Nanoscale Semiconductor Research Articles

Spatially resolved random telegraph fluctuations of a single trap at the Si/SiO2 interface

We use electrostatic force microscopy to spatially resolve random telegraph noise at the Si/SiO2 interface. Our measurements demonstrate that two-state fluctuations are localized at interfacial traps, with bias-dependent rates and amplitudes. These two-level systems lead to correlated carrier number and mobility fluctuations with a range of characteristic timescales; taken together as an ensemble, they give rise to a [Formula: see text] power spectral trend. Such individual defect fluctuations at the Si/SiO2 interface impair the performance and reliability of nanoscale semiconductor devices and will be a significant source of noise in semiconductor-based quantum sensors and computers. The fluctuations measured here are associated with a four-fold competition of rates, including slow two-state switching on the order of seconds and, in one state, fast switching on the order of nanoseconds which is associated with energy loss.

Quantum imaging-based nanobiosensors: Pioneering point-of-care approach for early diagnosis of environmental-linked breast cancer

Early detection is paramount for successful treatment outcomes in cancer diagnosis. Among women across the globe, breast cancer (BC) ranks as one of the deadliest forms of cancer. Prolonged exposure to numerous environmental pollutants has been linked to epigenetic reprogramming, which entails changes in the expression patterns of non-coding RNAs. These alterations have been strongly linked to an increased risk of developing BC. Women are confronted with hazardous smoke from polluting stoves and fuels for longer as they often perform home duties such as cooking. Inefficient combustion emits black carbon (sooty particles), which enters the bloodstream and is strongly connected to an elevated risk of BC. The use of several analytical methods, such as real-time polymerase chain reaction, microarray, and sequencing, has numerous disadvantages, such as high expenses, limitations in sensitivity, and lack of accuracy. However, the emergence of quantum dots (QDs), nanoscale semiconductor particles with unique optical properties, and the development of quantum imaging-based sensors offer a glimpse into the future of medical technology. These sensors have the potential to completely change the medical field by offering highly precise, non-invasive, and reliable techniques for early diagnosis. Our article delves into the intricacies of QDs imaging-based sensors, their applications in BC detection, and their transformative impact on improving patient care. In recent years, the confluence of quantum science and diagnostic imaging has opened new avenues for BC diagnosis. The present state of quantum imaging-based BC diagnosis sensors is examined in this article, along with potential future developments with the help of artificial intelligence.

Optimization of electron transmission on a 1D lattice

Finding optimal multi-layer heterostructure configurations that result in desired current–voltage characteristics requires physical control of electron scattering processes. It is shown how a one-dimensional tight-binding Hamiltonian combined with the adjoint method may be employed to explore this non-convex and non-intuitive design space. Such optimal parameter exploration has application to study of vertical electron transport through van der Waals stacked few-layer quantum materials and nano-scale single-crystal semiconductor heterostructures.

Revealing the Role of Redox Reaction Selectivity and Mass Transfer in Current–Voltage Predictions for Ensembles of Photocatalysts

Photocatalysts are conceptually simple reaction units where nanoscale semiconductors integrated with catalysts drive a pair of redox reactions on illumination. However, the proximity of reaction sites performing cathodic and anodic reactions poses dire challenges to realize large light-to-fuel conversion efficiencies. In this study, a powerful, yet straightforward, equivalent-circuit detail-balance modeling framework is developed and applied to evaluate the performance of photocatalytic systems featuring multiple light absorbers. Specifically, low bandgap iridium-doped strontium titanate is modeled a Z-scheme photocatalyst to effect desired hydrogen evolution and iron-based redox shuttle oxidation reactions. Our model has unique capabilities to simulate competing redox reactions and address mass-transfer limitations. In a significant departure from state-of-the-art circuit models, our study develops tools to perform load-line analyses by incorporating a net electrochemical load curve that includes both desired and competing redox reactions. Consequently, reaction selectivity is predicted from equivalent circuit models for photocatalytic and photoelectrochemical systems. Our investigation into ensembles comprised of multiple, semi-transparent light absorbers reveals their potential to outperform a single, optically thick light absorber, particularly when operated under mass-transfer-limited conditions. However, this outcome hinges on minimizing mass-transfer rates of select redox species to prevent undesired reactions of hydrogen oxidation and/or redox shuttle reduction. Our findings demonstrate that reaction selectivity can be achieved by tuning asymmetry in redox species mass-transfer even with perfectly symmetric electrocatalytic charge-transfer coefficients. The influences of various kinetic, mass-transfer, and thermodynamic parameters are explored to offer crucial insights to inform the next-generation of photocatalysts, selective coatings, and reactor designs.

Measuring the Electronic Bandgap of Carbon Nanotube Networks in Non-Ideal p-n Diodes.

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.

