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Free-standing silicon nanoprobes (SiNPs) are critical tools for intracellular bioelectrical signal recording, while a scalable fabrication of these tiny SiNPs with ab initio geometry designs has not been possible. In this work, we demonstrate a novel growth shaping of slim Si nanowires (SiNWs) into SiNPs with sharp tips (curvature radii

Growing high quality silicon nanowires (SiNWs) at elevated temperature on cooler polymer films seems to be contradictive but highly desirable for building high performance flexible and wearable electronics. In this work, we demonstrate a superfast (vnw > 3.5 μm·s-1) growth of high quality SiNWs on polymer/glass substrates, powered by self-selected laser at 808 nm heating of indium catalyst droplets that absorb amorphous Si layer to produce SiNWs. Because of the tiny heat capacity of the nanodroplets, the SiNW growth can be quickly heated up and frozen via rapid laser ON/OFF switching, enabling a deterministic diameter modulation in the ultralong SiNWs. Finally, prototype field effect transistors are also fabricated upon the laser-droplet-heating grown SiNWs with a high Ion/Ioff ratio of >104 and reasonable subthreshold swing of 386 mV·dec-1, opening a generic new route to integrate high-quality NW channels directly upon large area and lightweight polymer substrates for developing high-performance flexible electronics.

Complementary doping control in silicon nanowire (SiNW) channels is crucial for the construction of high-performance CMOS logics. Though planar in-plane solid–liquid–solid (IPSLS) growth, with an amorphous Si (a-Si) thin film as a precursor, has demonstrated a precise and scalable integration of orderly SiNWs, a complementary and tunable n-type doping has not been accomplished. This has been hindered by the fact that the phosphorus (P) gas dopants will react with the indium (In) catalyst droplet to form insoluble InP precipitates. Nevertheless, we herein report on an unexpected discovery that the P dopants first incorporated into the a-Si matrix can easily diffuse over the In catalyst droplets, without forming an InP compound, and thus reverse continuously the initial p-type SiNWs into an n-type channel. Uniform and efficient doping effects have been confirmed by both atomic probe tomography mapping and the transfer properties of SiNW FETs, which demonstrate a steep subthreshold swing of 105 mV dec−1, an on/off ratio of >107 and an electron mobility of 142 cm2 V−1 s−1. Finally, true CMOS inverters are successfully demonstrated based on the closely-packed SiNW channels of distinct doping polarities, indicating a new convenient and highly efficient doping routine to construct more advanced SiNW logics and sensors.

Three-dimensional (3D) construction of free-standing silicon (Si) nanohelices has been a formidable challenge for planar lithography and etching technology. We here demonstrate a convenient 3D growth and integration of Si nanohelices (SiNHs) upon bamboolike cylinders with corrugated sidewall grooves, where the indium catalyst droplets grow around the cylinders in a helical fashion, while consuming precoated amorphous Si (a-Si) thin film to produce crystalline Si nanowires on the sidewalls. At the end of each groove cycle, the droplets are enforced to linefeed/switch into the neighbor groove to continue a spiral growth of SiNHs with readily tunable diameter, pitch, aspect-ratio, and chiral/achiral symmetries. In addition, the SiNHs can be reliably released as free-standing units to serve as elastic links, supports and vibrational resonators. These results highlight the unexplored potential of high precision 3D self-assembly growth in constructing a wide range of sophisticated electromechanical, sensor, and optoelectronic functionalities.

Germanium quantum dots (GeQDs), addressed by self-aligned and epitaxial silicon nanowires (SiNWs) as electrodes, represent the most fundamental and the smallest units that can be integrated into Si optoelectronics for 1550 nm wavelength detection. In this work, individual GeQD photodetectors have been fabricated based on a low temperature self-condensation of uniform amorphous Si (a-Si)/a-Ge bilayers at 300 °C, led by rolling indium (In) droplets. Remarkably, the diameter of the GeQD nodes can be independently controlled to achieve wider GeQDs for maximizing infrared absorption with narrower SiNW electrodes to ensure a high quality Ge/Si hetero-epitaxial connection. Importantly, these hetero GeQD/SiNW photodetectors can be deployed into predesigned locations for scalable device fabrication. The photodetectors demonstrate a responsivity of 1.5 mA W−1 and a photoconductive gain exceeding 102 to the communication wavelength signals, which are related to the beneficial type-II Ge/Si alignment, gradient Ge/Si epitaxial transition and a larger QD/NW diameter ratio. These results indicate a new approach to batch-fabricate and integrate GeQDs for ultra-compact Si-compatible photodetection and imaging applications.

