Solid-State Lithium Batteries with Ultrastable Cyclability: An Internal-External Modification Strategy.

A commonly used strategy to tackle the unstable interfacial problem between Li1.3Al0.3Ti1.7(PO4)3 (LATP) and lithium (Li) is to introduce an interlayer. However, this strategy has a limited effect on stabilizing LATP during long-term cycling or under high current density, which is due in part to the negative impact of its internal defects (e.g., gaps between grains (GBs)) that are usually neglected. Here, control experiments and theoretical calculations show clearly that the GBs of LATP have higher electronic conductivity, which significantly accelerates its side reactions with Li. Thus, a simple LiCl solution immersion method is demonstrated to modify the GBs and their electronic states, thereby stabilizing LATP. In addition to LiCl filling, composite solid polymer electrolyte (CSPE) interlayering is concurrently introduced at the Li/LATP interface to realize the internal-external dual modifications for LATP. As a result, electron leakage in LATP can be strictly inhibited from its interior (by LiCl) and exterior (by CSPE), and such dual modifications can well protect the Li/LATP interface from side reactions and Li dendrite penetration. Notably, thus-modified Li symmetrical cells can achieve ultrastable cycling for more than 3500 h at 0.4 mA cm-2 and 1500 h at 0.6 mA cm-2, among the best cycling performance to date.

Silicon Nanowire Array Weaved by Carbon Chains for Stretchable Lithium-Ion Battery Anode.

To manufacture flexible batteries, it can be a challenge for silicon base anode materials to maintain structural integrity and electrical connectivity under bending and torsion conditions. In this work, 1D silicon nanowire array structures combined with flexible carbon chains consisting of short carbon nanofibers (CNFs) and long carbon nanotubes (CNTs) are proposed. The CNFs and CNTs serve as chain joints and separate chain units, respectively, weaving the well-ordered Si nanowire array into a robust and integrated configuration. The prepared flexible and stretchable silicon array anode exhibits excellent electrochemical performance during dynamic operation. A high initial specific capacity of 2856 mAh g-1 is achieved. After 1000 cycles, a capacity retention of 60% (1602 mAh g-1) is maintained. Additionally, the capacity attenuation is less than 1% after 100 bending cycles. This excellent cycling stability is obtained with a high Si loading of 6.92 mg cm-2. This novel approach offers great promise for the development of high-loading flexible energy-storage devices.

Effect of the bonding layer and multigrading layers on the performance of a wafer-bonded InGaAs/Si single-photon detector.

A wafer-bonded InGaAs/Si avalanche photodiode (APD) at a wavelength of 1550 nm was theoretically simulated. We focused on the effect of the I n 1-x G a x A s multigrading layers and bonding layers on the electric fields, electron and hole concentrations, recombination rates, and energy bands. In this work, I n 1-x G a x A s multigrading layers inserted between Si and InGaAs were adopted to reduce the discontinuity of the conduction band between Si and InGaAs. A bonding layer was introduced at the InGaAs/Si interface to isolate the mismatched lattices to achieve a high-quality InGaAs film. In addition, the bonding layer can further regulate the electric field distribution in the absorption and multiplication layers. The wafer-bonded InGaAs/Si APD, structured by a polycrystalline silicon (poly-Si) bonding layer and I n 1-x G a x A s multigrading layers (x changes from 0.5 to 0.85), displayed the highest gain-bandwidth product (GBP). When the APD operates in Geiger mode, the single-photon detection efficiency (SPDE) of the photodiode is 20%, and the dark count rate (DCR) is 1 MHz at 300 K. Moreover, one finds that the DCR is lower than 1 kHz at 200 K. These results indicate that high-performance InGaAs/Si SPAD can be achieved through a wafer-bonded platform.

Scalable fabrication of self-assembled GeSn vertical nanowires for nanophotonic applications.

