SiO2 Layer Research Articles

Enhancement of Interlayer Exciton Emission in a TMDC Heterostructure via a Multi-Resonant Chirped Microresonator Upto Room Temperature.

We report on multi-resonance chirped distributed Bragg reflector (DBR) microcavities. These systems are employed to investigate the light-mater interaction with both intra- and inter-layer excitons of transition metal dichalcogenide (TMDC) bilayer heterostructures. The chirped DBRs consisting of SiO2 and Si3N4 layers of gradually varying thickness exhibit a broad stopband with a width exceeding 600nm. Importantly, the structures provide multiple resonances across a broad spectral range, which can be matched to resonances of the embedded TMDC heterostructures. Studying cavity-coupled emission of both intra- and inter-layer excitons from an integrated WSe2/MoSe2 heterostructure in a chirped microcavity system, an enhanced interlayer exciton emission with a Purcell factor of 6.67 ± 1.02 at 4 K is observed. The cavity-enhanced emission of the interlayer exciton is used to investigate its temperature-dependent luminescence lifetime of 60ps at room temperature. The cavity system modestly suppresses intralayer exciton emission by intentional detuning, thereby promoting a higher IX population and enhancing cavity-coupled interlayer exciton emission. This approach provides an intriguing platform for future studies of energetically distant and confined excitons in different semiconducting materials, which paves the way for various applications such as microlasers and single-photon sources by enabling precise emission control and utilizing multimode resonance light-matter interaction.

Effect of SiO2 Layer Thickness on SiO2/Si3N4 Multilayered Thin Films

Silicon nitride (Si3N4) materials are widely used in the electronics, optoelectronics, and semiconductor industries, with Si3N4 thin films exhibiting high densities, high dielectric constants, good insulation performance, and good thermal and chemical stability. However, direct deposition of Si3N4 thin films on glass can result in considerable tensile stress and cracking. In this study, magnetron sputtering was used to deposit a Si3N4 thin film on glass, and a silicon dioxide (SiO2) thin film was introduced to reduce the Si3N4 binding force and stress. The effect of the SiO2 layer thickness on the SiO2/Si3N4 multilayered thin film was explored. The results indicated that the introduction of the SiO2 layer could improve the weak adhesion characteristics of Si3N4 thin films. Moreover, sputtering the SiO2 layer to 150 nm resulted in the highest hardness and transmittance of the SiO2/Si3N4 multilayered thin films. The findings of this study lay a solid foundation for the application of Si3N4 thin films on glass.

Insight into the configuration of hard-soft carbon composites for high performance sodium-ion batteries

Hard carbon materials are considered suitable anode materials for sodium-ion batteries due to their abundant defect sites and large interlayer distance, which are respectively beneficial to the adsorption/desorption and insertion/extraction behaviors of Na+ during the electrochemical process. However, the poor electrical conductivity resulting from the intrinsic short-range ordered structure in the carbon skeleton and limited active sites significantly hinders their electrochemical performance. Herein, hard and soft carbon composites with various configurations are developed using a layer-by-layer coating method with SiO2 nanospheres as templates. These composites, including the hard carbon coated soft carbon composite structure (SC@HC), soft carbon coated hard carbon composite structure (HC@SC), and uniformly mixed soft and hard carbon composites (HSC), are prepared through confined-carbonization under the outermost SiO2 layer. The resulting hollow nanospheres possess ultra-small diameters (approximately 50 nm), ultra-thin wall thicknesses (5-6 nm), and different hard/soft carbon layer arrangements. Evaluation of sodium storage properties showed that the combination of soft and hard carbon outperformed pure soft or hard carbon, with HC@SC configuration offering materials with larger interlayer spacing, higher defect concentration, and a more complete conductive network. This enhances sodium storage capacity (293 mAh g-1@1 A g-1) and rate performance (242 mAh g-1@5 A g-1). The findings of this study present a novel approach to designing soft and hard carbon composites for high-performance sodium-ion batteries.

