Search

An analytical device physics model is presented for determining the energy conversion efficiency of semiconductor nanowire array-based radial (core–shell) p-i-n junction betavoltaic cells for two- and three-dimensional radioisotope source geometries. Optimum short-circuit current density J sc , open-circuit voltage V oc , fill factor F F , and energy conversion efficiency η are determined for various nanowire properties, including dopant concentration, nanowire length, core diameter, and shell thickness, for Si, GaAs, and GaP material systems. A maximum efficiency of 8.05 % was obtained for GaP nanowires with diameter 200 nm (p-core diameter, i-shell, and n-shell thicknesses of 24, 29.4, and 58.6 nm, respectively), length 10 μ m , acceptor and donor concentrations of 10 19 and 5 × 10 18 cm − 3 , respectively, and a 3D source geometry. [ABSTRACT FROM AUTHOR]

This work investigates exciton localization and dynamics in semiconductor GaNAsP nanowires (NWs) with varying nitrogen concentrations. Through detailed time-resolved photoluminescence studies, we identify a nitrogen composition-dependent difference in exciton transfer between localized states formed due to alloy disorder. With [N] = 0.1%, the localized states exhibit cluster-like, non-interacting behavior, whereas at [N] = 1.1%, a continuous band of localized states is observed. Additionally, the phosphorous incorporation in the NWs appears to enhance the exciton spatial confinement compared to behaviors observed in phosphorous-free GaNAs NWs, emphasizing the role of the alloy composition in the nature of exciton localization. Temperature is highlighted as a significant factor affecting exciton mobility, enabling efficient transfer between the localized states at higher temperatures. This, in turn, influences exciton lifetimes. Our findings, therefore, shed light on the nature of exciton dynamics in GaNAsP NWs, enriching our understanding of these materials and paving the way for their applications in optoelectronics. [ABSTRACT FROM AUTHOR]

We investigate microlenses that selectively focus the light on only a small fraction of all nanowires within an arrayed InP nanowire solar cell. The nano-concentration improves both the short-circuit current (J s c ) and the open-circuit voltage (V o c ) of the solar cell. For this purpose, polymethyl methacrylate microlenses with 6 μm diameter were randomly positioned on top of an arrayed nanowire solar cell with 500 nm pitch. The microlenses were fabricated by first patterning cylindrical micropillars, which were subsequently shaped as lenses by using a thermal reflow process. The quality of the microlenses was experimentally assessed by Fourier microscopy showing strong collimation of the emitted photoluminescence. By analyzing the slope of the integrated photoluminescence vs excitation density, we deduce a substantial enhancement of the external radiative efficiency of a nanowire array by adding microlenses. The enhanced radiative efficiency of the lensed nanowire array results in a clear enhancement of the open-circuit voltage for a subset of our solar cells. The microlenses finally also allow to increase the short-circuit current of our relatively short nanowires, providing a route to significantly reduce the amount of expensive semiconductor material. [ABSTRACT FROM AUTHOR]

Metal-Assisted Chemical Etching (MACE) is a technique for precisely forming nanostructures on semiconductor substrates, and it is actively researched in various fields such as electronic devices, optoelectronic devices, energy storage, and conversion systems. This process offers economic efficiency and effectiveness because it can be performed in a simple chemical laboratory environment without the need for expensive equipment. Particularly, MACE is recognized as an excellent technology for forming various nanostructures due to its advantage of precisely controlling the shape, size, and orientation of nanostructures compared to traditional etching techniques. MACE operates by inducing electrochemical reactions using a metal catalyst, selectively etching the semiconductor surface in a mixed solution of hydrofluoric acid (HF) and hydrogen peroxide ( H 2 O 2 ). The metal catalyst reacts with the oxidant to generate holes, which are injected into the semiconductor substrate to promote oxidation reactions. The oxidized material is then dissolved by HF, progressing the etching process. Precise nanostructures are formed only in the areas with the metal catalyst, and the etching results vary depending on the type, thickness, and deposition method of the catalyst. In this study, we comprehensively review the mechanism of the MACE process, the patterns of nanostructure formation according to the characteristics of catalysts and substrates, and the influence of process variables. We also analyze application cases of MACE in various semiconductor substrates such as silicon (Si), germanium (Ge), indium phosphide (InP), and gallium arsenide (GaAs), and examine the latest research trends and applications utilizing MACE. Nanostructures formed through MACE have the potential to maximize the performance of next-generation semiconductor and optoelectronic devices, and research in this area is expected to greatly contribute to the future development of the semiconductor industry. [ABSTRACT FROM AUTHOR]

This study investigates the growth of gallium arsenide nanowires, using lead as a catalyst. Typically, nanowires are grown through the vapor–solid–liquid mechanism, where a key factor is the reduction in the nucleation barrier beneath the catalyst droplet. Arsenic exhibits limited solubility in conventional catalysts; however, this research explores an alternative scenario in which lead serves as a solvent for arsenic, while gallium and lead are immiscible liquids. Liquid lead easily dissolves in Si as well as in GaAs. The preservation of the catalyst during the growth process is also addressed. GaAs nanowires have been grown by molecular beam epitaxy on silicon Si (111) substrates at varying temperatures. Observations indicate the spontaneous doping of the GaAs nanowires with both lead and silicon. These findings contribute to a deeper understanding of the VLS mechanism involved in nanowire growth. They are also an important step in the study of GaAs nanowire-doping processes. [ABSTRACT FROM AUTHOR]

In GaN‐on‐Si nanowire integration schemes, where the nanowires are contacted through the substrate, the interfaces between silicon substrate, AlN buffer layer, and GaN nanowire are of high interest. Herein, analysis by scanning transmission electron microscopy (STEM) of GaN nanowires grown on Si(111) by metal–organic vapor phase epitaxy using a polarity‐ and site‐controlled growth method is presented. This method is based on prestructuring the substrate, ex situ oxidation of the surface, and in situ oxide layer desorption. First, an AlN layer is grown to prevent melt‐back etching. Samples are prepared for STEM by focused ion beam cutting. STEM measurements in three different regions reveal that the AlN buffer material is polycrystalline. The degree of polycrystallinity is found to depend on the observed region: the highest degree exists at the field area between nanowires and the lowest at the sidewall of the Si‐pillars. On the sidewall, the c→$$ \overrightarrow{c} $$‐direction of the AlN grain is tilted by 30.1° with regard to the Si{111} sidewall plane, leading to reduced lattice mismatch at this location. The growth of GaN is competing with diffusion of Ga atoms through grain boundaries. The dominant mechanism is dependent on the region, leading to site‐controlled growth of nanowires. [ABSTRACT FROM AUTHOR]

