Materials For Nanoelectronics Research Articles

Fully spin-polarized two dimensional polar semi-metallic phase in Eu substituted GdI2 monolayer

Abstract The coexistence of seemingly mutually exclusive properties such as ferromagnetism, ferroelectricity and metallicity in atomically thin materials is the requirement of the hour in electronics as the Moore’s law faces an impending end. Only a few 2D multiferroic materials have been predicted/realized so far. The polar metals with simultaneous presence of polarity and conductivity are also equally rare. Here, we predict, based on first-principles calculations that an Eu-substituted rare-earth halide GdI2 monolayer showcases ferromagnetism, ferroelasticity while being polar and a fully spin-polarized semi-metal at the same time. The ferroelasticity and polarity are shown to be coupled making it possible to switch the polar direction using external mechanical stress. Further, it is observed that an application of biaxial tensile strain of 5% causes the spin easy-axis to shift from out-of-plane to in-plane direction. Thus, spin easy axis gets coupled with the direction of polarization in the strained monolayer making the switching of magnetization also possible using external strain. Simultaneous coexistence and coupling of the ferroic orders in a metallic 2D material makes the Eu substituted GdI2 monolayer an incredibly rare material for nano-electronics and spintronics applications.

Two-Dimensional Materials in Nanomaterials: Properties, Applications, and Prospects

Recently, two-dimensional (2D) materials have garnered significant attention in nanomaterials research because of their unique physical and chemical properties. This paper examines the research background, core properties, main application areas, and future prospects of 2D materials. Through a systematic literature review and case studies, this paper summarizes the main advances and challenges in current 2D material research. The research methodology includes a literature review and case study analysis, aiming to uncover the potential of 2D materials in nanoelectronics, optoelectronic devices, energy storage, and biomedicine. The research questions address the fundamental properties of 2D materials, their practical applications, and strategies to overcome existing challenges. The results indicate that while 2D materials like graphene and transition metal dichalcogenides (TMDs) exhibit excellent electronic, optical, and mechanical properties, they still encounter significant challenges in material preparation, performance tuning, and environmental safety. This paper proposes potential solutions and predicts the future applications of 2D materials in emerging technologies. The conclusion asserts that with the continuous discovery of novel 2D materials and technological advancements, 2D materials will play a crucial role in science and industry.

(Invited) Enabling Bio-Realistic Artificial Intelligence Hardware with Neuromorphic Nanoelectronics

The exponentially improving performance of digital computers has recently slowed due to the speed and power consumption issues resulting from the von Neumann bottleneck. In contrast, neuromorphic computing aims to circumvent these limitations by spatially co-locating logic and memory in a manner analogous to biological neuronal networks [1]. Beyond reducing power consumption, neuromorphic devices provide efficient architectures for image recognition, machine learning, and artificial intelligence [2]. This talk will explore how low-dimensional nanoelectronic materials enable gate-tunable neuromorphic devices [3]. For example, by utilizing self-aligned, atomically thin heterojunctions, dual-gated Gaussian transistors have been realized, which show tunable anti-ambipolarity for artificial neurons, competitive learning, spiking circuits, and mixed-kernel support vector machines [4,5]. In addition, field-driven defect motion in polycrystalline monolayer MoS2 enables gate-tunable memristive phenomena that serve as the basis of hybrid memristor/transistor devices (i.e., ‘memtransistors’) that concurrently provide logic and data storage functions [6]. The planar geometry of memtransistors further allows multiple contacts and dual gating that mimic the behavior of biological systems such as heterosynaptic responses [7]. Moreover, control over polycrystalline grain structure enhances the tunability of potentiation and depression, which enables unsupervised continuous learning in spiking neural networks [8]. Finally, the moiré potential in asymmetric twisted bilayer graphene/hexagonal boron nitride heterostructures gives rise to robust electronic ratchet states. The resulting hysteretic, non-volatile injection of charge carriers enables room-temperature operation of moiré synaptic transistors with diverse bio-realistic neuromorphic functionalities and efficient compute-in-memory designs for low-power artificial intelligence and machine learning hardware [9].[1] V. K. Sangwan, et al., Matter, 5, 4133 (2022).[2] V. K. Sangwan, et al., Nature Nanotechnology, 15, 517 (2020).[3] M. E. Beck, et al., ACS Nano, 14, 6498 (2020).[4] M. E. Beck, et al., Nature Communications, 11, 1565 (2020).[5] X. Yan, et al., Nature Electronics, DOI: 10.1038/s41928-023-01042-7 (2023).[6] X. Yan, et al., Advanced Materials, 34, 2108025 (2022).[7] H.-S. Lee, et al., Advanced Functional Materials, 30, 2003683 (2020).[8] J. Yuan, et al., Nano Letters, 21, 6432 (2021).[9] X. Yan, et al., Nature, DOI: 10.1038/s41586-023-06791-1 (2023).