Magnetic contrast layers with functional SiO2 coatings for soft-matter studies with polarized neutron reflectometry

This study introduces silicon substrates with a switchable magnetic contrast layer (MCL) for polarized neutron reflectometry (PNR) experiments at the solid–liquid interface to study soft-matter surface layers. During standard neutron reflectometry (NR) experiments on soft-matter samples, structural and compositional information is obtained by collecting experimental data with different isotopic contrasts on the same sample. This approach is normally referred to as contrast matching, and it can be achieved by using solvents with different isotopic contrast, e.g. different H2O/D2O ratios, and/or by selective deuteration of the molecules. However, some soft-matter systems might be perturbed by this approach, or it might be difficult to implement, particularly in the case of biological samples. In these scenarios, solid substrates with an MCL are an appealing alternative, as the magnetic contrast with the substrate can be used for partial recovery of information on the sample structure. More specifically, in this study, a magnetically soft Fe layer coated with SiO2 was produced by ion-beam sputter deposition on silicon substrates of different sizes. The structure was evaluated using X-ray reflectometry, atomic force microscopy, vibrating sample magnetometry and PNR. The collected data showed the high quality and repeatability of the MCL parameters, regardless of the substrate size or the thickness of the capping SiO2 layer. Previously proposed substrates with an iron MCL used an Au capping layer. The SiO2 capping layer proposed here allows reproduction of the typical surface of a standard silicon substrate used for NR experiments and is compatible with a large variety of soft-matter samples. This application is demonstrated with ready-to-use 50 × 50 × 10 mm substrates in PNR experiments for the characterization of a lipid bilayer in a single solvent contrast. Overall, the article highlights the potential of PNR with an MCL for the investigation of soft-matter samples.

Intrinsic doping and ageing of indium oxide thin films

Indium oxide (In2O3) is one of the most used materials for the synthesis of transparent electronics devices and currently tin-doped indium oxide (ITO) dominates the field of Transparent Conductive Oxides for most applications, from ICT to photovoltaics. In this work we present a study on the responses of indium oxide upon the formation, and stabilization, of point defects induced with different methods. After the deposition of In2O3 thin films via RF magnetron sputtering, treatments such as Ion Implantation (I.I.), Ultraviolet (UV) irradiation and Sun exposure were employed to generate oxygen vacancies as intrinsic dopants. Both I.I. and UV irradiations significantly improved the electrical conductivity of films, increasing the carrier density by up to 3 orders of magnitude. Moreover, after I.I. also the crystalline quality of the films was enhanced.To monitor the stability of oxygen vacancies upon exposure to ambient atmosphere, the ageing of samples was followed and recorded for a couple of weeks, reporting a fast and strong degradation of electrical properties. As a facile strategy to counteract the sheet resistance increase, samples were encapsulated in an ultra-thin (≈10 nm) SiO2 layer deposited via sputtering. Irradiated and encapsulated films retained a much lower sheet resistance throughout the observation time, preserving the samples conductivity.

Low-frequency capacitor with hopping electrical conductivity of the working substance (on the example of a-Si:H)