This study reviews recent advancements in solar energy technologies, focusing on enhancing the efficiency of photovoltaic systems. Key research areas include optimizing material properties, improving charge separation, and addressing sustainability challenges. This study identifies critical challenges in quantum dot solar cell technology, such as modeling spectral absorption, managing thermal losses, and evaluating long-term stability. Overall, these innovations represent significant strides toward more efficient and environmentally friendly solar energy solutions. This Review article offers a thorough investigation of the direct current parameters in photovoltaic panels, aiming to boost their efficiency and cost-effectiveness in production. This study underscores the importance of precise modeling and identification of solar cell parameters to more effectively harness solar energy, thereby underscoring its potential for enhancing energy capacity and environmental conservation. Our research includes experimental data on polycrystalline silicon solar cells and simulation results of both individual and polycrystalline cells conducted using the NI Multisim simulator. The focal points of this study encompass the efficient use of solar energy, the pivotal role of silicon as a semiconductor material, and novel methods for augmenting photovoltaic cell efficiency, such as employing nanowires and multilayer semiconductors. This Review Article also examines the effect of temperature on solar cell efficiency and addresses both the theoretical and practical measures of key photovoltaic parameters, including short-circuit current, open-circuit voltage, fill factor, and conversion efficiency. [ABSTRACT FROM AUTHOR]

Innovative methods for substrate patterning provide intriguing possibilities for the development of devices based on ordered arrays of semiconductor nanowires. Control over the nanostructures' morphology in situ can be obtained via extensive theoretical studies of their formation. In this paper, we carry out an investigation of the ordered nanowires' formation kinetics depending on the growth mask geometry. Diffusion equations for the growth species on both substrate and nanowire sidewalls depending on the spacing arrangement of the nanostructures and deposition rate are considered. The value of the pitch corresponding to the maximum diffusion flux from the substrate is obtained. The latter is assumed to be the optimum in terms of the nanowire elongation rate. Further study of the adatom kinetics demonstrates that the temporal dependence of a nanowire's length is strongly affected by the ratio of the adatom's diffusion length on the substrate and sidewalls, providing insights into the proper choice of a growth wafer. The developed model allows for customization of the growth protocols and estimation of the important diffusion parameters of the growth species. [ABSTRACT FROM AUTHOR]

The electronic intrinsic surface states in wurtzite Zn-IV-N2 (with group- IV = Sn , Ge and Si) semiconductors were investigated using an intermediate-coupling variational approach considering the electron–surface optical phonon interaction influence. The intrinsic surface state energy distribution and the average penetrating depth of surface state eigen-wave function of the electron have been evaluated numerically by changing the surface potential barrier V 0 for wurtzite ZnSnN2, ZnGeN2 and ZnSiN2, respectively. The results show that the electronic intrinsic surface state energy increased linearly with increasing surface potential barrier V 0 for all the calculated materials. The result also indicated that the electronic intrinsic surface state energies variations due to the influence of electron–surface optical phonon interaction are dozens of meV. The average penetrating depth of electronic surface state eigen-wave function is independent of V 0 . Its value is no more than the corresponding material's lattice constant. The electronic scattering by surface optical phonon should be taken into account in the study of the intrinsic surface state of electrons in the group of Zn-IV-nitrides (with IV = Sn , Ge and Si) semiconductors, especially for materials having strong electron–phonon interaction and wide band gap. [ABSTRACT FROM AUTHOR]

A derivation of a tight-binding model from Schrödinger formalism for various topologies of position-based semiconductor qubits is presented in the case of static and time-dependent electric fields. The simplistic tight-binding model enables the description of single-electron devices at a large integration scale. The case of two electrostatically Wannier qubits (also known as position-based qubits) in a Schrödinger model is presented with omission of spin degrees of freedom. The concept of programmable quantum matter can be implemented in the chain of coupled semiconductor quantum dots. Highly integrated and developed cryogenic CMOS nanostructures can be mapped to coupled quantum dots, the connectivity of which can be controlled by a voltage applied across the transistor gates as well as using an external magnetic field. Using the anti-correlation principle arising from the Coulomb repulsion interaction between electrons, one can implement classical and quantum inverters (Classical/Quantum Swap Gate) and many other logical gates. The anti-correlation will be weakened due to the fact that the quantumness of the physical process brings about the coexistence of correlation and anti-correlation at the same time. One of the central results presented in this work relies on the appearance of dissipation-like processes and effective potential renormalization building effective barriers in both semiconductors and in superconductors between not bended nanowire regions both in classical and in quantum regimes. The presence of non-straight wire regions is also expressed by the geometrical dissipative quantum Aharonov–Bohm effect in superconductors/semiconductors when one obtains a complex value vector potential-like field. The existence of a Coulomb interaction provides a base for the physical description of an electrostatic Q-Swap gate with any topology using open-loop nanowires, with programmable functionality. We observe strong localization of the wavepacket due to nanowire bending. Therefore, it is not always necessary to build a barrier between two nanowires to obtain two quantum dot systems. On the other hand, the results can be mapped to the problem of an electron in curved space, so they can be expressed with a programmable position-dependent metric embedded in Schrödinger's equation. The semiconductor quantum dot system is capable of mimicking curved space, providing a bridge between fundamental and applied science in the implementation of single-electron devices. [ABSTRACT FROM AUTHOR]

Due to the suitable bandgap structure, efficient conversion rates of photon to electron, adjustable optical bandgap, high electron mobility/aspect ratio, low defects, and outstanding optical and electrical properties for device design, III–V semiconductors have shown excellent properties for optoelectronic applications, including photodiodes, photodetectors, solar cells, photocatalysis, etc. In particular, III–V nanostructures have attracted considerable interest as a promising photodetector platform, where high-performance photodetectors can be achieved based on the geometry-related light absorption and carrier transport properties of III–V materials. However, the detection ranges from Ultraviolet to Terahertz including broadband photodetectors of III–V semiconductors still have not been more broadly development despite significant efforts to obtain the high performance of III–V semiconductors. Therefore, the recent development of III–V photodetectors in a broad detection range from Ultraviolet to Terahertz, and future requirements are highly desired. In this review, the recent development of photodetectors based on III–V semiconductor with different detection range is discussed. First, the bandgap of III–V materials and synthesis methods of III–V nanostructures are explored, subsequently, the detection mechanism and key figures-of-merit for the photodetectors are introduced, and then the device performance and emerging applications of photodetectors are provided. Lastly, the challenges and future research directions of III–V materials for photodetectors are presented. [ABSTRACT FROM AUTHOR]