Giant Carrier Mobility in a Room-Temperature Ferromagnetic VSi2N4 Monolayer.

Using density functional theory (DFT), we investigate that two possible phases of VSi2N4 (VSN) may be realized, one called the "H phase" corresponding to what is known from calculation and herein the other new "T phase" being stabilized by a biaxial tensile strain of 3%. Significantly, the H phase is predicted to display a giant carrier mobility of 1 × 106 cm2 V-1 s-1, which exceeds that for most 2D magnetic materials, with a Curie temperature (TC) exceeding room temperature and a band gap of 2.01 eV at the K point. Following the H-T phase transition, the direct band gap shifts to the Γ point and increases to 2.59 eV. The Monte Carlo (MC) simulations also indicate that TC of the T phase VSN can be effectively modulated by strain, reaching room temperature under a biaxial strain of -4%. These results show that VSN should be a promising functional material for future nanoelectronics.

A New Method for Analysis of Martials Nano and Micro Electronics Technologies

This final qualifying work investigates prospective microelectronic and nano electronic materials. The purpose of the final qualifying mission is to evaluate potential manufacturing technologies and materials. In the first phase of the endeavor, potential materials for microelectronics and nanoelectronics were investigated. Graphene, fullerenes, fullerites, carbon nanotubes (CNT), nanofibers, ferrites, barium hexaferrite, nano powders, and epitaxial coatings are among these substances. An investigation into diverse methodologies pertaining to the production of auspicious materials was undertaken during the preliminary stage of the undertaking. Molecular beam epitaxy, pulsed laser deposition, spray deposition, physical vapor deposition (PVD), chemical solution deposition, gas-phase synthesis, electrospinning, chemosynthesis, detonation synthesis and electric explosion, chemical vapor deposition (CVD), spray deposition, physical vapor deposition (PVD), and the sol-gel method were among these processes.

Electronic structure, magnetic and adsorption properties of monolayer chromium disulfide adsorbed by (non)-metals: A first-principles study

In this paper, the changes in the electronic structure, magnetic and adsorption properties induced by the adsorption of nine nonmetals (NMs) and twelve transition metals (TMs) on the monolayer CrS2 system have been investigated in the context based on the GGA+U methodology under the density-functional theory. The corresponding energetically most stable configurations were determined by calculating the formation energies for the four high-symmetry sites of each adsorption system. The atom adsorption induces a tunable electronic structure of the system, changing the surface structure and metallic properties of the monolayer CrS2. The system is made to show a wide variety of spintronic properties, such as narrow forbidden band semiconductors and semi-metals. Magnetically, the adsorbed atoms caused the redistribution of the electronic orbitals of the system, which formed local magnetic moments of different sizes at the adsorption sites and further caused the enhancement of the total magnetic moment of the system. The atom adsorption is expected to make monolayer CrS2 a potential spintronic material, which promotes the application of this material in nanoelectronics and spintronics.

Nonlinear charge and energy transport in anharmonic quasi-two-dimensional systems.