Owing to fascinating optical and electronic properties, graphene has attracted significant attention as an active component in energy harvesting. Steady advances have been achieved in last decade on the hybrid graphene/silicon Schottky solar cells that are based on an unconventional Schottky structured junction. In this brief review, we outlined the device physics and technical strategies devised to improve the power conversion efficiency of the hybrid graphene/silicon Schottky solar cells. The research results accumulated in the graphene/silicon prototype are expected to promote the low-cost solar cells.

Flexibility and power-to-weight (PTW) ratio are the key factors for promoting wearable or portable solar cell applications. Planar hydrogenated amorphous silicon (a-Si:H) thin films deposited directly on soft aluminum foils (AF) are usually subject to easy cracking and delamination due to the mechanical instability on AF surface. Here, an exceptionally robust three-dimensional (3D) construction of a-Si:H radial p-i-n junction solar cells on soft supermarket-available AF of 15 µm thick is reported, where the discrete and firmly standing Si nanowire (SiNW) cores, grown and rooted on the soft AF surface, frame up a 3D architecture that protects the protrusive photo-active radial junctions from the unstable a-Si/Al bottom layer. An excellent flexibility and integrity of the 3D a-Si:H radial junctions have been achieved, even under bending to radius of 5 mm. Remarkably, without any diffusion barrier protection, a power conversion efficiency of 5.6% has been recorded, with an open-circuit voltage of 0.71 V and photo-current density of 14.2 mA/cm2, leading to a high PTW ratio of > 1300 W/kg. Importantly, the overall fabrication cost can be largely slashed off, by ~46% compared to conventional a-Si:H solar cells, as the need for a bottom TCO contact/texturing layer, for a back-reflection coating and for a glass/polymer substrate are all exempted.

Geometric and compositional modulations are the principal parameters of control to tailor the band profile in germanium/silicon (Ge/Si) heteronanowires (NWs). This has been achieved mainly by alternating the feeding precursors during a uniaxial growth of Ge/Si NWs. In this work, a self-automated growth of Ge/Si hetero island-chain nanowires (hiNWs), consisting of wider c-Ge islands connected by thinner c-Si chains, has been accomplished via an indium (In) droplet-mediated transformation of uniform amorphous a-Si/a-Ge bilayer thin films. The surface-running In droplet enforces a circulative hydrodynamics in the nanoscale droplet, which can modulate the absorption depth into the amorphous bilayer and enable a single-run growth of a superlattice-like hiNWs without the need for any external manipulation. Meanwhile, the separation and accumulation of electrons and holes in the phase-modulated Ge/Si superlattice leads to a modulated surface potential profile that can be directly resolved by Kelvin probe force microscopy. This simple self-assembly growth and modulation dynamics can help to establish a powerful new concept or strategy to tailor and program the geometric and compositional profiles of more complex hetero nanowire structures, as promising building blocks to develop advanced nanoelectronics or optoelectronics.

Flexible pressure sensors are the cornerstone of electronic skins with tactile function. However, flexible pressure sensors tend to have disadvantages of slow response speed and large hysteresis, which are caused mainly by the viscoelasticity and interfacial adhesion of flexible materials. In this letter, we adopted silicon nanowire (SiNW) arrays to fabricate a pressure sensor with a piezo-capacitance when the SiNWs are bending under pressure, which avoided the viscoelasticity and interfacial adhesion accompanying with common flexible materials. The sensor recorded unprecedented low hysteresis (~2.26%) and an extremely short response time (~3 ms). With high sensitivity (up to ~8.2 kPa−1), large response capacitance, ultralow detection limit (0.1 Pa), and good repeatability and stability, the sensor holds potential applications in advanced electronic skins, especially when high-precision and high-speed sensing are required.