In this paper, we study a three-dimensional full hydrodynamic model in a bounded domain with insulating and adiabatic boundary. The model takes the form of nonisentropic Euler-Poisson system and incorporates recombination/generation terms, describing the bipolar transport of hot carriers in semiconductor optoelectronic devices. Of particular concern are the existence, uniqueness and exponential stability of thermal equilibrium states to the model, since these mathematical results are rendered useful in numerical simulation and physical theory of semiconductors. They are rigorously proved by the perturbation argument and energy method. [ABSTRACT FROM AUTHOR]

In this study, a novel synthesis of ultrathin, highly uniform colloidal bismuth sulfohalide (BiSX where X = Cl, Br, I) nanowires (NWs) and NW bundles (NBs) for room‐temperature and solution‐processed flexible photodetectors are presented. High‐aspect‐ratio bismuth sulfobromide (BiSBr) NWs are synthesized via a heat‐up method using bismuth bromide and elemental S as precursors and 1‐dodecanethiol as a solvent. Bundling of the BiSBr NWs occurs upon the addition of 1‐octadecene as a co‐solvent. The morphologies of the BiSBr NBs are easily tailored from sheaf‐like structures to spherulite nanostructures by changing the solvent ratio. The optical bandgaps are modulated from 1.91 (BiSCl) and 1.88 eV (BiSBr) to 1.53 eV (BiSI) by changing the halide compositions. The optical bandgap of the ultrathin BiSBr NWs and NBs exhibits blueshift, whose origin is investigated through density functional theory‐based first‐principles calculations. Visible‐light photodetectors are fabricated using BiSBr NWs and NBs via solution‐based deposition followed by solid‐state ligand exchanges. High photo‐responsivities and external quantum efficiencies (EQE) are obtained for BiSBr NW and NB films even under strain, which offer a unique opportunity for the application of the novel BiSX NWs and NBs in flexible and environmentally friendly optoelectronic devices. [ABSTRACT FROM AUTHOR]

Optoelectronic synapses, leveraging the integration of classic photo-electric effect with synaptic plasticity, are emerging as building blocks for artificial vision and photonic neuromorphic computing. However, the fundamental working principles of most optoelectronic synapses mainly rely on physical behaviors while missing chemical-electric synaptic processes critical for mimicking biorealistic neuromorphic functionality. Herein, we report a photoelectrochemical synaptic device based on p-AlGaN/n-GaN semiconductor nanowires to incorporate chemical-electric synaptic behaviors into optoelectronic synapses, demonstrating unparalleled dual-modal plasticity and chemically-regulated neuromorphic functions through the interplay of internal photo-electric and external electrolyte-mediated chemical-electric processes. Electrical modulation by implementing closed or open-circuit enables switching of optoelectronic synaptic operation between short-term and long-term plasticity. Furthermore, inspired by transmembrane receptors that connect extracellular and intracellular events, synaptic responses can also be effectively amplified by applying chemical modifications to nanowire surfaces, which tune external and internal charge behaviors. Notably, under varied external electrolyte environments (ion/molecule species and concentrations), our device successfully mimics chemically-regulated synaptic activities and emulates intricate oxidative stress-induced biological phenomena. Essentially, we demonstrate that through the nanowire photoelectrochemical synapse configuration, optoelectronic synapses can be incorporated with chemical-electric behaviors to bridge the gap between classic optoelectronic synapses and biological synapses, providing a promising platform for multifunctional neuromorphic applications. Integrating chemical-electric behaviors into optoelectronic synapses holds promise for several applications. Here, the authors report a photoelectrochemical synapse with dual-modal plasticity and chemically-regulated neuromorphic functions. [ABSTRACT FROM AUTHOR]

The measurement of the electronic bandgap and exciton binding energy in quasi-one-dimensional materials such as carbon nanotubes is challenging due to many-body effects and strong electron–electron interactions. Unlike bulk semiconductors, where the electronic bandgap is well known, the optical resonance in low-dimensional semiconductors is dominated by excitons, making their electronic bandgap more difficult to measure. In this work, we measure the electronic bandgap of networks of polymer-wrapped semiconducting single-walled carbon nanotubes (s-SWCNTs) using non-ideal p-n diodes. We show that our s-SWCNT networks have a short minority carrier lifetime due to the presence of interface trap states, making the diodes non-ideal. We use the generation and recombination leakage currents from these non-ideal diodes to measure the electronic bandgap and excitonic levels of different polymer-wrapped s-SWCNTs with varying diameters: arc discharge (~1.55 nm), (7,5) (0.83 nm), and (6,5) (0.76 nm). Our values are consistent with theoretical predictions, providing insight into the fundamental properties of networks of s-SWCNTs. The techniques outlined here demonstrate a robust strategy that can be applied to measuring the electronic bandgaps and exciton binding energies of a broad variety of nanoscale and quantum-confined semiconductors, including the most modern nanoscale transistors that rely on nanowire geometries. [ABSTRACT FROM AUTHOR]

We study theoretically the Josephson diode effect (JDE) when realized in a system composed of parallel-coupled double-quantum dots (DQDs) sandwiched between two semiconductor nanowires deposited on an s-wave superconductor surface. Due to the combined effects of proximity-induced superconductivity, strong Rashba spin–orbit interaction, and the Zeeman splitting inside the nanowires, a pair of Majorana bound states (MBSs) may possibly emerge at opposite ends of each nanowire. Different phase factors arising from the superconductor substrate can be generated in the coupling amplitudes between the DQDs and MBSs prepared at the left and right nanowires, and this will result in the Josephson current. We find that the critical Josephson currents in positive and negative directions are different from each other in amplitude within an oscillation period with respect to the magnetic flux penetrating through the system, a phenomenon known as the JDE. It arises from the quantum interference effect in this double-path device, and it can hardly occur in the system of one QD coupled to MBSs. Our results also show that the diode efficiency can reach up to 50 % , but this depends on the overlap amplitude between the MBSs, as well as the energy levels of the DQDs adjustable by gate voltages. The present model is realizable within current nanofabrication technologies and may find practical use in the interdisciplinary field of Majorana and Josephson physics. [ABSTRACT FROM AUTHOR]