We study the localized states of an extra electron in an anisotropic quasi-two-dimensional system in which the electron-lattice interaction and the anharmonicity of the lattice vibrations are dominant in one direction. This model describes layers of polydiacetylene or other polymer chains, beta sheets of polypeptides, multilevel microstructures of conjugated polymers, and other low-dimensional systems. It is shown that for appropriate parameter values of the system an extra electron can excite a soliton-like mobile wave of the lattice deformation, within which it can get self-trapped. Such a bound state of an electron and the lattice deformation form a nonlinear two-component polaron-like entity, which can propagate with minimum of the energy dissipation. Our findings are based on the variational approach and the full numerical solution of the coupled system of nonlinear equations. These results suggest that the experimentally measured charge and energy transport over macroscopic distances in the above-mentioned systems can be provided by the soliton mechanism and thus have a potential impact on the theoretical background of the numerous applications of low-dimensional materials in nanoelectronics.

Tailoring Contacts for High-Performance 1D Ta2Pt3S8 Field-Effect Transistors.

Materials with van der Waals (vdW) unit structures rely on weak interunit vdW forces, facilitating physical separation and advancing nanomaterial research with remarkable electrical properties. Recently, there has been growing interest in one-dimensional (1D) vdW materials, celebrated for their advantageous properties, characterized by reduced dimensionality and the absence of dangling bonds. In this context, we synthesize Ta2Pt3S8, a 1D vdW material, and assess its suitability for field-effect transistor (FET) applications. Spectroscopic analysis and electrical characterization confirmed that the band gap and work function of Ta2Pt3S8 are 1.18 and 4.77 eV, respectively. Leveraging various electrode materials, we fabricated n-type FETs based on Ta2Pt3S8 and identified Cr as the optimal electrode, exhibiting a high mobility of 57 cm2 V-1 s-1. In addition, we analyzed the electron transport mechanism in n-type FETs by investigating Schottky barrier height, Schottky barrier tunneling width, and contact resistance. Furthermore, we successfully fabricated p-type operating Ta2Pt3S8 FETs using a molybdenum trioxide (MoO3) layer as a high work function contact electrode. Finally, we achieved Ta2Pt3S8 nanowire rectifying diodes by creating a p-n junction with asymmetric contact electrodes of Cr and MoO3, demonstrating an ideality factor of 1.06. These findings highlight the electronic properties of Ta2Pt3S8, positioning it as a promising 1D vdW material for future nanoelectronics and functional vdW-based device applications.

Molecular dynamics simulation-based study to analyse the properties of entrapped water between gold and graphene 2D interfaces.

Heterostructures based on graphene and other 2D materials have received significant attention in recent years. However, it is challenging to fabricate them with an ultra-clean interface due to unwanted foreign molecules, which usually get introduced during their transfer to a desired substrate. Clean nanofabrication is critical for the utilization of these materials in 2D nanoelectronics devices and circuits, and therefore, it is important to understand the influence of the "non-ideal" interface. Inspired by the wet-transfer process of the CVD-grown graphene, herein, we present an atomistic simulation of the graphene-Au interface, where water molecules often get trapped during the transfer process. By using molecular dynamics (MD) simulations, we investigated the structural variations of the trapped water and the traction-separation curve derived from the graphene-Au interface at 300 K. We observed the formation of an ice-like structure with square-ice patterns when the thickness of the water film was <5 Å. This could cause undesirable strain in the graphene layer and hence affect the performance of devices developed from it. We also observed that at higher thicknesses the water film is predominantly present in the liquid state. The traction separation curve showed that the adhesion of graphene is better in the presence of an ice-like structure. This study explains the behaviour of water confined at the nanoscale region and advances our understanding of the graphene-Au interface in 2D nanoelectronics devices and circuits.

Sublimation-based wafer-scale monolayer WS2 formation via self-limited thinning of few-layer WS2.

