Nano silica aerogel-induced formation of an organic/alloy biphasic interfacial layer enables construction of stable high-energy lithium metal batteries

Lithium metal batteries represent promising candidates for high-energy-density batteries, however, many challenges must still be overcome,e.g., interface instability and dendrite growth. In this work, nano silica aerogel was employed to generate a hybrid film with high lithium ion conductivity(0.6 mS cm^(-1)at room temperature) via an in situ crosslinking reaction. TOF-SIMS profile analysis has revealed conversion mechanism of hybrid film to Li–Si alloy/Li F biphasic interface layer, suggesting that the Li–Si alloy and Li F-rich interface layer promoted rapid Li+transport and shielded the Li anodes from corrosive reactions with electrolyte-derived products. When coupled with nickel-cobalt-manganese-based cathodes, the batteries achieve outstanding capacity retention over 1000 cycles at 1 C. Additionally the developed film coated on Li enabled high coulombic efficiency(99.5%) after long-term cycling when coupled with S cathodes. Overall, the results presented herein confirm an effective strategy for the development of high-energy batteries.

Influence of the lattice parameter of the AlN buffer layer on the stress state of GaN film grown on(111)Si

GaN films grown on(111)Si substrate with different lattice parameters of the AlN buffer layer by metal–organic chemical vapor deposition are studied.The stress states obtained by different test methods are compared and it is found that the lattice parameter of the AlN buffer layer may have a significant effect on the stress state in the initial stage of subsequent GaN film growth.A larger compressive stress is beneficial to improved surface morphology and crystal quality of GaN film.The results of further orthogonal experiments show that an important factor affecting the lattice parameter is the growth rate of the AlN buffer layer.This work may be helpful for realizing simple GaN-on-Si structures and thus reducing the costs of growth processes.

Sub-nano Layers of Li, Be, and Al on the Si(100) Surface: Electronic Structure and Silicide Formation

Within the framework of the density functional theory and the pseudopotential method,the electronic structure calculations of the“metal-Si(100)”systems with Li,Be and Al as metal coverings of one to four monolayers(ML)thickness,were carried out.Calculations showed that band gaps of 1.02 eV,0.98 eV and 0.5 eV,respectively,appear in the densities of electronic states when the thickness of Li,Be and Al coverings is one ML.These gaps disappear with increasing thickness of the metal layers:first in the Li-Si system(for two ML),then in the Al-Si system(for three ML)and then in the Be-Si system(for four ML).This behavior of the band gap can be explained by the passivation of the substrate surface states and the peculiarities of the electronic structure of the adsorbed metals.In common the results can be interpreted as describing the possibility of the formation of a two-dimensional silicide with semiconducting properties in Li-Si(100),Be-Si(100)and Al-Si(100)systems.

Formation mechanism of periodic layered structure in Ni_3Si/Zn system

The formation of periodic layered structure in Ni3Si/Zn diffusion couples with Zn in vapor or liquid state was investigated by SEM-EDS, FESEM and XRD. The results show that the diffusion path in solid-liquid reaction is Ni3Si/（T＋γ）/γ/…T/γ/Ni4Zn12Si3/γ/…Ni4Zn12Si3/γ/Ni4Zn12Si3/δ…/Ni4Zn12Si3/δ/liquid-Zn, and the diffusion path in solid-vapor reaction is Ni3Si/θ/（T＋γ）/γ/…/T/γ/…T/γ/vapor-Zn. With increasing Zn diffusion flux, the diffusion reaction path moves toward the Zn-rich direction, and the distance from the Ni3Si substrate to the periodic layer pair nearest to the interface decreases. In the initial stage of both reactions,γphase nucleates and grows within T matrix phase at first, and then conjuncts together to form a band to reduce the surface energy. Based on the experimental results and diffusion kinetics analysis, the microstructure differences were compared and the formation mechanism of the periodic layered structure in Ni3Si/Zn system was discussed.