Surface structure-based model to calculate thermal and optical properties in nanoscale and quantum dot semiconductors

Surface combination structure was used to design the construction of nano and quantum films, particles, and dots. The created model was applied to tetrahedral semiconductor nanoparticles and quantum dots with a successful performance. It works better than reported experimental data across the whole size range, from the bulk state to the critical size of quantum dots. The model helps to figure out the melting point that changes with the nanosize scale as applied on Si and Sn, which are simple tetrahedral semiconductors, and for CdS and CdSe, which are among II-VI group compounds. It was also used to calculate melting-related parameters such as cohesive energy, Debye temperature, vibrational entropy, and melting enthalpy. The nanosize dependence of the lattice volume and the atom's ionization energy describes the solid surface structure. From the model, an equation was obtained to calculate the energy gaps in Si, CdS, and CdSe particles that are nano- and quantum-dot-sized, and the results are compared to the experimental data that goes with these particles.

Recent Development and Advancement in Quantum Dots in Pharmaceutical and Biomedical Fields for the Delivery of Drugs

Abstract: Nanoscale semiconductors known as quantum dots (QDs) are essential for drug testing because they bridge the gap between nanotechnology and the testing of drugs. QDs are a valuable tool in theranostics and treatment because of their unique physicochemical features. Due to their photoluminescence and electronic properties, including broad and continuous absorption spectra, narrow emission spectra from visible to near-infrared wavelengths, and long-lasting and high brightness, they are suitable probe materials for use in (bio)sensing (immunological) platforms. Several studies use QDs due to their optical, magnetic, electrical, photochemical, and biological features that allow them to be employed in various scientific domains. When utilized in drug delivery systems, fluorescent markers, such as QDs, can track the metabolism of drugs in the human body. Many medicinal applications, such as disease diagnosis and medication research, can benefit from these fluorescent tests. In this review article, the application of QD in drug delivery and immunoassay sensing has been described in detail.

Onset of spin entanglement in doped carbon nanotubes studied by EPR.

Nanoscale semiconductors with isolated spin impurities have been touted as promising materials for their potential use at the intersection of quantum, spin, and information technologies. Electron paramagnetic resonance (EPR) studies of spins in semiconducting carbon nanotubes have overwhelmingly focused on spins more strongly localized by sp3-type lattice defects. However, the creation of such impurities is irreversible and requires specific reactions to generate them. Shallow charge impurities, on the other hand, are more readily and widely produced by simple redox chemistry, but have not yet been investigated for their spin properties. Here, we use EPR to study p-doped (6,5) semiconducting single-wall carbon nanotubes (s-SWNTs) and elucidate the role of impurity-impurity interactions in conjunction with exchange and correlation effects for the spin behavior of this material. A quantitative comparison of the EPR signals with phenomenological modeling combined with configuration interaction electronic structure calculations of impurity pairs shows that orbital overlap, combined with exchange and correlation effects, causes the EPR signal to disappear due to spin entanglement for doping levels corresponding to impurity spacings of 14nm (at 30K). This transition is predicted to shift to higher doping levels with increasing temperature and to lower levels with increasing screening, providing an opportunity for improved spin control in doped s-SWNTs.

Microwave characterization of nanomaterials using planar slot resonator

Nanomaterial characterization using microwaves is needed in nanoscale semiconductor devices, microwave imaging, EM shielding, and wireless communication. Many nanomaterials are used as metallic or dielectric layers in these applications. In this paper, we report the characterization of nanomaterials using planar Microwave Slot Resonator (MSR) which was designed and studied using 3D EM simulation tool. The response of MSR is parameterized which offers a platform to calculate relative permittivity (ε r) and conductivity (σ) from measured high frequency response of nanomaterial loaded MSR. With simplified method, this microwave characterization offers accurate and faster results which be used in design, calculation and numerical analysis of nanomaterial based electronic/optoelectronic devices and sensor/shielding applications.

Benchmarking of X-Ray Fluorescence Microscopy with Ion Beam Implanted Samples Showing Detection Sensitivity of Hundreds of Atoms.

Single impurities in insulators are now often used for quantum sensors and single photon sources, while nanoscale semiconductor doping features are being constructed for electrical contacts in quantum technology devices, implying that new methods for sensitive, non-destructive imaging of single- or few-atom structures are needed. X-ray fluorescence (XRF) can provide nanoscale imaging with chemical specificity, and features comprising as few as 100000 atoms have been detected without any need for specialized or destructive sample preparation. Presently, the ultimate limits of sensitivity of XRF are unknown - here, gallium dopants in silicon are investigated using a high brilliance, synchrotron source collimated to a small spot. It is demonstrated that with a single-pixel integration time of 1 s, the sensitivity is sufficient to identify a single isolated feature of only 3000Ga impurities (a mass of just 350 zg). With increased integration (25 s), 650 impurities can be detected. The results are quantified using a calibration sample consisting of precisely controlled numbers of implanted atoms in nanometer-sized structures. The results show that such features can now be mapped quantitatively when calibration samples are used, and suggest that, in the near future, planned upgrades to XRF facilities might achieve single-atom sensitivity.