In this work, scalable fabrication of self-assembled GeSn vertical nanowires (NWs) based on rapid thermal annealing (RTA) and inductively coupled-plasma (ICP) dry etching was proposed. After thermal treatment of molecular-beam-epitaxy-grown GeSn, self-assembled Sn nanodots (NDs) were formed on surface and the spontaneous emission from GeSn direct band was enhanced by ∼5-fold. Employing the self-assembled Sn NDs as template, vertical GeSn NWs with a diameter of 25 ± 6 nm and a density of 2.8 × 109 cm-2 were obtained by Cl-based ICP dry etching technique. A prototype GeSn NW photodetector (PD) with rapid switching ability was demonstrated and the optoelectronic performance of Ge NW PD was systematically studied. The GeSn NW PD exhibited an ultralow dark current density of ∼33 nA/cm2 with a responsivity of 0.245 A/W and a high specific detectivity of 2.40 × 1012 cm Hz1/2 W-1 at 1550 nm under -1 V at 77 K. The results prove that this method is prospective for low-cost and scalable fabrication of GeSn NWs, which are promising for near infrared or short wavelength infrared nanophotonic devices.

Spatially modulated femtosecond laser direct ablation-based preparation of ultra-flexible multifunctional copper mesh electrodes and its application.

Multifunctional electrodes possess superior properties such as high photoelectric properties and high stability. Laser manufacturing process is one of the widely used method for electrode fabrication. However, the current multifunctional electrode laser manufacturing process suffers from low fabrication speed. Here, we report a high-efficiency laser digital patterning process to fabricate copper-based flexible transparent conducting electrodes. By using a spatially modulated, one single laser spot is modulated into an array of spots with equal intensity, and the fabrication speed can be improved by more than 20 times over the traditional single pulse processing. In addition, copper mesh electrodes with a high photoelectric property have been fabricated. A transparent touch screen panel and multifunctional windows are fabricated with transparent electrodes to demonstrate their use in vehicle defogging, portable heating, and wearable devices.

Clinical study on multi-focused laser in the treatment of vulvar lichen sclerosus.

Objective: To investigate the clinical effect of Multi-focused (MF) laser in the treatment of vulvar lichen sclerosus (VLS). Methods: In this single-center, randomized controlled trial, we compared the effect of fractionated MF laser with other treatments on patients with biopsy-proven VLS. Patients with VLS were enrolled in this study and randomly divided into three groups. Patients in the experimental group were treated with a CO2 laser, control group 1 was treated with radiofrequency, and control group 2 was treated topically with glucocorticoids and soaking with Chinese patent medicine. The pruritus degree, skin elasticity, skin color, lesion scope, and total score were compared before treatment, at one month after treatment, and three months after treatment. Results: One month after treatment, the pruritus degree, skin elasticity, skin color, lesion scope, and total score decreased in the experimental group, and the differences were statistically significant (P < 0.05). In control group 1, the differences in pruritus degree, skin color, and total score were statistically significant (P < 0.05), but the differences in skin elasticity and lesion scope were not statistically significant (P > 0.05). In control group 2, the differences in pruritus degree and total score were statistically significant (P < 0.05), but the differences in skin elasticity, skin color, and lesion scope were not statistically significant (P > 0.05). At one month after the end of treatment, the differences in pruritus degree, skin elasticity, skin color, lesion scope, and total score among the three groups were not statistically significant. At three months after the end of treatment, the differences in the scores of the five indicators were statistically significant. Conclusion: For the three treatment methods for VLS, topical corticosteroids + traditional Chinese medicine can quickly relieve itching symptoms in patients, but it cannot significantly improve skin elasticity, skin color, and lesion scope, and VLS easily relapses after treatment. Radiofrequency can improve itching symptoms and skin color but has poor effects on the change of skin elasticity and lesion scope. Multi-focused laser treatment can alleviate the degree of pruritus, improve skin color and elasticity, and narrow the lesion scope, and VLS will not relapse within three months after treatment.

On the Interface Design of Si and Multilayer Graphene for a High-Performance Li-Ion Battery Anode.