The properties of most III–V semiconductor materials in the wurtzite structure are not known because of their metastable character. However, recent advances in the growth of III–V wurtzite nanorods open new perspectives for applications. In this work, we present a systematic computational study of bulk wurtzite III–V semiconductors, using predictive ab initio methods, to provide a necessary base knowledge for studying the nanostructures. The most important physical properties of bulk systems, i.e., lattice constants, elasticity, spontaneous polarization, piezoelectricity, band structures, deformation potentials, and band offsets, have been studied. Comparison with the available experimental and theoretical data shows the high credibility of our results. Moreover, we provide a complete set of parameters for a six-band k ⋅ p model, which is widely used for simulating devices based on semiconductor heterostructures. [ABSTRACT FROM AUTHOR]

We report the effects of Si doping on the growth dynamics and size distribution of entirely catalyst-free GaAs nanowire (NW) arrays grown by selective area molecular beam epitaxy on SiO2-masked Si (111) substrates. Surprising improvements in the NW-array uniformity are found with increasing Si doping, while the growth of undoped NWs appears in a metastable regime, evidenced by large size and shape distributions, and the simultaneous presence of crystallites with tetrahedral termination. Correlating scanning electron microscopy and transmission electron microscopy investigations, we propose that the size and shape distributions are strongly linked to the underlying twin defect formation probabilities that govern the growth. Under the present growth conditions, Si-doping of GaAs NWs leads to a very high twin defect formation probability (∼0.4), while undoped NWs exhibit a nearly threefold decreased probability (∼0.15). By adopting a model for facet-mediated growth, we describe how the altered twin formation probabilities impact the competing growth of the relevant low-index NW facets, and hence, NW size and shape. Our model is further supported by a generic Monte Carlo simulation approach to highlight the role of twin defects in reproducing the experimentally observed size distributions. [ABSTRACT FROM AUTHOR]

GaN nanostructures are promising for a broad range of applications due to their 3D structure, thereby exposing non-polar crystal surfaces. The nature of the exposed crystal facets, i.e., whether they are a-, m-plane, or of mixed orientation, impacts the stability and performance of GaN nanostructure-based devices. In this context, it is of great interest to control the formation of well-defined side facets. Here, we show that we can control the crystal facet formation at the nanowire sidewalls by tuning the III–V ratio during selective area growth by molecular beam epitaxy. Especially, the N flux serves as a tool for controlling the growth kinetics. In addition, we demonstrate the growth of GaN nanofins with either a- or m-plane side facets. Based on our observations, we present the underlying nanostructure growth mechanisms. Low temperature photoluminescence measurements show a correlation of the formation of structural defects like stacking faults with the growth kinetics. This article demonstrates the controlled selective epitaxy of GaN nanostructures with defined crystal side facets on large-scale available AlN substrates. [ABSTRACT FROM AUTHOR]

Semiconductor nanowires have inspired plenty of novel nanotechnology device concepts in photonics, electronics, and sensing, owing to their unique functionalities and integrability in heterogeneous platforms. Lattice‐mismatched core/shell heterostructures, in particular, open new avenues for strain engineering and material properties modification. A notable case is the widely tunable tensile strain in the core of GaAs/InxAl1‐xAs core/shell nanowires, which can be used to tailor the GaAs bandgap for applications across near‐infrared, like optical fiber telecommunication, imaging, photovoltaics, etc. As it is shown here, though, the bandgap narrowing under high tensile strain in the GaAs core is accompanied by fast non‐radiative recombination, which is undesirable for any device application. The limiting role of the lattice‐mismatched core/shell interface is revealed, and a novel core/dual‐shell heterostructure that employs an intermediate AlyGa1‐yAs shell (spacer) is proposed. This spacer decouples the GaAs/AlyGa1‐yAs interface, which confines electrons and holes into GaAs, from the lattice‐mismatched AlyGa1‐yAs/InxAl1‐xAs one, whereas the strain in GaAs is unaffected. Choosing the optimal spacer thickness, the photoluminescence yield increases significantly, with longer emission decay lifetimes and slower carrier cooling rates. Besides unlocking the potential of GaAs for photonic applications across near‐infrared, the proposed heterostructure concept can also be adopted for other material systems. [ABSTRACT FROM AUTHOR]

Degeneracy and symmetry have a profound relation in quantum systems. Here, we report gate-tunable subband degeneracy in PbTe nanowires with a nearly symmetric cross-sectional shape. The degeneracy is revealed in electron transport by the absence of a quantized plateau. Utilizing a dual gate design, we can apply an electric field to lift the degeneracy, reflected as emergence of the plateau. This degeneracy and its tunable lifting were challenging to observe in previous nanowire experiments, possibly due to disorder. Numerical simulations can qualitatively capture our observation, shedding light on device parameters for future applications. [ABSTRACT FROM AUTHOR]

Broadband photodetection, spanning from ultraviolet (UV) to infrared (IR), is pivotal in diverse technological domains including astronomy, remote sensing, environmental monitoring, and medical diagnostics. However, current commercially available broadband photodetectors, predominately based on conventional narrow-bandgap semiconductors, exhibit limited sensitivity in the UV region. This limitation, stemming from the significant energy disparity between the semiconductor bandgap and UV photon, narrows their application scope. Herein, we report an innovative approach involving the in-situ van der Waals (vdW) integration of two-dimensional (2D) GeSe2 layers onto a Si substrate. This process yields a high-quality GeSe2/Si vdW heterojunction device, which features a broad response range covering from UV to near-IR (NIR) with a greatly-enhanced sensitivity in the UV region. The device possesses high responsivities of 325 and 533.4 mA/W, large detectivities of 1.24 × 1013 and 2.57 × 1013 Jones, and fast response speeds of 20.6/82.1 and 17.7/81.0 µs under 360 and 980 nm, respectively. Notably, the broadband image sensing and secure invisible optical communication capabilities of the GeSe2/Si heterojunction device are demonstrated. Our work provides a viable approach for UV-enhanced broadband photodetection technology, opening up new possibilities and applications across various scientific and technological domains. [ABSTRACT FROM AUTHOR]