High power-to-weight ratio (PTWR) is an important figure-of-merit for high performance flexible/portable solar cells. Marrying advanced tandem junction design with three-dimensional (3D) Si nanowire (SiNW) framework enables a promising route to boost the PTWR. In this work, a radial tandem junction (RTJ) thin film solar cell has been demonstrated, for the first time, over SiNWs, which consist of radially deposited p-i-n multilayers with hydrogenated amorphous silicon (a-Si:H) and hydrogenated amorphous silicon germanium (a-SiGe:H) absorption layers in the outer and the inner junctions, respectively. The strong light trapping within the 3D SiNW framework allows for the use of a very thin a-SiGe:H (~45 nm) absorption layer to harvest efficiently the long wavelengths. The RTJ cells fabricated via a one-pump-down process in a single PECVD chamber, directly upon 15 µm thick aluminum foils demonstrate an excellent flexibility that can bend to 10 mm radius and achieve a record PTWR~1628 W/kg, and accomplish a high open-circuit voltage, filling factor and conversion efficiency of 1.2 V, 61.5% and 8.1% on glass, respectively, substantially improved compared to those accomplished by radial single junction cells. These results highlight the unique potential of 3D radial tandem technology to enable a new generation of high performance and durable flexible photovoltaics.

Line-shape engineering is a key strategy to endow extra stretchability to 1D silicon nanowires (SiNWs) grown with self-assembly processes. We here demonstrate a deterministic line-shape programming of in-plane SiNWs into extremely stretchable springs or arbitrary 2D patterns with the aid of indium droplets that absorb amorphous Si precursor thin film to produce ultralong c-Si NWs along programmed step edges. A reliable and faithful single run growth of c-SiNWs over turning tracks with different local curvatures has been established, while high resolution transmission electron microscopy analysis reveals a high quality monolike crystallinity in the line-shaped engineered SiNW springs. Excitingly, in situ scanning electron microscopy stretching and current-voltage characterizations also demonstrate a superelastic and robust electric transport carried by the SiNW springs even under large stretching of more than 200%. We suggest that this highly reliable line-shape programming approach holds a strong promise to extend the mature c-Si technology into the development of a new generation of high performance biofriendly and stretchable electronics.

Evolutionary process of a nanoscale FinFET channel during rapid hydrogen thermal treatment is modeled using a kinetic Monte Carlo simulation. In this paper, a novel model of nanoscale FinFET channel is proposed based on the surface diffusion theory of silicon fin structures. The evolution characteristics of fin surface morphology, including line edge roughness (LER), line width roughness, and the cross-correlation coefficient ρ, are investigated in the diffusion process of silicon fin structures at different temperatures and time. All the characteristic parameters can directly affect the carrier transport performance of FinFET. The LER of a silicon fin has been effectively reduced by at least 60%. The linewidth roughness and ρ was also investigated in the evolution of FinFET channel. The results indicate that an optimized nanoscale FinFET channel can be achieved by controlling the migration of surface silicon atoms in rapid hydrogen thermal treatment technology application, yielding atomically smooth sidewall surfaces. The present experimental results are coincided with the simulation results. Thus, such technology plays a crucial role in the application of nanoscale FinFET.

The evolution of a two-dimensional silicon surface under hydrogen thermal treatment is studied by kinetic Monte Carlo simulations, focusing on the dependence of the migration behaviors of surface atoms on both the temperature and hydrogen pressure. We adopt different activation energies to analyze the influence of hydrogen pressure on the evolution of surface morphology at high temperatures. The reduction in surface roughness is divided into two stages, both exhibiting exponential dependence on the equilibrium time. Our results indicate that a high hydrogen pressure is conducive to obtaining optimized surfaces, as a strategy in the applications of three-dimensional devices.

High mobility, scalable and even transparent thin-film transistors (TFTs) are always being pursued in the field of large area electronics. While excimer laser-beam-scanning can crystallize amorphous Si (a-Si) into high mobility poly-Si, it is limited to small areas. We here demonstrate a robust nano-droplet-scanning strategy that converts an a-Si:H thin film directly into periodic poly-Si nano-channels, with the aid of well-coordinated indium droplets. This enables the robust batch-fabrication of high performance Fin-TFTs with a high hole mobility of >100 cm2 V−1 s−1 and an excellent subthreshold swing of only 163 mV dec−1, via a low temperature