Si/multilayer graphene (mG) is a promising candidate for the next-generation Li-ion battery anode. The highly ordered mG shows intrinsic good stability against the liquid electrolyte and its flexibility to accommodate volume change. Until now, reducing the growth temperature and thus engineering the interphase are a very important research area, but only few studies have been reported. Herein, for the first time, the mG is grown with the Al2O3 catalyst at a relatively low temperature of 750 °C, while the thickness is controlled to 2 nm. The growth of mG obeys the Stranski-Krastanov mechanism. Applying a rapid cooling process, a silicon oxycarbide (SiOC) interlayer is in situ-fabricated between the mG coating layer and Si core. The SiOC interlayer is demonstrated to accommodate the volume change of Si and enable faster lithium ion transportation than mG. Taking synergetic advantages of the mG coating layer and SiOC interphase, the cycling stability significantly improved, and a high specific capacity of 990 mA h/g is obtained at 1 A/g after 500 cycles in half cells. A high rate performance of 1164.5 mA h/g at 4 A/g is achieved. Tested in a 1.8 A h pouch cell with LiNi0.5Mn0.3Co0.2O2 (NMC532) as the cathode, the cell delivers a specific energy of ∼380 W h/kg. The capacity retentions are 93% and 78% after 100 cycles and 200 cycles, respectively. Our work highlights the importance of the interphase design of Si/mG composite anodes, which could also be extended to various core-shell materials in energy storage materials.

Fabrication of flexible transparent Ag square-shaped mesh electrode by top-flat nanosecond laser ablation.

We report a facile top-flat square nanosecond (ns) laser direct writing ablation technique in a thin silver film substrate to fabricate the silver square-shaped cell structure of flexible transparent electrodes. Square silver cell structures feature smooth surface morphology, excellent edge definition, mechanical stability, strong adhesion to the substrate, and favorable resistance and transparency. In particular, this strategy enables fabrication of a high square-shaped cell areal density (ablated square cell to the total area) Ag mesh, substantially improving transparency ($ {\gt} {85}\% $>85%) without considerably sacrificing conductivity ($ {\lt} {5}\;\Omega \;{{\rm sq}^{ - 1}}$<5Ωsq-1 unit of resistance). Consequently, the proposed metallic square-shaped structure shows compatibility with a polyethylene naphthalate flexible substrate for silver-based wearable electronic devices without any protective layer over the electrodes.

Broadband 400-2400†nm Ge heterostructure nanowire photodetector fabricated by three-dimensional Ge condensation technique.

A 2.7% tensile strained Ge/SiGe heterostructure nanowire (NW) is in-situ fabricated by a three-dimensional Ge condensation method. The NW metal-semiconductor-metal (MSM) photodetector demonstrates an ultra-broadband detection wavelength of 400-2400 nm, showing a high responsivity of >3.46×102 A/W with a photocurrent gain of >4.32×102 at 1550 nm under -2 V. A high normalized photocurrent to dark current ratio (NPDR) of 1.88×1011 W-1 at 1550 nm under -1 V is achieved. The fully complementary metal-oxide-semiconductor (CMOS) compatible, simple and scalable process suggest that the Ge heterostructure NW is promising for low cost, high performance near-infrared or short wavelength infrared focal plane array applications.

Low Reflection and Low Surface Recombination Rate Nano-Needle Texture Formed by Two-Step Etching for Solar Cells.

In this study, needle-like and pyramidal hybrid black silicon structures were prepared by performing metal-assisted chemical etching (MACE) on alkaline-etched silicon wafers. Effects of the MACE time on properties of the black silicon wafers were investigated. The experimental results showed that a minimal reflectance of 4.6% can be achieved at the MACE time of 9 min. The height of the nanostructures is below 500 nm, unlike the height of micrometers needed to reach the same level of reflectance for the black silicon on planar wafers. A stacked layer of silicon nitride (SiNx) grown by inductively-coupled plasma chemical vapor deposition (ICPCVD) and aluminum oxide (Al2O3) by spatial atomic layer deposition was deposited on the black silicon wafers for passivation and antireflection. The 3 min MACE etched black silicon wafer with a nanostructure height of less than 300 nm passivated by the SiNx/Al2O3 layer showed a low surface recombination rate of 43.6 cm/s. Further optimizing the thickness of ICPCVD-SiNx layer led to a reflectance of 1.4%. The hybrid black silicon with a small nanostructure size, low reflectance, and low surface recombination rate demonstrates great potential for applications in optoelectronic devices.