We propose a structural and electrical schemes of a capacitor based on a 3 μm thick a-Si:H (amorphous hydrogenated silicon) layer separated from the metal plates by 0.3 μm thick dielectric layers of SiO2 (silicon dioxide). We consider room temperatures (T ≈ 300 K) when in the absence of illumination for a-Si:H the hopping mechanism of electron migration via point defects of the structure prevails. For such a capacitor, the dependencies of the capacitance on the frequency of the measuring signal ω/2π in the range from 0.1 to 300 Hz are calculated for the a-Si:H layer with stationary hopping electrical conductivity σdc ≈ 1 ∙ 10−10 (Ohm ∙ cm)−1. It is assumed that there is no end-to-end electron transfer between the a-Si:H layer, dielectric layers and capacitor plates in the small-signal mode of capacitance measurement. It is shown that the real part of the capacitance of the capacitor decreases with increasing angular frequency ω, and the imaginary part is negative and depends non-monotonically on ω. The decrease in the real part of the device capacitance to the geometric capacitance of the series-connected oxide layers and the a-Si:H layer with increasing ω is due to a decrease in the electrical resistance of the capacitor. As a result, with increasing ω, the imaginary part of the capacitance is shunted by the hopping electrical conductivity of the capacitor. The phase shift for a sinusoidal electrical signal supplied to the capacitor is determined depending on the frequency ω/2π in the range of 0.1–300 Hz for the values of electrical conductivities of the hydrogenated amorphous silicon layer σdc ≈ 1 ∙ 10−11, 1 ∙ 10−10, and 1 ∙ 10−9 (Ohm ∙ cm)−1 at the temperature 300 K. With an increase in the electrical conductivity σdc of the a-Si:H layer, the minimum absolute value of the phase shift angle (≈65°) shifts to the high- frequency region (from 1 to 100 Hz). The proposed low-frequency capacitor can find application in electrical circuits for detecting low-frequency electrical signals for the purposes of biomedicine.

In-situ synthesis of SiC/SiO2 nanowires by catalyst-free thermal evaporation of silicon powder and their photoluminescence properties

Core-shell structured SiC/SiO2 nanowires (SiC/SiO2 NWs) were synthesized by a simple thermal evaporation method without a catalyst. The influence of the growth temperature and holding time on the microstructure and composition of the nanowires were investigated. The results indicate that within the temperature range of 1150 to 1550 °C, the color of SiC/SiO2 nanowires gradually transitions from pure white to off-white with increasing temperature. During this process, the average diameter of SiC/SiO2 increases from ∼74 nm to ∼291 nm, while the surface SiO2 layer thickness decreases from ∼17 nm to ∼5 nm, with nanowires can reach lengths of hundreds of micrometres. Variations in supersaturation of SiO and CO at different temperatures lead to discrepancies in nanowire diameter and SiO2 shell thickness. At 1350 °C, prolonged holding time enhances silicon powder reaction, resulting in increased structural disorder of the obtained SiC/SiO2 nanowires. The nanowire growth follows a vapor-solid (VS) mechanism. Additionally, the study demonstrates that the photoluminescence (PL) characteristics of the nanowires exhibit a blue shift attributable to their nanoscale dimensions, while variations in emission spectra correlate with stacking faults, SiC diameter, and SiO2 thickness. This work may be provide a theoretical basis for preparing SiC/SiO2 nanowires with different diameters and SiO2 shell thicknesses, which is crucial for advancing the development and application of SiC/SiO2 nanoceramics.

Laser ablation behavior and mechanisms of 3D carbon fiber reinforced ZrB2-SiC composite

The high-performance 3D Cf-PyC/ZrB2-SiC composite was fabricated by vibration-assisted slurry impregnation and low-temperature hot pressing. The composite exhibited superior laser ablation resistance, leading to a low linear loss rate of 1.56×10−2 mm/s at laser power density of 4878 W/cm2 (Power 300 W, Laser beam diameter 2.8 mm) for 90 s. The coupling effect of a dense SiO2 layer in fringe region followed by dense ZrO2 layer in transitional region and next porous ZrO2 layer in center region achieved superior laser ablation resistance.

The oxidation behavior and corrosion mechanism of SiC matrix ceramics in a high temperature wet air environment

The oxidation behavior and corrosion mechanism of SiC ceramics were investigated at high temperatures ranging from 1000 ℃ to 1200 ℃ in wet environments (75 % water/25 % air). The results demonstrate the formation of protective SiO2 layers, which effectively inhibit further oxidation at 1000 ℃ and 1100 ℃. However, simultaneous oxidation and water vapor corrosion occur at 1200 ℃, leading to substantial weight loss and the development of numerous porous layers that can reach up to 30 μm after 10 h oxidation. The YAG phases in the SiC ceramics react with SiO2 to generate Y2Si2O7, Y2SiO5, and/or Al2Si2O7 phases during oxidation process, which exhibit enhanced corrosion resistance under wet environments.