Three-dimensional (3D) construction of radial junction hydrogenated amorphous silicon (a-Si:H) thin film solar cells on standing silicon nanowires (SiNWs) is a promising strategy to maximize the light harvesting performance and improve the photocarrier collection in an optimized junction configuration. The unique light in-coupling and absorption behaviour in the antenna-like 3D photonic structures also necessitates a set of new theoretical models and simulation tools to design, predict and optimize the photovoltaic performance of radial junction solar cells, which can be rather different from planar junction solar cells. Recently, the performance of radial junction a-Si:H thin film solar cells has progressed steadily to a level comparable or even superior to that of their planar counterparts, with plenty of room for further improvement. This review will first address the growth strategy and critical parameter control of SiNWs produced via a plasma-assisted low-temperature vapour-liquid-solid procedure using low-melting-point metals as the catalyst. Then, the construction of high-performance radial junction thin film solar cells over the standing SiNW matrix, as well as their optimal structural designs, will be introduced. At the end, the new applications of 3D radial junction units will be summarized, which include, for example, the construction of very flexible, low-cost and efficient a-Si:H solar cells with the highest power-to-weight ratio, the demonstration of highly sensitive solar-blind photodetectors operating at the ultraviolet wavelength spectrum and the development of novel biomimetic radial tandem junction photodetectors with an intrinsic red-green-blue (RGB) colour distinguishing capability.

The ability to program highly modulated morphology upon silicon nanowires (SiNWs) has been fundamental to explore new phononic and electronic functionalities. We here exploit a nanoscale locomotion of metal droplets to demonstrate a large and readily controllable morphology engineering of crystalline SiNWs, from straight ones into continuous or discrete island-chains, at temperature, The ability to program periodic morphology into nanowires affords control over photonic and electronic transport properties. Here, the authors stimulate Plateau-Rayleigh transformations in silicon nanowires through an oscillating catalyst droplet, resulting in nanowires with island-chain morphology.

Solutions with large-scale dispersions of 2D black phosphorus (BP), often referred to as phosphorene, are obtained through solvent exfoliation. But, rapid phosphorene synthesis remains a challenge. Furthermore, although the chemical sensing capability of BP-based sensors has been theoretically predicted, its experimental verification remains lacking. In this study, we demonstrate the use of supercritical carbon dioxide-assisted rapid synthesis (5h) of few-layer BP. In addition, we construct a non-enzymatic hydrogen peroxide (H2O2) sensor based on few-layer BP for the first time to utilize BP degradation under ambient conditions. The proposed H2O2 sensor exhibits a considerably lower detection limit of 1 × 10(-7) M compared with the general detection limit of 1 × 10(-7) M-5 × 10(-5)M via electrochemical methods. Overall, the results of this study will not only expand the coverage of BP research but will also identify the important sensing characteristics of BP.

Guided growth of silicon nanowires (SiNWs) into precise locations, via an in-plane solid–liquid–solid (IPSLS) mechanism, is a key basis for scalable integration of SiNW-based electronics, but an effective n-type doping has not yet been accomplished. In this work, we report a bismuth (Bi) catalyzed and doped growth of IPSLS SiNWs, where the incorporation of Bi atoms gives rise to efficient n-type doping, as confirmed by electron dispersion analysis and transfer properties of SiNW transistors. Interestingly, a rich geometry evolution is observed during the Bi-catalyzed planar growth, which evolves from discrete islands to continuous island chains and to uniform segments, prior to a final droplet collapsing/flattening at the end. A growth model has been established to address this peculiar phenomenon, emphasizing the impact of surface/interface tensions on the stability of the leading catalyst droplet. These results provide a solid basis for the construction of more advanced complementary SiNW logics and electronics.

In this paper, 1D In2Te3 nanowires were synthesizes through a simple solvothermal approach. The morphology was first studied by scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). From the results, the nanowires have a diameter from 100 to 200 nm and a length of dozens of microns. X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectrum were used to study the composition, crystal structures, and optical property. Based on the typical nanowire sample, experiment factors were changed to synthsize other samples in order to study the influence factors. A possible growth mechanism of the nanowires was proposed based on a series of experimental results. This material has a broad light detection range covering the UV-visible-NIR region from the photoelectrical test, which makes it potential for applications in photodetectors and solar cells.

Wafer-scale three-dimensional (3D) surface enhancement Raman scattering (SERS) substrates were prepared using the plasma etching and ion sputtering methods that are completely compatible with well-established silicon device technologies. The substrates are highly sensitive with excellent uniformity and reproducibility, exhibiting an enhancement factor up to 10 12 with a very low relative standard deviation (RSD) around 5%. These are attributed mainly to the uniform-distributed, multiple-type high-density hot spots originating from the structural characteristics of Ag nanoparticles (NPs) decorated Si nanocone (NC) arrays. We demonstrate that the trace dimethyl phthalate (DMP) at a concentration of 10 −7 M can be well detected using this SERS substrate, showing that the AgNPs-decorated SiNC arrays can serve as efficient SERS substrates for phthalate acid esters (PAEs) detection with high sensitivity.