Enhanced Si Passivation and PERC Solar Cell Efficiency by Atomic Layer Deposited Aluminum Oxide with Two-step Post Annealing.

In this study, aluminum oxide (Al2O3) films were prepared by a spatial atomic layer deposition using deionized water and trimethylaluminum, followed by oxygen (O2), forming gas (FG), or two-step annealing. Minority carrier lifetime of the samples was measured by Sinton WCT-120. Field-effect passivation and chemical passivation were evaluated by fixed oxide charge (Qf) and interface defect density (Dit), respectively, using capacitance-voltage measurement. The results show that O2 annealing gives a high Qf of - 3.9 × 1012 cm-2, whereas FG annealing leads to excellent Si interface hydrogenation with a low Dit of 3.7 × 1011 eV-1 cm-2. Based on the consideration of the best field-effect passivation brought by oxygen annealing and the best chemical passivation brought by forming gas, the two-step annealing process was optimized. It is verified that the Al2O3 film annealed sequentially in oxygen and then in forming gas exhibits a high Qf (2.4 × 1012 cm-2) and a low Dit (3.1 × 1011 eV-1 cm-2), yielding the best minority carrier lifetime of 1097 µs. The SiNx/Al2O3 passivation stack with two-step annealing has a lifetime of 2072 µs, close to the intrinsic lifetime limit. Finally, the passivated emitter and rear cell conversion efficiency was improved from 21.61% by using an industry annealing process to 21.97% by using the two-step annealing process.

Temperature-Dependent HfO2/Si Interface Structural Evolution and its Mechanism.

In this work, hafnium oxide (HfO2) thin films are deposited on p-type Si substrates by remote plasma atomic layer deposition on p-type Si at 250 °C, followed by a rapid thermal annealing in nitrogen. Effect of post-annealing temperature on the crystallization of HfO2 films and HfO2/Si interfaces is investigated. The crystallization of the HfO2 films and HfO2/Si interface is studied by field emission transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and atomic force microscopy. The experimental results show that during annealing, the oxygen diffuse from HfO2 to Si interface. For annealing temperature below 400 °C, the HfO2 film and interfacial layer are amorphous, and the latter consists of HfO2 and silicon dioxide (SiO2). At annealing temperature of 450-550 °C, the HfO2 film become multiphase polycrystalline, and a crystalline SiO2 is found at the interface. Finally, at annealing temperature beyond 550 °C, the HfO2 film is dominated by single-phase polycrystalline, and the interfacial layer is completely transformed to crystalline SiO2.

Scalable Engineering of Bulk Porous Si Anodes for High Initial Efficiency and High-Areal-Capacity Lithium-Ion Batteries.

Nano-Si has been long-hampered in its use for practical lithium battery anodes due to its intrinsic high surface area. To improve the Coulombic efficiency and areal mass loading, we extend the starting materials from nano-Si to photovoltaic waste Si powders (∼1.5 µm). Unique morphology design and interfacial engineering are designed to overcome the particle fracture of micrometer Si. First, we develop a Cu-assisted chemical wet-etching method to prepare micrometer-size bulk-porous Si (MBPS), which provides interconnected porous space to accommodate volume expansion. In addition, a monolithic, multicore, interacting MBPS/carbonized polyacrylonitrile (c-PAN) electrode with strong interfacial Si-N-C is designed to improve the interparticle electrical conductivity during volume expansion and shrinkage. Furthermore, intermediate Si nanocrystals are well-maintained during the lithiation of MBPS, which facilitates the reversibility of lithiation-delithiation process. As a result, the MBPS/c-PAN electrodes exhibit a reversible specific capacity of 2126 mAh g-1 with a high initial Coulombic efficiency of 92%. Moreover, even after increasing the capacity loading to 3.4 mAh cm-2, the well-designed electrode shows a capacity retention of 94% in the first 50 cycles at a current density of 0.2 A g-1 with deep lithiation and delithiation processes between 0.005 and 2.5 V.