A one‐dimensional (1D) multifluid population balance model approach is presented as a compromise between computational effort and accuracy. The approach is used to test process scenarios, perform sensitivity analysis, and provide a reliable reactor scale‐up and optimization tool. The article focuses on a mini‐plant batch bubble column, where the scale‐up behavior in terms of bubble column height, gas flux, and composition of the liquid phase is investigated. Although simplifications were made, the model requires calibration to experimental data using different calibration methods. An optimal calibration procedure is found that minimizes experimental effort while maximizing scalability. The model was tested on various liquid‐phase compositions, and it was found to reproduce experimental data accurately. However, the model cannot reproduce flow regime changes and does not perform well across substance systems. The study shows that the applied 1D multifluid population balance approach is a valuable and reliable tool in multiphase reactor scale‐up and optimization. [ABSTRACT FROM AUTHOR]

(In, Ga) alloy droplets are used to catalyse the growth of (In, Ga)As nanowires by molecular beam epitaxy on Si(111) substrates. The composition, morphology and optical properties of these nanowires can be tuned by the employed elemental fluxes. To incorporate more than 10% of In, a high In/(In+Ga) flux ratio above 0.7 is required. We report a maximum In content of almost 30% in bulk (In, Ga)As nanowires for an In/(In+Ga) flux ratio of 0.8. However, with increasing In/(In+Ga) flux ratio, the nanowire length and diameter are notably reduced. Using photoluminescence and cathodoluminescence spectroscopy on nanowires covered by a passivating (In, Al)As shell, two luminescence bands are observed. A significant segment of the nanowires shows homogeneous emission, with a wavelength corresponding to the In content in this segment, while the consumption of the catalyst droplet leads to a spectrally-shifted emission band at the top of the nanowires. The (In,Ga)As nanowires studied in this work provide a new approach for the integration of infrared emitters on Si platforms. [ABSTRACT FROM AUTHOR]

Exploitation of low‐dimensional metal‐oxide semiconductor nanowires (MOS NWs) with peculiar and radial coaxial architectures is of great significance for constructing nanoscale, high‐performance, multi‐module integrable functional electronic products. Here, highly ordered In2O3@ZnO coaxial NW arrays (CNWA) using a simple and economical electrospinning technique are synthesized and assembled into field‐effect transistors (FETs). Featuring strong carrier effusion efficiency at the In2O3@ZnO circular heterogeneous interface, the field effect mobility (εFE) gets an intrinsic improvement and can reach as high as 202.3 cm2 V‒1 s‒1 for high‐k‐based CNWA FETs, which exceeds the performance of oxide‐based FETs devices reported by far. Furthermore, the unique structural advantages endowing In2O3@ZnO CNWA FETs with excellent optoelectronic coupling capabilities are identified, for which further optoelectronic detection and artificial photonic synaptic devices are constructed and functional simulations are implemented. This work offers new insights in designing optoelectronics and artificial synapses to process and recognize information for neuromorphic computing and artificial intelligence applications. [ABSTRACT FROM AUTHOR]

Organic semiconductors have significant potential for wearable optoelectronics due to their designable molecular structures, tunable photoelectronic properties, and flexibility. For their integration into optoelectronic devices, organic semiconductors need to be assembled into single‐crystalline arrays with both precise alignment of micro‐/nanostructures and long‐range order of molecules. In this study, an interface‐confined lithography technique is developed for fabricating organic single‐crystalline microwire arrays with layered molecular stacking and ordered crystallographic orientation toward wearable UV radiation monitor. This interface‐confined strategy introduces parallel gas–liquid–solid three‐phase contact line (TPCL) arrays to suppress the lateral growth of single crystals. Meanwhile, TPCLs with controlled dewetting direction promote longitudinal growth, thus universally yielding 1D arrays based on various organic semiconducting small molecules. These 1D single‐crystalline arrays exhibit high average mobility of 12.5 cm2 V−1 s−1 with uniform electronic properties of 9.3% variation, and good mechanical stability after 1000 bending times. Based on organic 1D arrays, wearable devices with robust photoresponsivity of 8.26 × 103 A W−1 and high mechanical flexibility achieve real‐time monitoring of UV radiation to prevent skin disease. This confined‐assembly strategy opens a new avenue to construct wearable optoelectronic devices for health monitoring. [ABSTRACT FROM AUTHOR]

Leaky mode resonances of the setae of Cataglyphis bombycina are found to enhance the thermal emission of the animals by near field coupling to the chitinous exoskeleton. This is remarkable, as the setae are also an adaption to enhance the reflectivity in the visible wavelength range. Both effects are dependent on morphology, dimensions and spatial arrangement. These parameters were experimentally characterized and simulated by finite difference time domain simulations to elucidate the optical impact of the setae in the mid infrared range and the contribution of leaky mode resonances. This mode of action and the setae's optical properties in the visible range explain evolutionary strains that led to the actual morphology and size of the setae. [ABSTRACT FROM AUTHOR]

The proof of strong two-dimensional lateral quantum confinement in the In-rich core of red-light emitting self-formed core–shell InGaN nanowires is given. The nanowires are directly grown on Si (111) by plasma-assisted molecular beam epitaxy. After the initial InGaN nucleation, straight nanowires with quantum-size core radius determined by x-ray diffraction, transmission electron microscopy, and energy dispersive x-ray mappings develop. Detailed comparison of the photoluminescence from the core, the In contents of the core and shell, and the core radius with theoretical modeling reveals a parabolic confinement potential with large ground state quantum confinement energies of electrons and holes. Such strong lateral quantum confinement in a vertical quantum wire active region is ideal for the performance of optoelectronic devices, in particular of our reported red InGaN light emitting diode with high brightness and color stability. [ABSTRACT FROM AUTHOR]

As a new functional material, metal halide perovskites provide new possibilities for preparing gain media for nanosemiconductor lasers. This paper reviews the fabrication results of nanosemiconductor lasers based on metal halide perovskite materials. Firstly, three standard metal halide perovskite-based nanosemiconductor lasers are described: thin-film, nanowire, and quantum dot lasers. Under the corresponding gain structure of each laser, the appropriate gain dielectric material is discussed, and its application in the fabrication of nanosemiconductor lasers is discussed. On this basis, the effects of these gain structures and metal halide perovskite materials on the performance of nanosemiconductor lasers and related application progress are analyzed. Finally, the challenges and opportunities of nanosemiconductor lasers based on metal halide perovskite materials are summarized and the future development trend was discussed. [ABSTRACT FROM AUTHOR]

