Si nano pillars layers after adjusting the laser duty cycle under the same laser intensity and etching time. The histogram of Si nano pillars sizes, surface roughness and altitude of nano pillars within macro PSi created at 20% laser duty cycle showed specific characteristics; due to the minimal heat accumulation within the pillars and limited probability of damaging the pillars’ morphological aspects. The Si nano pillars were employed to synthesize and control the plasmonic features of Au-NPs. The histogram of hotspot regions and plasmonic Au-NPs sizes and their specific surface areas and grain size showed well-controlled structures after adjusting the laser pulse duty cycle.

Using Laser Duty Cycles for Modifying the Performance of Au-NPs/Si Nano Column Hot Spot SERS Sensors

In the current study, the Si nano column layer via pulsed photo chemical etching with different laser pulse duty cycle 30 and 60% using short laser wavelength (405 nm) and laser intensity (100 mW/cm2) was formed and studied. Two types of Si nano column-based plasmonic Au-NP hot spot layers were synthesized and examined successfully as an efficient SERS layer for the detection of the ultra-low concentration of amoxicillin. Si nano columns exposed a great effect on the performance of the Au-NP hot spot SERS sensor showing a strong dependence on the density of the hot spot gaps within the sensitive layer. Enhancement factor (EF) of the Raman signal improved considerably with increasing the density of the hot spot gaps due to the coupling efficiency among the plasmonic Au-NPs and the molecules of amoxicillin within the hot spot regions. EF increased by about four orders of magnitude with decreasing the laser duty cycles due to the increase of the integrated plasmonic Au-NPs into the Si nano column layer.

Silicon based nano-sensors for neutron dosimetry: Proof of concept

Silicon based nano structured thermal neutron detectors are desired to replace the existing neutron detectors since they are small and light, and has enough sensitivity to neutrons. In this work, device geometry has been simulated in SRIM and the radiation induced damages were calculated for 1.47 MeV α particle in a Silicon Nano wire (SiNW) having varying thickness and found out that the ideal thickness ranges from 0.5 mm to 1 mm. It has also been found that, for a single Si nano wire, the expected efficiency, η is 10.17%. Thus for ‘n’ number of SiNWs, the expected efficiency is ‘n × η’, which will be a remarkable increase in the efficiency when compared to the reported present thermal neutron detectors. A planar Silicon detector was also analyzed at the same time for the efficiency comparison and found that it could differentiate the signals of both 7Li and alpha pulses separately with a better resolution.

Surface-Enhanced IR-Absorption Microscopy of Staphylococcus aureus Bacteria on Bactericidal Nanostructured Si Surfaces.

Surface-enhanced IR absorption (SEIRA) microscopy was used to reveal main chemical and physical interactions between Staphylococcus aureus bacteria and different laser-nanostructured bactericidal Si surfaces via simultaneous chemical enhancement of the corresponding IR-absorption in the intact functional chemical groups. A cleaner, less passivated surface of Si nanoripples, laser-patterned in water, exhibits much stronger enhancement of SEIRA signals compared to the bare Si wafer, the surface coating of oxidized Si nanoparticles and oxidized/carbonized Si (nano) ripples, laser-patterned in air and water. Additional very strong bands emerge in the SEIRA spectra on the clean Si nanoripples, indicating the potential chemical modifications in the bacterial membrane and nucleic acids during the bactericidal effect.

SiGe/AsSb bilayer heterostructures: structural characteristics and tunable electronic properties

Tunable band gap along with high carrier mobility are attractive characteristics for high speed nano electronic device applications. In this work we studied the structural and electronic properties of atomically thin silicon germanide (SiGe) and antimony arsenide (AsSb) heterobilayers using first principle calculations within density functional theory. Monolayer SiGe is a semimetal with a Dirac cone at the K point of the Brillouin zone (BZ) which combines superior properties of germanene and synthesis advantages of silicene. The study shows that a considerable band gap (90–459 meV) is introduced in SiGe when modulated by monolayer AsSb without degrading the carrier mobility. Moreover AsSb introduces negligible lattice mismatch in optimized heterobilayers which is favorable for synthesis purposes. We studied the density of states and space charge distribution to investigate the mechanism of the band gap opening and interlayer binding. Finally we modulated the band gap at K the point of the BZ efficiently by applying biaxial strain and also by changing the interlayer spacing. The calculated electron effective mass as a function of strain reveals that linear energy dispersion relation is preserved and the effective mass remains significantly small within the strained structure. The results predict that SiGe/AsSb heterobilayers can be an excellent choice in Si and Ge-based nano electronics and spintronic applications

Influence of gamma ray radiation on two-dimensional sub-threshold current of strained Si nano NMOSFET

ABSTRACTThe carrier transport in uniaxial strained Si N channel metalvn oxide semiconductor field effect transistor (NMOSFET) irradiated by gamma rays is analyzed. Based on the total dose irradiation effect, an analytical model of two-dimensional sub-threshold current for differential capacitance of uniaxial strained Si Nano NMOSFET is established. Based on this model, numerical calculation is carried out by MATLAB. The influence of geometric parameters and total dose on differential capacitance is simulated. Meanwhile, the simulation results match the experiment result very well, which validates the accuracy of the model. Therefore, the model provides a good reference for the irradiation reliability of uniaxial strained Si nano NMOSFET and the application of strained integrated circuits.