Composite electron transport layer for efficient N-I-P type monolithic perovskite/silicon tandem solar cells with high open-circuit voltage

Perovskite/silicon tandem solar cells(PSTSCs) have exhibited huge technological potential for breaking the Shockley-Queisser limit of single-junction solar cells. The efficiency of P-I-N type PSTSCs has surpassed the single-junction limit, while the performance of N-I-P type PSTSCs is far below the theoretical value. Here, we developed a composite electron transport layer for N-I-P type monolithic PSTSCs with enhanced open-circuit voltage(VOC) and power conversion efficiency(PCE). Lithium chloride(Li Cl) was added into the tin oxide(SnO_(2)) precursor solution, which simultaneously passivated the defects and increased the electron injection driving force at the electron transfer layer(ETL)/perovskite interface.Eventually, we achieved monolithic PSTSCs with an efficiency of 25.42% and V_(OC) of 1.92 V, which is the highest PCE and VOCin N-I-P type perovskite/Si tandem devices. This work on interface engineering for improving the PCE of monolithic PSTSCs may bring a new hot point about perovskite-based tandem devices.

Fabrication of ceramic layer on an Al-Si alloy by MAO process

The MAO (Micro-Arc Oxidation) process is applied to a eutectic Al-Si alloy(Al-12.0 percent Si-l.0 percent Cu-0.9 percent Mg (mass fraction)). The oxide ceramic layer wasfabricated with about 220 mum thickness and 3000 Hv micro-hardness. By XRD (X-ray diffractometry)and DSC (differential scanning calorimetry) analyses, the oxide layer consists of amorphous Al_2O_3,which is distinct from the results reported by the other researchers. The SEM photographs of suchlayer show that the layer is fixed tightly on the substrate alloy. So this alloy can he used in thehigh temperature and friction environment alter it is treated with such process.

Reduction of Dislocations in GaN Epilayer Grown on Si （111） Substrates using a GaN Intermedial Layer

GaN intermedial layers grown under different pressures are inserted between GaN epilayers and AIN/Si（111） substrates. In situ optical reflectivity measurements show that a transition from the three-dimensional （3D） mode to the 2I） one occurs during the GaN epilayer growth when a higher growth pressure is used during the preceding GaN intermedial layer growth, and an improvement of the crystalline quality of GaN epilayer will be made. Combining the in situ reflectivity and transmission electron microscopy （TEM） measurements, it is suggested that the lateral growth at the transition of growth mode is favourable for bending of dislocation lines, thus reducing the density of threading dislocations in the epilayer.

Acheivement of Nano-Scale SiGe Layer with Discrete Ge Mole Fraction Profile Using Batch-Type HVCVD

The strained Si grown on the relaxed SiGe-on-insulator C-MOSFET's is a promising device for the future system LSI devices with the design rule of sub-micron. The achievement of the discrete Ge mole fraction in the SiGe layer is a key engineering in low-temperature SiGe epitaxial growth using HVCVD. The pre-flow of GeH4 gas enhanced the Ge mole fraction and SiGe layer thickness. In addition, the Ge mole fraction and SiGe layer thickness increases with the gas ratio of GeH4/SiH4 + GeH4, process temperature, and gas flow time. However, the haze was produced if the Ge mole fraction is above 22wt%. The discrete-like Ge mole fraction with 22 wt% in 10 nm SiGe layer was obtained by the pre-flow of GeH4 for 10 s, the mixture gas ratio of GeH4/SiH4 + GeH4 of 67%, and the gas flow time for 150 s at the process temperature of 550 C.

Effect of CoSi_2 buffer layer on structure and magnetic properties of Co films grown on Si(001) substrate

Buffer layer provides an opportunity to enhance the quality of ultrathin magnetic films. In this paper, Co films with different thickness of Co Si2 buffer layers were grown on Si（001） substrates. In order to investigate morphology, structure,and magnetic properties of films, scanning tunneling microscope（STM）, low energy electron diffraction（LEED）, high resolution transmission electron microscopy（HRTEM）, and surface magneto-optical Kerr effect（SMOKE） were used. The results show that the crystal quality and magnetic anisotropies of the Co films are strongly affected by the thickness of Co Si2 buffer layers. Few Co Si2 monolayers can prevent the interdiffusion of Si substrate and Co film and enhance the Co film quality. Furthermore, the in-plane magnetic anisotropy of Co film with optimal buffer layer shows four-fold symmetry and exhibits the two-jumps of magnetization reversal process, which is the typical phenomenon in cubic（001） films.