Background We sought to assess the expression of five cell stress molecules: Heat shock protein (HSP)-60, HSP-70, interferon (IFN)-α, rat retinoic acid early induible-1 like transcript (RRLT), and vasoactive intestinal peptide (VIP) during rat chronic small bowel allograft rejection. Methods A rat model of small bowel allograft rejection was induced on postoperative day 90 using F344 rat as donor and Lewis rat as recipient. Results We demonstrated increased expression of lamina propria HSP-60 (mean rank grade 8.3 and 3.2, respectively), graft RRLT (relative mRNA amount 5.1 ± 1.8 and 3.0 ± 1.3, respectively) and IFN-α (relative mRNA amount 108.3 ± 49.2 and 59.2 ± 22.0, respectively) in allograft group compared with the isograft group. Conclusion These data suggest the presence of cell stress during chronic small bowel allograft rejection.

The evolutionary process of nanoscale FinFET channel was investigated under hydrogen thermal treatment using kinetic Monte Carlo (KMC) simulation. We adopt appropriate activation energy to analyze the influence of hydrogen treatment temperatures and time on fin structure. Line edge roughness (LER) of silicon fin structure is effectively reduced in present KMC model. Our results indicate that optimized fin structure can be obtained by precisely adjusting migration of surface silicon atoms at high temperatures, which play a crucial role in the application of three-dimensional devices.

Black arsenic phosphorus (b-AsP) is a promising two-dimensional material for various optoelectronic applications, bridging the wavelength gap between two-dimensional molybdenum disulfide and graphene. In particular, it has intriguing potential in photodetectors and great advantages in the mid-infrared field. However, its optoelectronic modulation has yet to be elucidated, which requires a fundamental understanding of its field-effect optical modulation. Here, we report the measurements of the lower-energy infrared anisotropic optical response of thin b-AsP under different electrical gating. We reveal that in addition to band edge absorption, amplitude modulation of sub-band absorption up to ten percent is also obtained in reflection extinction. These in-gap absorptions are attributed to spin-orbital coupling and free carrier absorption. Our results suggest the important potential for use of b-AsP in mid-infrared optoelectronic modulator applications.

We have produced glycerol-bonded 3C-SiC nanocrystal (NC) films, which when excited by photons of different wavelengths, produce strong and tunable violet to blue-green (360-540 nm) emission as a result of the quantum confinement effects rendered by the 3C-SiC NCs. The emission is so intense that the emission spots are visible to the naked eyes. The light emission is very stable and even after storing in air for more than six months, no intensity degradation can be observed. X-ray photoelectron spectroscopy and absorption fine structure measurements indicate that the Si-terminated NC surfaces are completely bonded to glycerol molecules. Calculations of geometry optimization and electron structures based on the density functional theory for 3C-SiC NCs with attached glycerol molecules show that these molecules are bonded on the NCs causing strong surface structural change, while the isolated levels in the conduction band of the bare 3C-SiC NCs are replaced with quasi-continuous bands that provide continuous tunability of the emitted light by changing the frequencies of exciting laser. As an application, we demonstrate the potential of using 3C-SiC NCs to fabricate full-color emitting solid films by incorporating porous silicon.

Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs.

Silicon (Si)-based light emitting thin film has been a key ingredient for all-Si-based optoelectronics. Besides material engineering, adopting a novel 3D photonic architecture represents an effective strategy to boost light excitation and extraction from Si-based thin film material. We here explore the use of a nanowires (NW) framework, grown via vapor-liquid-solid mode, to achieve strongly enhanced yellow-green luminescence from SiN(x)O(y)/NW core-shell structure, with an order of magnitude enhancement compared to co-deposited planar references. We found that choosing geometrically-identical but different NW cores (Si or SiO(2)) can lead to profound influence on the overall light emission performance. Combining parametric investigation and theoretical modeling, we have been able to evaluate the key contributions arising from different mechanisms that include near-field enhancement, 3D light trapping and enhanced light extraction. These new findings indicate a new and effective strategy for strong Si-based thin film light emitting source, while being generic enough to be applicable in a wide variety of other thin film materials.