MEMS reconfigurable terahertz meta-absorber with polarization-dependent and sensing characteristics

This study presents and demonstrates a design of a micro-electro-mechanical system (MEMS) reconfigurable terahertz (THz) metamaterial absorber (TMA) that shows tunable free spectra range with a maximum value as 166 GHz in transverse magnetic mode and switchable resonance from 1.24 THz to 1.53 THz. The unit structure of TMA consists of two movable rectangular resonators aside and an x-shaped resonator at the center comprising two c-shaped resonators connected upside down. The material configuration of TMA is typical of the metal–insulator-metal sandwich configuration. That is a bottom Au layer preventing the penetration of the THz wave, a dielectric SiO2 layer to accommodate and absorb the incident wave, and a patterned Au structure array to select the resonant frequency. The electromagnetic response of TMA could be flexibly modulated when the structure is reconfigured by changing the gaps between x-shaped resonators and rectangular resonators based on the MEMS platform. Meanwhile, owing to the asymmetry of resonant structure, the electromagnetic response of TMA could be tuned from single-, dual-, triple- quad-resonances by varying the polarization state of incidence. Furthermore, the sensitivity of TMA is explored and demonstrated with remarkable linearity under a variation of the surrounding environment refractive index from 1.0 to 2.0. The feasibility of TMA is validated as the experimental absorption spectra are well meet the simulation results. The above results indicate the proposed TMA possesses great potential applications in multiple resonance switches, polarization switches, and highly efficient environmental sensors.

The static corrosion behaviors of gelcasted MAX phases in contaminated lead-bismuth eutectic (LBE) at 600 °C with low oxygen

The deployment of gelcasted MAX phase ceramic components in nuclear reactors is critical due to their exceptional performance. This study explores the corrosion behaviors of three gelcasted MAX phase ceramics (Ti3AlC2, Ti2AlC, and Ti3SiC2) in liquid lead-bismuth eutectic (LBE) at 600 °C under low oxygen conditions. Unique corrosion layers formed on the samples: Ti₃AlC₂ developed an Al2O3 inner layer and TiO2 outer layer, Ti₂AlC showed TiO2 grains coated with FeCr2O4 spinel, and Ti3SiC2 exhibited a composite layer of TiO2, Fe3O4, SiO2, PbO, and TiO2. LBE caused slight matrix enrichment in Ti₃AlC₂ and Ti₂AlC samples. Corrosion resistance was ranked as Ti3SiC2 > Ti3AlC2 > Ti₂AlC. Additionally, a coupled corrosion phenomenon resembling electrolytic electrodeposition between MAX phase ceramics and stainless steel was observed in contaminated LBE. This research provides novel insights into the corrosion mechanisms of MAX phases, paving the way for their application in advanced nuclear systems.

SYNTHESIS AND STUDY OF OPTICAL, ELECTRICAL PROPERTIES OF TIN DIOXIDE NANOWIRES IN A SiO<sub>2</sub>/Si TRACK TEMPLATE

This work presents a study of the structural, optical and electrical characteristics of tin dioxide (SnO2) nanowires obtained by chemical deposition (CD) into a SiO2/Si track template (template synthesis). Latent tracks in the SiO2 layer were created by irradiation with swift heavy ions (SHI) of Xe at an energy of 200 MeV with a fluence of Ф = 108 cm−2 and subsequent etching in a 4% aqueous solution of hydrofluoric acid (HF). The chosen CD method is widely used for the deposition of semiconductor oxide nanowires in SiO2 nanopores. The CD method is cost-effective because it does not require special equipment for deposition of nanowires. To carry out deposition, a solution of a coordination compound of a metal and a reducing agent is used. To analyze the filling of pores after the CD process, the surface morphology of the samples was studied using a Zeiss Crossbeam 540 scanning microscope. The crystallographic structure of SnO2/SiO2/Si nanostructures with SnO2 nanopore filling was studied by X-ray diffraction. X-ray diffraction analysis (XRD) is carried out on a Rigaku SmartLab X-ray diffractometer. As a result, a SnO2-NW/SiO2/Si nanoheterostructure with an orthorhombic crystal structure of SnO2 nanowires was obtained. Photoluminescence (PL) spectra were measured upon excitation with light at a wavelength of 240 nm using a CM2203 spectrofluorimeter (Solar). Gaussian decomposition of the photoluminescence spectrum of SnO2-NW/SiO2/Si structures showed that they have low intensity, which is mainly due to the presence of defects such as oxygen vacancies, interstitial tin or tin with damaged bonds. Electrical characterization studies were performed using a VersaStat 3 potentiostat (Ametek). Measurement of the current-voltage characteristic showed that the resulting SnO2-NW/SiO2/Si nanoheterostructure contains arrays of p-n junctions.