White Organic Light-emitting Diodes with A Sr_2SiO_4:Eu^(3+) Color Conversion Layer

Abstract:Hybrid inorganic/organic white organic light emitting diodes(hybrid-WOLEDs)are fabricated by combi-ning the blue phosphorescent organic light emitting diodes(PHOLEDs)with red Sr2SiO4:Eu3+phosphor spin coatedas a color conversion layer(CCL)over the other side of glass substrate on the devices.The basic configuration of thePHOLEDs consists a host material,N,N'-dicarbazolyl-3,5-benzene(mCP)which doped with a blue phosphorescentiridium complexes iridium(Ⅲ)bis[(4,6-di-fluorophenyl)-pyridinato-N-C2'](FIrpic)to produce high efficient blueorganic light emitting diodes.The hybrid-WOLED shows maximum luminous efficiency of 22.1 cd/A,maximumpower efficiency of 11.26 lm/W,external quantum efficiency of 10.2%and CIE coordinates of(0.32,0.34).Mo-reover,the output spectra and CIE coordinates of the hybrid-WOLED have a small shift in different driving currentdensity,which demonstrate good color stability.

Suppressing Effects of Ag Wetting Layer on Surface Conduction of Er Silicide/Si(001) Nanocontacts

Current-voltage electrical characteristics of Er silicide/Si（001） nanocontacts are measured in situ in a scanning tunneling microscopy system. Introduced as a new technique to suppress surface leakage conduction on Si（001）,a silver wetting layer is evaporated onto the substrate surface kept at room temperature with Er Si2 nanoislands already existing. The effects of the silver layer on the current-voltage characteristics of nanocontacts are discussed.Our experimental results reveal that the silver layer at coverage of 0.4–0.7 monolayer can suppress effectively the current contribution from the surface conduction path. After the surface leakage path of nanocontacts is obstructed, the ideality factor and the Schottky barrier height are determined using the thermionic emission theory, about 2 and 0.5 eV, respectively. The approach adopted here could shed light on the intrinsic transport properties of metal-semiconductor nanocontacts.

A NOVEL MULTI-LAYER SPRAY DEPOSITION TECHNOLOGY

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Raman Study of Defects in SI－GaAs and Se－doped Epitaxial Layer Irradiated by 10 MeV Electrons

Raman scattering measurements on Se-doped GaAs epitaxial layers and semi-insulating (SI) GaAs irradi-ated by 10 Mev electrons have been investigated. Several defect-related features were observed. We suggestthat the 220 cm ￣-1mode is attribute to As_1 which is associated, at least in part, with EL2 and EL12 defects.For Sedoped samples, the Raman peaks at 205 and 258 cm￣-1 may be due to vibrational modes in small clus-ters of arsenic, and the 77 and 185 ￣-1modes are probably associated with disorder-activated first order Ra-man scattering.Irradiated results show that the small clusters of arsenic and disorder state are increased with in-creasing irradiation fluences. Other Raman peaks will also be discussed in this paper.

Developments of Cr-Si and Ni-Cr Single-Layer Thin-Film Resistors and a Bi-Layer Thin-Film Resistor with Adjustable Temperature Coefficient of Resistor

At first, Cr-Si (28 wt% Cr, 72 wt% Si) and Ni-Cr (80 wt% Ni, 20 wt% Cr) thin-film materials were deposited by using sputtering method at the same parameters, and their physical and electrical properties were investigated. The resistances of Cr-Si and Ni-Cr thin-film resistors decreased with the increase of deposition time (thickness) and their resistivity had no apparent variations as the deposition time increased. The temperature coefficient of resistance (TCR) of single-layer Cr-Si thin-film resistors was negative and the TCR value of single-layer Ni-Cr thin-film resistors was positive. For that, we used Cr-Si thin films as upper (or lower) layer and Ni-Cr thin films as lower (upper) layer to investigate a bi-layer thin-film structure. The deposition time of Ni-Cr thin films was fixed at 10 min and the deposition time of Cr-Si thin films was changed from 10 min to 60 min. We had found that as Cr-Si thin films were used as upper or lower layers they had similar deposition rates. We had also found that the thickness and stack method of Cr-Si thin films had large effects on the resistance and TCR values of the bi-layer thin-film resistors.