Pulse laser-induced size-controllable and symmetrical ordering of single-crystal Si islands.

Optically electric- and magnetic resonance-induced dielectric nanostructures have garnered significant attention due to applications as tunable electronic and optoelectronic device. In this letter, we describe an ultrafast and large-area method to construct symmetrical and single-crystal Si island structures directly on Si substrates by a pulse laser dewetting method. The tunable surface electric field intensity distribution could convert the stochastic dewetting process into a deterministic process (classical dipole mode and Mie resonance dipole mode) on predefined Si pit arrays via laser dewetting. Under this condition, these pre-patterned Si substrate structures not only induced high spatial ordering of islands, but also improved their size uniformity. By adjusting the laser fluence, the diameter of the single-crystal Si islands could be selected in the range 41.7-147.1 nm.

Monolithically Integrated Self-Charging Power Pack Consisting of a Silicon Nanowire Array/Conductive Polymer Hybrid Solar Cell and a Laser-Scribed Graphene Supercapacitor.

Owing to the need for portable and sustainable energy sources and the development trend for microminiaturization and multifunctionalization in the electronic components, the study of integrated self-charging power packs has attracted increasing attention. A new self-charging power pack consisting of a silicon nanowire array/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) hybrid solar cell and a laser-scribed graphene (LSG) supercapacitor has been fabricated. The Si nanowire array/PEDOT:PSS hybrid solar cell structure exhibited a high power conversion efficiency (PCE) of 12.37%. The LSG demonstrated excellent energy storage capability for the power pack, with high current density, energy density, and cyclic stability when compared to other supercapacitor electrodes such as active carbon and conducting polymers. The overall efficiency of the power unit is 2.92%.

Low dark current broadband 360-1650 nm ITO/Ag/n-Si Schottky photodetectors.

This work designed an ITO/Ag/n-Si Schottky photodetector with broad wavelength detection and low dark current. The introduction of Ag interfacial layer and post rapid thermal annealing dramatically increase the barrier height of ITO/n-Si Schottky diode by 0.32 eV, leading to the 2300 × reduction of dark current. A well-behaved ITO/Ag (8 nm)/n-Si Schottky diode with a high rectification ratio ( ± 1 V) of 4 × 105 and low dark current (-1 V) of 9.2 nA was achieved. Such low dark current device spontaneously provides high sensitivity for visible/near infrared wavelength detection, in which substantial responsivity for wavelengths from 360 to 1650 nm was realized through both inter-band and internal photoemission. The design here provides an encouraging strategy for monolithically integrated pure Si photodetectors operating at long wavelength up to 1650 nm.

Thyroid cancer 1 (C8orf4) shows high expression, no mutation and reduced methylation level in lung cancers, and its expression correlates with ß-catenin and DNMT1 expression and poor prognosis.

Thyroid cancer 1 (TC1, C8orf4) plays important roles in tumors. The aim of this study was to examine the protein expression levels, methylation status, and mutational status of TC1 (C8orf4) in lung cancers, and investigate the correlation between TC1, other members of the Wnt signaling pathway, and lung cancer. TC1 expression levels were assessed via immunohistochemical staining in 179 cases of lung cancer. ß-catenin, TCF4, Axin, Disabled-2, Chibby, and DNA methyltransferase-1 (DNMT1) expressions were also examined. Bisulfite sequencing PCR analysis was used to examine the methylation status of the C8orf4 locus, while PCR analysis and direct sequencing were used to determine its mutational status. We found high TC1 expression correlated with poor differentiation, advanced TNM stage, lymphatic metastasis, and poor prognosis in lung cancer patients. TC1 expression also correlated with ß-catenin and DNMT1 expressions. No mutations in C8orf4 were detected. However, methylation levels of C8orf4 in lung cancers were lower than in corresponding normal lung tissues. In conclusion, high TC1 expression is implicated in lung cancer progression and correlates with poor prognosis in lung cancer. Reduced methylation levels might be responsible for the elevated TC1 expression levels. TC1, ß-catenin, and DNMT1 can synergistically activate Wnt/ß-catenin signaling in lung cancers.