Atomically-thin monolayer WS2 is a promising channel material for next-generation Moore's nanoelectronics owing to its high theoretical room temperature electron mobility and immunity to short channel effect. The high photoluminescence (PL) quantum yield of the monolayer WS2 also makes it highly promising for future high-performance optoelectronics. However, the difficulty in strictly growing monolayer WS2, due to its non-self-limiting growth mechanism, may hinder its industrial development because of the uncontrollable growth kinetics in attaining the high uniformity in thickness and property on the wafer-scale. In this study, we report a scalable process to achieve a 4 inch wafer-scale fully-covered strictly monolayer WS2 by applying the in situ self-limited thinning of multilayer WS2 formed by sulfurization of WOx films. Through a pulsed supply of sulfur precursor vapor under a continuous H2 flow, the self-limited thinning process can effectively trim down the overgrown multilayer WS2 to the monolayer limit without damaging the remaining bottom WS2 monolayer. Density functional theory (DFT) calculations reveal that the self-limited thinning arises from the thermodynamic instability of the WS2 top layers as opposed to a stable bottom monolayer WS2 on sapphire above a vacuum sublimation temperature of WS2. The self-limited thinning approach overcomes the intrinsic limitation of conventional vapor-based growth methods in preventing the 2nd layer WS2 domain nucleation/growth. It also offers additional advantages, such as scalability, simplicity, and possibility for batch processing, thus opening up a new avenue to develop a manufacturing-viable growth technology for the preparation of a strictly-monolayer WS2 on the wafer-scale.

Silicon-Based Nanoelectronic Semiconductor Material and Its Surface-Enhanced Raman Image Signals

One-dimensional Zinc Oxide (ZnO) nanomaterials have important applications in devices, such as solar energy, sensors, and piezoelectric materials due to surface effects and quantum size effects. As a semiconductor material, Si has good thermal conductivity and low resistivity. A layer of n-type ZnO nanowires is grown on P-type monocrystalline silicon by transferring the Anodic Aluminum Oxide (AAO) template. The enhanced Raman effect on the surface is attempted by preparing n-type ZnO-P-type Si heterojunction nanostructures. This paper uses Si-based AAO as a template and uses electrochemical deposition method to prepare silicon-based nano-electronic semiconductor material ZnO/AAO/Si. According to SEM analysis, there are uniform pores on the surface of the material, and the cross-section shows that ZnO nanowires have been assembled into the AAO/Si structure. XRD analysis shows that ZnOn nanowires have a hexagonal wurtzite structure. In optoelectronic testing, through PL spectral analysis, the semiconductor material ZnO/AAO/Si has a strong yellow green emission peak near 574 nm. Field emission analysis shows that the β value of the ZnO field enhancement factor in the ZnO/AAO/Si structure is relatively high. The Surface-Enhanced Raman Spectroscopy (SERS) image signal experiment shows that the silicon-based nano-electronic semiconductor material prepared by electrochemical deposition method has good SERS characteristics. The SERS spectral intensity increases with the increase of the concentration of the detected substance and can be used as a SERS substrate to achieve Raman spectral image signal detection of chemical substances with low concentration.

Tuning the metal–semiconductor contact nature in MXene-based van der Waals heterostructures

Two-dimensional (2D) transition metal carbides, nitrides, or carbonitrides (MXenes) have emerged as promising ultrathin materials for nanoelectronics and optoelectronics. However, the contact barrier at metal–semiconductor (MS) junctions still significantly limits the device's performance. Here, we propose a novel strategy—functionalizing accompanied with external electric fields—to tune the MS contact nature in MXene-based van der Waals (vdW) heterostructures, taking 2D Ti2C as an example, by means of first-principles calculations. Different Ti2CO2/Ti2CX2 (X = OH or S) vdW heterostructures are designed via functionalizing Ti2C metals to contact with 2D Ti2CO2. We reveal that OH functionalized vdW MS heterostructure (Ti2CO2/Ti2C(OH)2) can be tuned to the Ohmic contact owing to the strong interlayer interaction inducing a large number of interlayer transferred electrons; while for the sulfurized vdW MS heterostructure (Ti2CO2/Ti2CS2), its Schottky barrier height and contact type can be effectively tuned by external electric field due to the rather weak interlayer interaction. Our work paves a new way for the construction of 2D MXene-based vdW MS heterostructures and demonstrates the great potential of 2D MXenes in future nanoelectronics and optoelectronics.