Highlights: A novel photoelectrochemical (PEC) photosensor composed of GaN nanowire-on-Si platform demonstrates record-high responsivity of 247.8 mA W−1 with ultra-stable operation characteristics. Strategic internal and external band structure engineering of semiconductor nanowires promotes efficient PEC reaction via controlling carrier dynamics while preserving nanowires from material degradation. The glucose sensing system is constructed to successfully analyze blood glucose levels in real human serum samples, featuring a high sensitivity of 0.173 µA µM−1 cm−2 and a low detection limit of 0.07 µM. Photosensors with versatile functionalities have emerged as a cornerstone for breakthroughs in the future optoelectronic systems across a wide range of applications. In particular, emerging photoelectrochemical (PEC)-type devices have recently attracted extensive interest in liquid-based biosensing applications due to their natural electrolyte-assisted operating characteristics. Herein, a PEC-type photosensor was carefully designed and constructed by employing gallium nitride (GaN) p–n homojunction semiconductor nanowires on silicon, with the p-GaN segment strategically doped and then decorated with cobalt–nickel oxide (CoNiOx). Essentially, the p–n homojunction configuration with facile p-doping engineering improves carrier separation efficiency and facilitates carrier transfer to the nanowire surface, while CoNiOx decoration further boosts PEC reaction activity and carrier dynamics at the nanowire/electrolyte interface. Consequently, the constructed photosensor achieves a high responsivity of 247.8 mA W−1 while simultaneously exhibiting excellent operating stability. Strikingly, based on the remarkable stability and high responsivity of the device, a glucose sensing system was established with a demonstration of glucose level determination in real human serum. This work offers a feasible and universal approach in the pursuit of high-performance bio-related sensing applications via a rational design of PEC devices in the form of nanostructured architecture with strategic doping engineering. [ABSTRACT FROM AUTHOR]

Defect fluorescence from high aspect ratio semiconductor nanowires typically displays a weak polarization parallel to the nanowire's long axis due to dielectric mismatch in high aspect ratio media. Instead, anomalous 2.2 eV defect fluorescence distinctly polarized perpendicular to the nanowire is observed and measured from carbon-incorporated zinc oxide nanowires. These observations are significant because polarized defect emissions with consistent polarization on a mesoscopic scale are uncommon. Through a systematic study and comparison of experimental results with density functional theory calculations, an oriented defect complex comprising carbon substituting on an oxygen site and an oxygen vacancy (CO-VO) is deduced to be responsible for the anomalous yellow fluorescence, demonstrating a method for relating atomic-scale defect geometry to mesoscopic properties. The anomalous emission can appear in both green- and red-fluorescing nanowires grown with different carbon concentrations, verifying the independence and uniqueness of the 2.2 eV emission. This allows for polarization-dependent emission wavelength selection from a single nanowire. [ABSTRACT FROM AUTHOR]

The article explores recent advancements in material science, quantum technology, and biosynthesis. Topics discussed include stress-assisted growth of metal nanowires using ion beam implantation, the use of lanthanide complexes for enhanced quantum sensing, and the discovery of massive polyketide synthase enzymes in marine microbes.

This study investigates the growth of gallium arsenide nanowires, using lead as a catalyst. Typically, nanowires are grown through the vapor–solid–liquid mechanism, where a key factor is the reduction in the nucleation barrier beneath the catalyst droplet. Arsenic exhibits limited solubility in conventional catalysts; however, this research explores an alternative scenario in which lead serves as a solvent for arsenic, while gallium and lead are immiscible liquids. Liquid lead easily dissolves in Si as well as in GaAs. The preservation of the catalyst during the growth process is also addressed. GaAs nanowires have been grown by molecular beam epitaxy on silicon Si (111) substrates at varying temperatures. Observations indicate the spontaneous doping of the GaAs nanowires with both lead and silicon. These findings contribute to a deeper understanding of the VLS mechanism involved in nanowire growth. They are also an important step in the study of GaAs nanowire-doping processes.

Analytical expressions for the low-field mobility in heavily doped 3D, 2D, and 1D semiconductor structures are obtained using the quantum-kinetic approach. The study takes into account the multi-ion (M-ion) scattering of charge carriers by ionized impurities. The calculated dependences of the carrier mobility on doping concentration are compared with experiment in the heavily doped bulk materials (3D) Si, InP, GaAs, n-In0.49Ga0.51P, in heavily doped In0.15Ga0.85As quantum wells and InN nanowires, respectively. When calculating mobility in n-Si, the anisotropic effective masses of electrons in the valleys are taken into account. We explain the difference in the electron mobility of n-Si bulk crystals heavily doped by phosphorus and arsenic in the framework of the M-ion scattering model, which considers the scattering of electrons by interaction potentials with two characteristic lengths: the screening length and the effective radius of the doping ion. The number of ions M participating in the scattering process depends on the effective masses of charge carriers. For the light carriers with effective masses m < 0.1 m 0 (m 0 is the free electron mass), the two-ion (M = 2) scattering is more probable. For carriers with higher effective masses, three- and four-ion scattering is relevant. [ABSTRACT FROM AUTHOR]

Confining light at a subwavelength scale is important for building ultracompact opto-electronic networks. Plasmonic waveguides are good candidate devices for this purpose. However, the oscillation of electrons relating to surface plasmon polaritons causes energy dissipation, which limits the propagation length and thus reduces the waveguide performance. Here, we design a low-loss plasmonic waveguide composed of a nanowire dimer structure on a metal substrate, in which the dominant modes are localized within the air gap between the nanowires and referred to as air-host plasmonic modes. The use of air instead of dielectric materials as the host medium can reduce ohmic loss and avoid the dispersion effect of dielectric.When the constructed nanowires have a diameter less than 100 nm, the air-host mode has subwavelength-scale confinement and a propagation length of ~100 µm, which has broad application prospects for the construction of ultracompact plasmonic devices. [ABSTRACT FROM AUTHOR]