Investigation of scale formation and degeneration of silicide coating on Nb–Si based alloy in the temperature range from 1250 °C to 1560 °C

Nb silicide coatings modified with active elements have good oxidation resistance, but there is a lack of systematic research on their oxidation behavior at high temperatures above 1250 °C. The aim of this work is to investigate the oxidation behavior of an Al–Y modified silicide coating on Nb–Si based alloy in the temperature range from 1250 °C to 1560 °C. After oxidation at 1250 °C, the scale displays a typical layered structure consisting mainly of a TiO2 outer layer, an amorphous SiO2 matrix layer embedded with TiO2 and ZrSiO4, and an inner layer consisting of SiO2 and Cr2O3. Above 1350 °C, the evaporation reaction of Cr2O3 into CrO3 (g) is significantly accelerated and Cr2O3 disappeared gradually with temperature or time. The TiO2 layers covering on the scales formed at 1250–1500 °C grow along the crystallographic orientation of [100]. The micropores formed on the surface of TiO2 should be attributed to the further oxidation of Cr2O3 into volatile oxide CrO3 (g). The scales exhibit a similar structure consisting mainly of a SiO2 glass matrix embedded with ZrSiO4 and a surface TiO2 layer until 1500 °C. Above the eutectic temperature of SiO2–TiO2 system, the scale is mainly composed of a matrix layer of SiO2–TiO2 eutectic embedded with block TiO2 particles, and a thin SiO2 interface layer at 1560 °C. The degeneration path of the (Nb,X)Si2 coating is (Nb,X)Si2 → (Ti,Nb)5Si4 → γ-(Nb,X)5Si3.

Ultrathin Graphite‐Based Full‐Color Electrochromic Devices

AbstractUltrathin graphite‐based materials have revolutionized optoelectronics through their multispectral and energy‐efficient tunability. However, their narrow color range poses a challenge in applications requiring a broad spectrum of colors for effective information delivery or aesthetic enhancement. Here, full‐color tunability is achieved in ultrathin graphite‐based electrochromic devices using Fabry‐Perot (F‐P) nanocavities. By adjusting the optical properties (n, k) of ultrathin graphite through lithium‐ion intercalation/de‐intercalation and the thickness of the dielectronic SiO2 layer, managed to control the optical reflectivity in the visible spectrum. Moreover, this prototype device consumes only 1.59 mW cm−2, just one‐tenth of the commercial organic light‐emitting displays’ energy usage. Furthermore, the pixel size in the Fabry‐Perot nanocavity‐type electrodes can be reduced to 2 µm, under half that of contemporary displays like Micro‐LED. These results pave the way for full‐color displays with minimal energy consumption and inspire extensive research in low‐power photonics.