Gallium nitride (GaN) epilayers were grown on Si(1 1 1) substrates using nearly polycrystalline α-Al2O3 as the buffer layer by low-pressure metal organic-chemical vapor deposition. The buffer was formed by anodic porous alumina annealed at high temperature. The scanning electron microscope measurement showed that the surface of GaN epilayer was smooth. Simple photoconductive detectors were fabricated with these materials. The spectral response of these detectors exhibited a relatively sharp cutoff near the wavelength of 360 nm and a peak at 340 nm with a shoulder near 360 nm. Under 5 V bias, the responsivities at 340 and 360 nm were measured to be 3.3 and 2.4 A/W respectively.

Imitating natural rod or cone cells in human eyes can inspire a biomimetic design of filter-free color sensing photodetector with the aid of three-dimensional (3D) nanophotonic engineering. Here, a novel radial tandem junction (RTJ) super-rod structure is proposed and demonstrated, which consists of coaxially stacking hydrogenated amorphous silicon PIN junctions upon silicon nanowires, resembling to the live retinal cells in terms of both geometry and dimension. As a consequence, these RTJ units enjoy a unique wavelength-selective and cavity-mode-assisted light absorption/responses in the inner and the outer radial PIN junctions, which are readily tunable to achieve natural RGB color discrimination in the RTJ rod-cells without the need of any filter system. This unique RTJ design can indicate a new 3D implementation of color sensing photodetectors enabled by advanced nanophotonic structuring and engineering.

The radial junction (RJ) architecture has proven beneficial for the design of a new generation of high performance thin film photovoltaics. We herein carry out a comprehensive modeling of the light in-coupling, propagation and absorption profile within RJ thin film cells based on an accurate set of material properties extracted from spectroscopic ellipsometry measurements. This has enabled us to understand and evaluate the impact of varying several key parameters on the light harvesting in radially formed thin film solar cells. We found that the resonance mode absorption and antenna-like light in-coupling behavior in the RJ cell cavity can lead to a unique absorption distribution in the absorber that is very different from the situation expected in a planar thin film cell and that has to be taken into account in the design of high performance RJ thin film solar cells. When compared to the experimental EQE response of real RJ solar cells, this modeling also provides an insightful and powerful tool to resolve the wavelength-dependent contributions arising from individual RJ units and/or from strong light trapping due to the presence of the RJ cell array.

Hydrogenated microcrystalline silicon films without an amorphous incubation layer were deposited on glass substrates at a high rate and a low temperature by a jet-type inductively coupled plasma chemical vapor deposition technique. It was observed that the amorphous incubation layer present at the initial stage of the deposition gradually crystallized during the growth process, and an almost completely crystallized layer was obtained. It is believed that abundant hydrogen atoms with sufficient energy diffuse into the incubation layer and subsequently annealing through a hydrogen mediated chemical reaction to induce the structural evolution of the incubation layer.

Er:Si/Al2O3 superlattices are fabricated by pulsed laser deposition (PLD) technique. Photoluminescence (PL) and PL excitation spectra measurements are carried out. The annealing temperature dependent PL intensity curves are presented. The influence of Si crystallization on the Er ions luminescence shows that the thinner the Si layer, and the shorter the distance r, the better its sensitizing performance.

Amorphous Ge-rich Si1−xGex films with local Ge-clustering were deposited by dual-source jet-type inductively coupled plasma chemical-vapor deposition (jet-ICPCVD). The structural evolution of the deposited films annealed at various temperatures (Ta) is investigated. Experimental results indicate that the crystallization occurs to form Ge and Si clusters as Ta = 500 °C. With raising Ta up to 900 °C, Ge clusters percolate together and Si diffuses and redistributes to form a Ge/SiGe core/shell structure, and some Ge atoms partially diffuse to the surface as a result of segregation. The present work will be helpful in understanding the structural evolution process of a hybrid SiGe films and beneficial for further optimizing the microstructure and properties.

Understanding the p-n junctions is of great importance because p-n junctions are the essential elements of semiconductor devices. In this study, we experimentally investigated the strain induced electrical properties modulation of Si p+-n and n+-p junctions. It is found that, under the uniaxial tensile stress, the current in the large-forward-bias region increases significantly, while a rather small current increase is observed in the diffusion-current-dominant region. Besides, the ideality factors in the diffusion-current-dominant region and the large-forward-bias region decrease when the amount of the applied stress increases. The observations are explained by the strain induced variations in energy band structure, their effect on minority carrier concentrations, and the piezoresistance effect.