This document is a summary of a special issue of the journal Materials titled "Advances in Plasma and Laser Engineering." The special issue focuses on the role of plasma and laser-based techniques in materials science, particularly in nanotechnology. The articles in the special issue cover a range of topics, including plasma etching and treatment of silicon and polyurethane, as well as laser processing of steel and silicon. The authors discuss the potential applications of plasma and laser techniques in various fields, such as electronics, energy, medicine, and construction. The document also suggests future challenges and opportunities for research in plasma and laser engineering, including the integration of plasma and laser technologies and the use of novel plasma and laser techniques. [Extracted from the article]

Numerous optoelectronic devices based on low-dimensional nanostructures have been developed in recent years. Among these, pyramidal low-dimensional semiconductors (zero- and one-dimensional nanomaterials) have been favored in the field of optoelectronics. In this review, we discuss in detail the structures, preparation methods, band structures, electronic properties, and optoelectronic applications (photocatalysis, photoelectric detection, solar cells, light-emitting diodes, lasers, and optical quantum information processing) of pyramidal low-dimensional semiconductors and demonstrate their excellent photoelectric performances. More specifically, pyramidal semiconductor quantum dots (PSQDs) possess higher mobilities and longer lifetimes, which would be more suitable for photovoltaic devices requiring fast carrier transport. In addition, the linear polarization direction of exciton emission is easily controlled via the direction of magnetic field in PSQDs with C3v symmetry, so that all-optical multi-qubit gates based on electron spin as a quantum bit could be realized. Therefore, the use of PSQDs (e.g., InAs, GaN, InGaAs, and InGaN) as effective candidates for constructing optical quantum devices is examined due to the growing interest in optical quantum information processing. Pyramidal semiconductor nanorods (PSNRs) and pyramidal semiconductor nanowires (PSNWRs) also exhibit the more efficient separation of electron-hole pairs and strong light absorption effects, which are expected to be widely utilized in light-receiving devices. Finally, this review concludes with a summary of the current problems and suggestions for potential future research directions in the context of pyramidal low-dimensional semiconductors. [ABSTRACT FROM AUTHOR]

Silica-on-silicon is a major optical integration platform, while the emergent class of the integrated laser-written circuits' platform offers additionally high customizability and flexibility for rapid prototyping. However, the inherent waveguides' low core/cladding refractive index contrast characteristic, compared to other photonic platforms in silicon or silicon nitride, sets serious limitations for on-chip efficient coupling with single photon emitters, like semiconductor nanowires with quantum dots, limiting the applications in quantum computing. A new light coupling scheme proposed here overcomes this limitation, providing means for light coupling >50%. The scheme is based on the incorporation of an optical microsphere between the nanowire and the waveguide, which is properly optimized and arranged in terms of size, refractive index, and the distance of the microsphere between the nanowire and waveguide. Upon suitable design of the optical arrangement, the photonic nanojet emitted by the illuminated microsphere excites efficiently the guided eigenmodes of the input channel waveguide, thus launching light with high-coupling efficiency. The method is tolerant in displacements, misalignments, and imperfections and is fabricationally feasible by the current state of art techniques. The proposed method enables the on-chip multiple single photon emitters' integration, thus allowing for the development of highly customizable and scalable quantum photonic-integrated circuits for quantum computing and communications. [ABSTRACT FROM AUTHOR]

To enable the application to next-generation devices of semiconductor nanowires (NWs), it is important to control their formation and tune their functionality by doping and the use of heterojunctions. In this paper, we introduce formation and the characterization methods of nanowires, focusing on our research results. We describe a top-down method of controlling the size and alignment of nanowires that shows advantages over bottom-up growth methods. The latter technique causes damage to the nanowire surfaces, requiring defect removal after the NW formation process. We show various methods of evaluating the bonding state and electrical activity of impurities in NWs. If an impurity is doped in a NW, mobility decreases due to the scattering that it causes. As a strategy for solving this problem, we describe research into core–shell nanowires, in which Si and Ge heterojunctions are formed in the diameter direction inside the NW. This structure can separate the impurity-doped region from the carrier transport region, promising as a channel for the new ultimate high-mobility transistor. [ABSTRACT FROM AUTHOR]

Multi-junction photovoltaics approaches are being explored to mitigate thermalization losses that occur in the absorption of high-energy photons. However, the design of tandem cells faces challenges such as light reflection and parasitic absorption. Nanostructures have emerged as promising solutions due to their anti-reflection properties, which enhances light absorption. III-V nanowires (NWs) solar cells can achieve strong power conversion efficiencies, offering the advantage of potentially integrating tunnel diodes within the same fabrication process. Metal halide perovskites (MHPs) have gained attention for their optoelectronic attributes and cost-effectiveness. Notably, both material classes allow for tunable bandgaps. This study explores the integration of MHPs with III-V NWs solar cells in both two-terminal and three-terminal configurations. Our primary focus lies in the optical analysis of a tandem design using III-V semiconductor nanowire arrays in combination with perovskites, highlighting their potential for tandem applications. The space offered by the compact footprint of NW arrays is used in an interpenetrated tandem structure. We systematically optimize the bottom cell, addressing reflectivity and parasitic absorption, and extend to a full tandem structure, considering experimentally feasible thicknesses. Simulation of a three-terminal structure highlights a potential increase in efficiency, decoupling the operating points of the subcells. The two-terminal analysis underscores the benefits of nanowires in reducing reflection and achieving a higher matched current between the top and the bottom cells. This research provides significant insights into NW tandem solar cell optics, enhancing our understanding of their potential to improve photovoltaic performance. [ABSTRACT FROM AUTHOR]

We demonstrate the facile fabrication of metal-wire-embedded microtrenches interconnected with semiconducting ZnO nanowires (ZNWs) through the continuous mechanical machining of micrograting trenches, the mechanical embedding of solution-processable metal wires therein, and the metal-mediated hydrothermal growth of ZNWs selectively thereto. The entire process can be performed at room or a very low temperature without resorting to vacuum, lithography, and etching steps, thereby enabling the use of flexible polymer substrates of scalable sizes. We optimize the fabrication procedure and resulting structural characteristics of this nanowire-interconnected flexible trench-embedded electrode (NIFTEE) architecture. Specifically, we carefully sequence the coating, baking, and doctor-blading of an ionic metal solution for the embedding of clean metal wires, and control the temperature and time of the hydrothermal ZNW growth process for faithful interconnections of such trench-embedded metal wires via high-density ZNWs. The NIFTEE structure can function as a bending-sensitive optoelectronic sensor, as the number of ZNWs interconnecting the neighboring metal wires changes upon mechanical bending. It may benefit further potential applications in diverse fields such as wearable technology, structural health monitoring, and soft robotics, where bending-sensitive devices are in high demand. [ABSTRACT FROM AUTHOR]