Effect of SiO2 passivation layer on nanoporous Si photocathode under the density of SiO2 passivation layer

This study presents the fabrication and comparative evaluation of SiO2/Si photoelectrodes employing two distinct SiO2 oxidation methods. Each SiO2/Si photoelectrodes was successfully generated based on uniform SiO2 layers a top nanoporous Si that have thicknesses of 2.7 nm via hydrogen peroxide oxidation (H2O2 oxidation) and 1.8 nm via nitric acid oxidation of Si (NAOS). Notably, the thin NAOS-formed SiO2 layer resulted in a measured suboxide density approximately 4.8 times lower (0.5192 × 1014 atoms/cm2) than that of the H2O2 oxidation (2.4969 × 1014 atoms/cm2). The presence of this SiO2 layer not only passivates defects but also improves electrical properties. As a result, the photocurrent density of the NAOS-formed SiO2/Si photoelectrode notably outperformed that of the H2O2-formed counterpart (about 1.7 times). This enhancement is attributed to the consistent passivation effects and improved electrical properties achieved due to NAOS-formed SiO2. This study contributes to a deeper understanding of how the SiO2 passivation layer can be utilized to improved photocurrent density.

Reduced subthreshold swing in a vertical tunnel FET using a low-work-function live metal strip and a low-k material at the drain.

In this research paper, a vertical tunnel field-effect transistor (TFET) structure containing a live metal strip and a material with low dielectric constant is designed, and its performance metrics are analyzed in detail. Low-k SiO2 is incorporated in the channel-drain region. A live molybdenum metal strip with low work function is placed in a high-k HfO2 layer in the source-channel region. The device is examined by the parameters I off, subthreshold swing, threshold voltage, and I on/I off ratio. The introduction of a live metal strip in the dielectric layer closer to the source-channel interface results in a minimum subthreshold slope and a good I on/I off ratio. The low-k material at the drain reduces the gate-to-drain capacitance. Both the SiO2 layer and the live metal strip show excellent leakage current reduction to 1.4 × 10-17 A/μm. The design provides a subthreshold swing of 5 mV/decade, which is an excellent improvement in TFETs, an on-current of 1.00 × 10-5 A/μm, an I on/I off ratio of 7.14 × 1011, and a threshold voltage of 0.28 V.

"Core/Shell" Nanocomposites as Photocatalysts for the Degradation of the Water Pollutants Malachite Green and Rhodamine B.

"Core/shell" composites are based on a ferrite core coated by two layers with different properties, one of them is an isolator, SiO2, and the other is a semiconductor, TiO2. These composites are attracting interest because of their structure, photocatalytic activity, and magnetic properties. Nanocomposites of the "core/shell" МFe2O4/SiO2/TiO2 (М = Zn(II), Co(II)) type are synthesized with a core of MFe2O4 produced by two different methods, namely the sol-gel method (SG) using propylene oxide as a gelling agent and the hydrothermal method (HT). SiO2 and TiO2 layer coating is performed by means of tetraethylorthosilicate, TEOS, Ti(IV) tetrabutoxide, and Ti(OBu)4, respectively. A combination of different experimental techniques is required to prove the structure and phase composition, such as XRD, UV-Vis, TEM with EDS, photoluminescence, and XPS. By Rietveld analysis of the XRD data unit cell parameters, the crystallite size and weight fraction of the polymorphs anatase and rutile of the shell TiO2 and of the ferrite core are determined. The magnetic properties of the samples, and their activity for the photodegradation of the synthetic industrial dyes Malachite Green and Rhodamine B are measured in model water solutions under UV light irradiation and simulated solar irradiation. The influence of the water matrix on the photocatalytic activity is determined using artificial seawater in addition to ultrapure water. The rate constants of the photocatalytic process are obtained along with the reaction mechanism, established using radical scavengers where the role of the radicals is elucidated.