变质工艺对复合铝合金钎焊层Si的形貌及尺寸的影响

4045铝合金铸造过程中分别采用Na盐、Al-Sr中间合金、Al-P中间合金等不同的变质剂进行变质处理,检测并分析了铸造组织中的初晶Si、共晶Si以及复合铝合金钎焊层Si的形貌与尺寸。结果显示,经Al-Sr中间合金变质处理的铸造组织中没有块状初晶Si,且共晶Si为球化的短棒状。对复合铝合金钎焊层的形貌进行检测发现,经变质处理的试样中Si颗粒发生球化且呈短棒状,未发现大的块状Si颗粒;而未经变质处理的试样中有明显的呈长条状的Si颗粒,且平均最大Feret直径、平均最小Feret直径、平均颗粒面积、颗粒总面积、颗粒面积分数等较大。表明Al-Sr中间合金变质剂对高硅铝合金铸造组织中的Si相以及复合铝合金钎焊层Si颗粒的形貌与尺寸有明显改善作用。

F原子与Si表面相互作用的动力学研究

采用分子动力学方法模拟了F原子与Si表面相互作用,F原子入射能量分别为0.3,1,3,5,7和9 eV。在模拟过程中,F原子的沉积率与Si表面悬键密度有关,而Si原子的刻蚀率与表面晶格结构破坏程度有关,随着Si原子刻蚀率的增加,样品高度降低。在不同能量F原子作用下,样品Si表面形成Si-F反应层。Si-F反应层的厚度随入射能量的增加而增加,其组成成分对产物有至关重要的影响。

SiC_P/ZL109复合材料中SiC的界面行为

以常规 TEM为工具 ,研究了 Si CP/ ZL10 9复合材料中数十个 Si C颗粒及其界面 ,Si优先在 Si C表面上形核、长大 ,形成界面 Si,并形成大量 Si C/ Si界面。靠近 Si C界面的 Al基体中 ,普遍存在一层厚度小于 1μm的“亚晶铝带”,其内有大量位错。Si C与 Al、Si C与 Si之间虽然没有固定的晶体学位向关系 ,但是存在下列优先关系 :(110 3) Si C/ /(111) Al,[112 0 ]Si C/ / [110 ]Al;(110 1) Si C/ / (111) Si;[112 0 ]Si C/ / [112

渗硅制备6.5%Si硅钢表面Fe-Si过渡梯度层的特性

在KCl-NaCl-NaF-(SiO2)熔盐体系中,以含硅3%(质量分数)的硅钢为阴极,石墨为阳极,将电沉积硅和在硅钢基体上渗硅同时进行,制备了Fe-Si梯度层,并对梯度层的特性进行了分析。结果表明:梯度层中硅含量呈3种不同的变化规律,在靠近试样表面的部分,硅含量沿深度下降率较大;在梯度层中间部分,硅含量基本保持不变;在梯度层靠近基体一侧,硅含量的下降率介于前两者之间;梯度层中,以Fe3Si、FeSi、Fe5Si3和Fe构成的厚度占整个梯度层厚度的比率最大;梯度层沿基体一侧向表面的物质组成变化规律为Fe3Si+FeSi+Fe→Fe3Si+FeSi+Fe5Si3+Fe→FeSi,且各物质的量随硅含量的变化而变化;温度对梯度层中各物质含量的变化规律影响不大。

SiCp／Al-Fe-V-Si复合材料组织与性能的热稳定性

为研究SiCP/Al-Fe-V-Si复合材料的热稳定性,对多层喷射沉积技术制备的SiC颗粒增强Al-Fe-V-Si合金经过不同温度下的热稳定性实验后进行了硬度检测,并对其显微组织进行了电镜观察。结果表明:随着基体合金材料中Fe含量的提高,复合材料的组织和力学性能具有更好的高温稳定性。添加SiC颗粒后,SiC颗粒向基体中注入Si,由于基体中Si浓度的提高,减慢了合金中第二相弥散粒子的粗化和分解,与未添加SiC颗粒的合金材料相比,添加SiC颗粒复合材料的组织和力学性能具有更好的高温稳定性。

含有Al组分阶变AlGaN过渡层的Si基AlGaN／GaNHEMT

采用一个AlN缓冲层和两个Al组分阶变的AlGaN过渡层作为中间层,在76.2mm Si衬底上外延生长出1.7μm厚无裂纹AlGaN/GaN异质结材料,利用原子力显微镜、X射线衍射、Hall效应测量和CV测量等手段对材料的结构特性和电学性能进行了表征。材料表面平整光滑,晶体质量和电学性能良好,2DEG面密度为1.12×1013cm-2,迁移率为1 208cm2/(V.s)。由该材料研制的栅长为1μm的AlGaN/GaN HEMT器件,电流增益截止频率fT达到10.4GHz,这些结果表明组分阶变AlGaN过渡层技术可用于实现高性能Si基GaN HEMT。