In this study, a one-dimensional defective photonic structure for the detection of magnetic fluid in the presence of an external magnetic field has been theoretically examined by using TMM. The principle of capillary action has been used for injecting the magnetic fluid under consideration into the cavity region of the proposed photonic structure. The sensing capability of the structure has been examined by analyzing the presence of defect mode inside the photonic bandgap of the structure under normal incidence condition only for neglecting the problems involved during oblique incidence. We have optimized the thickness of the cavity layer as 670 nm in order to achieve high value of sensitivity 312.50 nm/RIU from the proposed design under the influence of an external magnetic field of value 210 Oe. Apart from sensitivity, we have also examined figure-of-merit and quality factor values of the suggested design to establish support toward our claim of designing of sensitive magnetic sensor composed of one-dimensional defective photonic structure. The work can be used for designing of some novel photonic structures for sensing and detection of magnetic field strength via magnetic fluid. [ABSTRACT FROM AUTHOR]

The adaptability of living organisms to dynamically adjust their biological behavior in response to fluctuating surroundings is a prerequisite for their evolutionary success. However, artificially‐synthesized materials, especially semiconductors, have not been able to replicate such adaptability due to their inherent physical rigidity and lack of intrinsic structural responsiveness to external stimuli. Herein, an adaptive structural evolution in group‐III‐nitride semiconductors is demonstrated by constructing an AlGaN‐nanowire/Ni(OH)2 symbiotic‐system, resulting in self‐improved optoelectronic characteristics. The mutualistic interplay between AlGaN and Ni(OH)2 nanostructure leads to the adaptive evolution of crystalline‐facets of AlGaN‐nanowires, along with self‐optimization of Ni(OH)2 nanocrystals upon photon‐irradiation during its operation. Specifically, the nanowire‐surfaces dynamically evolve during Ni(OH)2 photo‐deposition, removing the (0001¯$\bar{1}$) plane while exposing the (101¯1¯$\bar{1}\bar{1}$), which facilitates carrier transport at AlGaN/Ni(OH)2 interface. Moreover, light‐induced electrons generated from AlGaN‐nanowires then partially reduce Ni2+ ions in the Ni(OH)2 nanostructure into Ni0 nanometals, which further boosts the proton reduction thermodynamics, generating an unusual self‐improving photocurrent from −59.6 to −101.6 µA cm−2. Such a "symbiotic system," which is barely observed in conventional semiconductors, provides a promising avenue toward realizing smart adaptive semiconductors that are capable of dynamic structural evolution to fully unleash their potential for emerging optoelectronic and artificial‐photocatalysis applications. [ABSTRACT FROM AUTHOR]

The simultaneous control of the orientation and position of organic semiconductor nanowires remains a major challenge when integrating them into monolithic devices. In this study, tris(8‐hydroxyquinoline)aluminum(III) (Alq3) molecules are self‐assembled into single‐crystalline nanowires with consistent orientation and predictable positions by selective‐area graphoepitaxial growth. The nanowire orientation is determined by parallel nanogrooves on a periodically modified faceted sapphire surface, and the position is simultaneously defined using a shadow mask. Computational fluid dynamics simulations showed that the mass flow field over the sapphire surface is tailored by the mask, resulting in preferential nanowire nucleation around the hole centers and leaving sufficient free space for the subsequent growth. Accordingly, the number, length, and density of the nanowires can be controlled by adjusting the mask layout. The good alignment and predictable positions of these nanowires facilitated their subsequent device integration, eliminating laborious assembly steps and potential damage after nanowire growth. Measurements from an in situ integrated two‐terminal device based on the Alq3 nanowires revealed that the nanowires exhibit a remarkable negative differential resistance and fast photoresponse in the UV region. Overall, selective‐area graphoepitaxial growth provides a versatile protocol for fabricating site‐ and orientation‐controlled organic semiconductor nanowires for the monolithic fabrication of nanowire‐based devices. [ABSTRACT FROM AUTHOR]

The adiabatic topological pumping is proposed by periodically modulating a semiconductor nanowire double-quantum-dot chain. We demonstrate that the quantized charge transport can be achieved by a nontrivial modulation of the quantum-dot well and barrier potentials. When the quantum-dot well potential is replaced by a time-dependent staggered magnetic field, the topological spin pumping can be realized by periodically modulating the barrier potentials and magnetic field. We also demonstrate that in the presence of Rashba spin–orbit interaction, the double-quantum-dot chain can be used to implement the topological spin pumping. However, the pumped spin in this case can have a quantization axis other than the applied magnetic field direction. Moreover, we show that all the adiabatic topological pumping are manifested by the presence of gapless edge states traversing the bandgap as a function of time. [ABSTRACT FROM AUTHOR]

This document is an editorial letter from the journal Nanomaterials, titled "Advanced Spintronic and Electronic Nanomaterials." It discusses the increasing prevalence of two-dimensional (2D) layered electronic materials, such as graphene, and their applications in spintronics, flexible electronics, and information science. The letter also highlights the rapid development of spintronics and electronics in the past two decades, particularly the discovery of two-dimensional ferromagnetism. The document introduces a special issue of the journal that includes research articles and review articles on advanced spintronic and electronic nanomaterials, covering topics such as vortex resonance, tunneling magnetoresistance, superconducting properties, and strain engineering. The authors express their gratitude to the authors, reviewers, and editorial staff involved in the creation of the special issue. [Extracted from the article]

Ballistic thermal transport is a remarkable nanoscale phenomenon with possible applications in microelectronics. In the past decade, research on ballistic thermal transport focused on the measurements of length-dependent thermal conductivity in semiconductor nanowires. In this Perspective article, we review the experimental demonstrations of this phenomenon in nanowires of various materials and sizes and at different temperatures. Our literature analysis reveals a controversy between works reporting two distinct pictures of ballistic conduction: perfectly ballistic conduction even at room temperature and weak quasi-ballistic conduction mainly below room temperature. Simulations seem to support the weaker version of the effect. Thus, future experiments are expected to resolve this controversy. [ABSTRACT FROM AUTHOR]