Application of Fluorescent Carbon Nanoelectronic Materials in Combining Partial Differential Equations for Fingerprint Development and Its Image Enhancement

Fluorescent developers play a crucial role when dealing with objects with complex patterns or color interference against their background due to their excellent photoluminescent properties. In recent years, fluorescent nanoelectronic materials have emerged as a novel class of fluorescent materials for fingerprint development research. Here, carbon quantum dots (CQDs) are synthesized using an electrochemical method and utilized as fluorescent nanoelectronic materials in combination with gold nanoparticles (AuNPs) to form a composite (Au/CQDs). The photoelectric properties of Au/CQDs are verified, and a precursor solution for Au/CQDs is prepared using the Wessling method. After the addition of a surfactant and subsequent elimination processes, an Au/CQDs fluorescent nanocolloidal solution is obtained. This solution is applied for the development of visible fingerprints and latent fingerprints on adhesive surfaces. The resulting development images are subjected to enhancement processes such as sharpening, smoothing, and noise reduction using partial differential equations to improve their visual quality. In experiments, under light exposure, Au/CQDs exhibit a higher conversion rate with cyclohexane compared to conditions without light. In the Au/NPs system, the fluorescence of CQDs is effectively quenched due to the rapid electron transfer process within the Au/CQDs system. Moreover, the electrode modified with Au/CQDs shows significantly improved efficiency in decomposing H2O2 compared to conditions without light exposure. After the development with Au/CQDs nanoparticle colloid solution, bright fingerprint patterns are visible under ultraviolet light. As the age of the fingerprint increases, the developed fingerprint has a higher resolution than fresh fingerprints. Image enhancement through partial differential equations results in satisfactory sharp edges and smooth contours in the images.

(Invited) Two-Dimensional Neuromorphic Computing Materials and Devices

The exponentially improving performance of digital computers has recently slowed due to the speed and power consumption issues resulting from the von Neumann bottleneck. In contrast, neuromorphic computing aims to circumvent these limitations by spatially co-locating logic and memory. Beyond reducing power consumption, neuromorphic devices provide efficient architectures for image recognition, machine learning, and artificial intelligence [1]. This talk will explore how two-dimensional (2D) nanoelectronic materials enable gate-tunable neuromorphic devices [2]. For example, by utilizing self-aligned, atomically thin heterojunctions, dual-gated Gaussian transistors have been realized, which show tunable anti-ambipolarity for artificial neurons, competitive learning, spiking circuits, and mixed-kernel support vector machines [3]. In addition, field-driven defect motion in polycrystalline monolayer MoS2 enables gate-tunable memristive phenomena that serve as the basis of hybrid memristor/transistor devices (i.e., 'memtransistors' [4]) that concurrently provide logic and data storage functions [5]. The planar geometry of memtransistors further allows multiple contacts and dual gating that mimic the behavior of biological systems such as heterosynaptic responses [6]. Moreover, control over polycrystalline grain structure enhances the tunability of potentiation and depression, which enables unsupervised continuous learning in spiking neural networks [7]. Overall, this work introduces foundational circuit elements for neuromorphic computing by utilizing the unique quantum characteristics of 2D nanoelectronic materials [8].[1] V. K. Sangwan, et al., Nature Nanotechnology, 15, 517 (2020).[2] M. E. Beck, et al., ACS Nano, 14, 6498 (2020).[3] M. E. Beck, et al., Nature Communications, 11, 1565 (2020).[4] V. K. Sangwan, et al., Nature, 554, 500 (2018).[5] X. Yan, et al., Advanced Materials, 34, 2108025 (2022).[6] H.-S. Lee, et al., Advanced Functional Materials, 30, 2003683 (2020).[7] J. Yuan, et al., Nano Letters, 21, 6432 (2021).[8] X. Liu, et al., Nature Reviews Materials, 4, 669 (2019).