Design of wafer-bonded structures for near room temperature Geiger-mode operation of germanium on silicon single-photon avalanche photodiode.

We investigate the effect of temperature on the single-photon properties of four germanium/silicon (Ge/Si) single-photon avalanche photodiodes (SPADs), which are fabricated by Ge-on-Si direct epitaxial growth, Ge-on-Si two-step epitaxial growth, Ge/Si direct wafer bonding, and Si/Si hydrophobic bonding, respectively. It is found that the wafer-bonded Ge/Si SPAD exhibits extremely low dark current and dark count rate (DCR) compared with the epitaxial ones at 250 and 300 K. This implies that the wafer-bonding technique is a possible candidate for the fabrication of Ge/Si SPAD, which can be operated at near room temperature. Additionally, due to the low DCR and high operation temperature, the wafer-bonded Ge/Si SPAD shows extremely high pulse repetition rate (∼28 MHz in theory for DCR=108 Hz). That is, the wafer-bonded Ge/Si SPAD can be used in a high-speed field. Finally, the effect of voltage pulse width, number of photons per pulse, and hold-off time on the performance of the wafer-bonded Ge/Si SPAD at different temperatures is also clarified.

Surface Passivation of Silicon Using HfO2 Thin Films Deposited by Remote Plasma Atomic Layer Deposition System.

Hafnium oxide (HfO2) thin films have attracted much attention owing to their usefulness in equivalent oxide thickness scaling in microelectronics, which arises from their high dielectric constant and thermodynamic stability with silicon. However, the surface passivation properties of such films, particularly on crystalline silicon (c-Si), have rarely been reported upon. In this study, the HfO2 thin films were deposited on c-Si substrates with and without oxygen plasma pretreatments, using a remote plasma atomic layer deposition system. Post-annealing was performed using a rapid thermal processing system at different temperatures in N2 ambient for 10 min. The effects of oxygen plasma pretreatment and post-annealing on the properties of the HfO2 thin films were investigated. They indicate that the in situ remote plasma pretreatment of Si substrate can result in the formation of better SiO2, resulting in a better chemical passivation. The deposited HfO2 thin films with oxygen plasma pretreatment and post-annealing at 500 °C for 10 min were effective in improving the lifetime of c-Si (original lifetime of 1 µs) to up to 67 µs.

Voltage sharing effect and interface state calculation of a wafer-bonding Ge/Si avalanche photodiode with an interfacial GeO2 insulator layer.

The tunneling effect and interface state in the p-Ge/GeO2p-Si structure of a wafer-bonding Ge/Si avalanche photodiode (APD) are investigated. It is found that the thin interfacial GeO2 layer (1-2 nm) formed by the hydrophilic reaction at the wafer-bonding interface significantly affects the performance of the Ge/Si APD. With the increase of the GeO2 thickness, the dark current of the Ge/Si APD decreases enormously due to the blocking effect of this GeO2 layer. Owing to the carrier accumulation in Ge layer under illumination condition, the voltage sharing effect of the GeO2 layer (thicker) becomes serious, leading to the absence of the electric field in Ge layer. The photon-generated electrons at Ge/GeO2 interface can be captured and released by the interface states at certain reverse bias. This can adjust the avalanche current of the Ge/Si APD. The stronger interface recombination induced by the larger interface state density (ISD) results in the decrease of the electric field in Ge layer. This increases the transit time of carriers, which in turn decreases the 3dB-bandwidth. Due to the drastic increase of the dark current (larger ISD), the gain of the Ge/Si APD decreases.