We report here a strong and stable electroluminescence (EL) from Si-rich hydrogenated polymorphous silicon carbon thin films (pm-Si1-xCx : H) fabricated in a plasma-enhanced chemical vapor deposition system. We investigate an unusual forming process in the pm-Si1-xCx : H thin films, during initial EL stressing, and propose a current-stress-induced phase separation process for the formation of new Si nanoclusters, which give rise to strongly enhanced emissions in both visible and near infrared ranges at 1.8–2.1 eV and 0.8–1.2 eV, respectively. The sub-crystalline-Si-bandgap emission is particularly attractive to realize a Si-based multi-band light source for optical interconnection and telecommunication.

The transport behaviors of La0.5Ca0.5MnO3/LaMnO3/SrTiO3:Nb heterojunctions with a LaMnO3 layer thickness of between 0 and 12 nm have been systematically studied. The effect of the magnetic field on the junction without the buffer layer is weak. The influence of the magnetic field on the junction is maximized when the layer thickness is ∼3 nm, demonstrated by a significant field-induced increase in current when the bias voltage is fixed. The corresponding magnetoresistance of the junction is negative, and its maximal value is ∼−32% for a field change of 5 T at 80 K. Based on a quantitative analysis of the current-voltage characteristics, the interfacial barrier can be derived, and it shows a complex variation with an increase in layer thickness, first decreasing and then increasing. This is the apparent reason for the change in buffer-layer-enhanced negative magnetoresistance of the junctions for different layer thicknesses.

Microstructures of phosphorus-doped hydrogenated microcrystalline silicon (μc-Si:H) thin films deposited by plasma-enhanced chemical vapor deposition are certainly dependent on the thickness of the H2 plasma-treated amorphous silicon (a-Si:H) layers. An ultrathin H-treated a-Si:H layer is beneficial in obtaining a very thin μc-Si:H film with high conductivity. Experimental results indicate that H2 plasma treatment induces the occurrence of high-pressure H2 in microvoids and causes compressive stress inside the ultrathin a-Si:H layers, thereby enhancing the generation of strained Si–Si bonds and nucleation sites and consequently accelerating the nucleation of μc-Si:H films.

Here, we investigate the enhanced tunable photoluminescence (PL) of hydrogenated polymorphous silicon carbon (pm-Si1−xCx:H) thin films fabricated in a plasma enhanced chemical vapor deposition system. The silicon nanocrystal (nc-Si) inclusions are formed during gas-phase nucleation and incorporated in the hydrogenated amorphous silicon carbon (a-SiC:H) matrix. The nc-Si provides high-quality recombination centers for the photogenerated carriers in the pm-Si1−xCx:H material, while the a-SiC:H matrix plays a role of sensitizer. We elucidate and provide experimental evidence for this excitation-transfer mechanism. Strongly enhanced PL performance can be achieved by effective matrix passivation that favors a diffusion-driven carrier recombination in the nc-Si centers.

Microcrystalline silicon films without an amorphous incubation layer were deposited onto glass substrates at a high rate and a low temperature by a jet-type inductively coupled plasma chemical vapor deposition (jet-ICPCVD) technique. It was observed that the amorphous incubation layer present at the beginning of the deposition gradually crystallized during the growth process, and an almost completely crystallized layer was obtained. The analysis indicates that high density plasma, spatial plasma potential, and high pressure are of substantive benefit to the generation of abundant energetic hydrogen atoms, which diffuse into the incubation layer and control the crystallization through a hydrogen-mediated chemical reaction.

In this letter, we report on the characteristics of 1.54μm photoluminescence emission of Er-doped HfO2 films synthesized by pulsed laser deposition and ion implantation. An efficient emission at 1.54μm in the annealed HfO2 films has been observed under a broad band excitation from 400nm to a higher energy at room temperature. X-ray diffraction and electron paramagnetic resonant measurements were used to analyze the correlation between the optical properties and microstructures. An energy transfer mechanism is proposed that the O vacancy in the bulk acts as an effective sensitizer for the neighboring Er ions and greatly enhances the 1.54μm band emission. These results lay an important basis for the future silicon-based integrated optoelectronic device applications of Er-doped HfO2 films.