Raman Characterization of Guanine Functionalized SWCNTs

Single-walled carbon nanotubes (SWCNTs) have unique photophysical properties that render them an important class of materials for future nanoelectronics and bio-nano sensor applications. A method was recently discovered for making spatially patterned modifications to SWCNT band gaps and thereby modulating their electronic and optical properties in a controlled manner. The reaction used for this is called guanine functionalization.1 It is achieved by generating singlet oxygen in a dispersion of SWCNTs coated with single-stranded DNA, resulting in covalent bond formation between the guanine nucleobases in the DNA coatings and the nanotube sidewalls. Each of the many covalently bonded guanine sites acts as a weak exciton trap, causing red-shifted SWCNT emission and absorption spectra. Fluorescence spectroscopy shows that the extent of guanine functionalization can depend strongly on SWCNT structure, but spectral broadening can hamper the precise deconvolution of emission features of different (n,m) species. To track such covalent functionalization through Raman scattering, the D to G band ratios are commonly used as a measure of sp3 defect density and therefore of the functionalization extent. However, this conventional Raman method cannot show which (n,m) species in unsorted samples have been functionalized, because they all contribute to the D and G band signals. We will describe a novel Raman analysis based on the relative intensities of bands that have shifts located between the RBM and D regions. These Raman features are found to be diameter-specific, allowing estimation of (n,m)-resolved functionalization extents in unsorted SWCNT samples. In addition, we will present an assignment and interpretation of the relevant Raman features. Zheng, Y.; Bachilo, S. M.; Weisman, R. B., Controlled patterning of carbon nanotube energy levels by covalent DNA functionalization. ACS Nano 2019, 13, 8222-8228.

Fermi-Level Engineering of Nitrogen Core-Doped Armchair Graphene Nanoribbons.

Substitutional heteroatom doping of bottom-up engineered 1D graphene nanoribbons (GNRs) is a versatile tool for realizing low-dimensional functional materials for nanoelectronics and sensing. Previous efforts have largely relied on replacing C-H groups lining the edges of GNRs with trigonal planar N atoms. This type of atomically precise doping, however, only results in a modest realignment of the valence band (VB) and conduction band (CB) energies. Here, we report the design, bottom-up synthesis, and spectroscopic characterization of nitrogen core-doped 5-atom-wide armchair GNRs (N2-5-AGNRs) that yield much greater energy-level shifting of the GNR electronic structure. Here, the substitution of C atoms with N atoms along the backbone of the GNR introduces a single surplus π-electron per dopant that populates the electronic states associated with previously unoccupied bands. First-principles DFT-LDA calculations confirm that a sizable shift in Fermi energy (∼1.0 eV) is accompanied by a broad reconfiguration of the band structure, including the opening of a new band gap and the transition from a direct to an indirect semiconducting band gap. Scanning tunneling spectroscopy (STS) lift-off charge transport experiments corroborate the theoretical results and reveal the relationship among substitutional heteroatom doping, Fermi-level shifting, electronic band structure, and topological engineering for this new N-doped GNR.

Mirroring and reversible fine-tuning of the transport spin-polarization in PC3 nanoribbons based on an electrical method

The electrical approach is favored over the conventional magnetic approach for its low energy consumption and continuously variable control of spin polarization. Inspired by the recently reported PC3 monolayer, we investigate its spin-dependent electron transmission characteristics through the first-principles calculations. The results show that the transmission peaks with opposite spin directions at the Fermi level have precisely opposite responses to the gate voltage, which leads to the system being able to alter between spin-polarized and unpolarized states, and as well as achieving any ratio between − 100 % and 100 % for spin-up and spin-down electrons. Notably, this regulation is also reversible and mirror-symmetric. Further research demonstrates that the crux lies in the particular transmission peak contributed by the edge sp2-hybridized C atoms. This study sheds new light on the potential of PC3 as a novel nanoelectronic material for spintronics applications, suggesting that it can be used to create bipolar spin filters with tunable filtering effects.