Preparation and Characterization of Silica-Coated Sodium Alginate Hydrogel Beads and the Delivery of Curcumin

In this study, to address the defects of sodium alginate (SA), such as its susceptibility to disintegration, silica was coated on the outer layer of sodium alginate hydrogel beads in order to improve its swelling and slow-release properties. Tetraethyl orthosilicate (TEOS) was used as the hydrolyzed precursor, and the solution of silica precursor was prepared by sol-gel reaction under acidic conditions. Then SA–silica hydrogel beads prepared by ionic crosslinking method were immersed into the SiO2 precursor solution to prepare SA–silica hydrogel beads. The chemical structure and morphology of the hydrogel beads were characterized by XRD, FTIR, and SEM, and the results showed that the surface of SA–silica beads was successfully encapsulated with the outer layer of SiO2, and the surface was smooth and dense. The swelling experiments showed that the swelling performance effectively decreased with the increase of TEOS molar concentration, and the maximum swelling ratio of the hydrogel beads decreased from 41.07 to 14.3, and the time to reach the maximum swelling ratio was prolonged from 4 h to 8 h. The sustained-release experiments showed that the SA–silica hydrogel beads possessed a good pH sensitivity, and the time of sustained-release was significantly prolonged in vitro. Hemolysis and cytotoxicity experiments showed that the SA-silica hydrogel beads were biocompatible when the TEOS molar concentration was lower than 0.375 M. The SA–silica-2 hydrogel beads had good biocompatibility, swelling properties, and slow-release properties at the same time.

Low-oxygen silicon preparation using vacuum treatment by oxidation control and moisture removal kinetics investigation

Diamond wire saw silicon powder (DWSSP) is a waste produced during silicon wafer processing for photovoltaic (PV) modules, and it shows significant reutilization potential. However, the presence of moisture leads to silicon oxidation and the formation of a surface SiO2 layer that hinders the recovery of high-purity silicon. In this study, vacuum treatment (VT) was used to prepare low-oxygen silicon by controlling the oxidation and removing moisture from DWSSP waste, thus preventing SiO2 layer formation. The oxygen content in DWSSP decreased by 15.01 %, from 7.26 % to 6.17 %, and the SiO2 layer thickness also decreased by 10.29 %, from 2.04 nm to 1.83 nm after the VT process. Additionally, the VT process lowered the moisture boiling point, facilitating surface evaporation and internal diffusion of moisture. This increased the moisture effective diffusion coefficient from 5.16 × 10−10–6.16 × 10−9 m2 s−1 to 1.21 × 10−9–6.88 × 10−9 m2 s−1 and reduced the apparent activation energy from 32.17 kJ mol−1 to 16.05 kJ mol−1. The efficient moisture removal of VT inhibited the growth of the SiO2 layer to enable the preparation of low-oxygen silicon during silicon recovery.

Performance improvement of planar silicon nanowire field effect transistors via catalyst atom doping control

Catalytic growth of silicon nanowires (SiNWs), mediated by metallic droplet, provide ideal quasi-1D channels to construct high performance field effect transistor (FET). However, the incorporation of catalytic metal atoms into SiNWs channels has significant impact on the FET characteristics, and thus needs to be better understood and controlled to fulfil its potential for high performance electronics. In this work, we focus on the effect of the incorporation of indium (In) catalytic atoms into planar SiNWs, grown via an in-plane solid-liquid-solid (IPSLS) mechanism, on the FET device performance. It is found that the initial high concentration of p-type In dopants in the as-grown SiNWs led to an equivalent boron (B) doping of 5×1018 cm−3. However, a simple step-wise annealing in oxygen at different temperatures, varied from 620 °C to 920 °C, can help to out-diffuse the dissolved In atoms into the surface SiO2 layer, and reduce the In concentrations down to <5×1017 cm−3, as verified by atom-probe tomography (APT) and four-point-probe measurements. This effective dopant control enables a remarkable device performance improvement of the Schottky barrier FETs, built upon an orderly array of parallel SiNWs of approximately 25 nm in diameter, where the current ratio (Ion/Ioff) has been substantially boosted from 105 to 108, while the subthreshold swing (SS) reduced from 400 mV/dec down to ∼100 mV/dec, with a hole carrier mobility increased from 10 to ∼75 cm2 V−1 s−1 as extracted according to a finite element analysis. These results pave the way for the employment of the catalytic IPSLS SiNWs to serve as high quality 1D channels for high-performance SiNWs-based electronics and sensors.