Multilayer Graphene-Coated Silicon Carbide Nanowire Formation Under Defocused Laser Irradiation

Graphene-coated silicon carbide (SiC@C) core–shell nanostructures have attracted attention in the fields of energy storage and nanoelectronics. In this study, multilayer graphene-coated silicon carbide (SiC) nanowires were obtained through the laser irradiation of a mixture target of graphite powder and silicon (Si) grinding sludge discharged from Si wafer manufacturing. Laser irradiation was performed using an ytterbium (Yb) fiber pulsed laser with a pulse width of 10 ms and a wavelength of 1070 nm with various defocus distances. The effect of laser defocusing on the morphology of the generated nanostructures was investigated. Results showed that nanowires were produced under the defocused conditions, and nanoparticles were observed at the on-focus position. The products obtained under all defocused conditions showed a core–shell structure, and the SiC nanowires were covered by graphene layers. The aspect ratio of the nanowires increased with the defocus distance. Observation of the laser-induced plume using a high-speed camera showed that when the laser was defocused, the plume propagation speed slowed down, and the shape of the plume changed to a swirling vortex. The nanowire formation was closely related to the propagation speed and shape variation of the plume. This successful production of SiC@C core–shell nanowires from Si waste opens up the possibility of the sustainable development of new materials for energy storage and nanoelectronics.

Formation of nanoribbons by carbon atoms confined in a single-walled carbon nanotube-A molecular dynamics study.

Carbon nanotubes can serve as one-dimensional nanoreactors for the in-tube synthesis of various nanostructures. Experimental observations have shown that chains, inner tubes, or nanoribbons can grow by the thermal decomposition of organic/organometallic molecules encapsulated in carbon nanotubes. The result of the process depends on the temperature, the diameter of the nanotube, and the type and amount of material introduced inside the tube. Nanoribbons are particularly promising materials for nanoelectronics. Motivated by recent experimental results observing the formation of carbon nanoribbons inside carbon nanotubes, molecular dynamics calculations were performed with the open source LAMMPS code to investigate the reactions between carbon atoms confined within a single-walled carbon nanotube. Our results show that the interatomic potentials behave differently in quasi-one-dimensional simulations of nanotube-confined space than in three-dimensional simulations. In particular, the Tersoff potential performs better than the widely used Reactive Force Field potential in describing the formation of carbon nanoribbons inside nanotubes. We also found a temperature window where the nanoribbons were formed with the fewest defects, i.e., with the largest flatness and the most hexagons, which is in agreement with the experimental temperature range.

Local strain engineering in Janus MoSSe nanoribbons induces tunable electronic structures and remarkable magnetic moments

Local strain, as a small degree and single direction strain method, can effectively regulate the structures and electronic properties of armchair Janus MoSSe nanoribbon, so that the system can be transformed from the original 0.467 eV indirect band gap into 0.259 eV (3-zig), 0.117 eV (3-arm), 0.080 eV (6-arm) and 0.139 eV (9-zig) direct band-gap semiconductor according to the different strain degrees and directions. Compared with traditional MoS2 and MoSe2 nanoribbons, Janus MoSSe nanoribbon shows relatively stable band structure under local strain. The structure and electronic properties of Janus MoSSe nanoribbon are anisotropic when the local strain is along different directions. Due to the broken mirror symmetry of the Janus system and the appearance of in-plane local polarization, the spin polarization effect of Janus nanoribbon under local strain is more remarkable. When the local strain degree C = 0.167 is along the zigzag direction and the local strain C ⩾ 0.056 is along the armchair direction, the Janus nanoribbon exhibits half-metallic properties and surprisingly induces a magnetic moment. For the local strain along the armchair direction, the total magnetic moment of the system can be up to 2.05 μB when C = 0.111. A local strain method is applied to the nanoribbon system, which can effectively regulate the geometric configuration and electronic structure without external doping, and introduce magnetism, providing the possibility for expanding nanoribbons as potential nanoelectronic and spintronic materials.