A nonlocal photoacoustic effect with variable thermal conductivity of semiconductor material subjected to laser heat source

This study explores the behavior of laser-exposed photo-excited carriers, investigating the propagation of photoacoustic waves in the thermoelastic domain. It also delves into the theoretical generation of surface acoustic waves in semiconductors through photo-thermoelastic processes. The research considers the interaction between thermomechanical and acoustic waves in a nonlocal medium with temperature-dependent thermal conductivity. Unlike relying on electron–phonon or electron-hole thermalization processes, photoacoustic waves here result from thermoelastic stress induced by the laser-induced temperature increase. The investigation accounts for the optical, mechanical, and thermoelastic properties of nanoscale semiconductor materials. Predictions of photoacoustic signals are derived by solving a combined thermal diffusion issue and a thermoelastic problem, using Laplace and Fourier transforms in the mathematical model. Numerical solutions encompass various physical fields within the time domain using the inversion technique of Laplace and Fourier transforms, such as thermal, acoustic, mechanical, and carrier density diffusion. The study evaluates and compares the influences of thermal memory and thermal conductivity presenting visual representations.

Biomimetic nanocluster photoreceptors for adaptative circular polarization vision

Nanoclusters with atomically precise structures and discrete energy levels are considered as nanoscale semiconductors for artificial intelligence. However, nanocluster electronic engineering and optoelectronic behavior have remained obscure and unexplored. Hence, we create nanocluster photoreceptors inspired by mantis shrimp visual systems to satisfy the needs of compact but multi-task vision hardware and explore the photo-induced electronic transport. Wafer-scale arrayed photoreceptors are constructed by a nanocluster-conjugated molecule heterostructure. Nanoclusters perform as an in-sensor charge reservoir to tune the conductance levels of artificial photoreceptors by a light valve mechanism. A ligand-assisted charge transfer process takes place at nanocluster interface and it features an integration of spectral-dependent visual adaptation and circular polarization recognition. This approach is further employed for developing concisely structured, multi-task, and compact artificial visual systems and provides valuable guidelines for nanocluster neuromorphic devices.

Editorial

Represent the Organizing Committee of The 1st International Conference on Applied Physics and Mathematics (ICAPM2023). The conference was a great success providing appropriate platform to researchers, scholars and industry practitioners to share their work and experience on the Changsha, China in different sectors.In today’s era, the research and development of Applied Physics can be considered very valuable, it also has been a buzzword in recent times majorly in last few years. Almost every research and scholar is getting involved in this context to derive significant and tangible gains to the benefit of the society as a whole.And as we know, Applied Physics is generally considered to be composite because it contains several cross cutting core disciplines, such as Semiconductor Physics, Nanoscale physics, Electronics Design & Manufacturing and GIS/GPS Systems, etc. The basic concepts and technologies of these disciplines have been combined to form the basis of Applied Physics. These technologies can help people generate important insights to support further decisions. However, the application of Applied Physics is very challenging, which leads to the diversity of its development. Since the past few decades, Applied Physics has been one of the most interesting fields. It has recently become an inevitable part of our daily life by adding technology to solve practical problems.The 1st International Conference on Applied Physics and Mathematics (ICAPM2023) focuses on works that have been done for development of new technology or enhancement of the existing ones to make them applicable in diverse range of sectors and corresponding problems. We have received a good number of responses of around 65 papers from researchers, scholars and industry practitioners covering a wide range of application areas.According to their quality, degree of conformity with our topics and other indicators, we finally received 23 articles.We hope this proceeding will provide valuable insights and serve for new scholars interested to explore Applied physics, Application of applied physics and Mathmatics in various sectors.Editor:Xilong QuList of Committees are available in this Pdf.

Influence of the Schottky Junction on the Propagation Characteristics of Shear Horizontal Waves in a Piezoelectric Semiconductor Semi-Infinite Medium

In this paper, a theoretical model of the propagation of a shear horizontal wave in a piezoelectric semiconductor semi-infinite medium is established using the optimized spectral method. First, the basic equations of the piezoelectric semiconductor semi-infinite medium are derived with the consideration of biased electric fields. Then, considering the propagation of a shear horizontal wave in the piezoelectric semiconductor semi-infinite medium, two equivalent mathematical models are established. In the first mathematical model, the Schottky junction is theoretically treated as an electrically imperfect interface, and an interface characteristic length is utilized to describe the interface effect of the Schottky junction. To legitimately confirm the interface characteristic length, a second mathematical model is established, in which the Schottky junction is theoretically treated as an electrical gradient layer. Finally, the dispersion and attenuation curves of shear horizontal waves are numerically calculated using these two mathematical models to discuss the influence of the Schottky junction on the dispersion and attenuation characteristics of shear horizontal waves. Utilizing the equivalence of these two mathematical models and the above numerical results, the numerical value of the interface characteristic length is reliably legitimately confirmed; this value is independent of the thickness of the upper metal layer, the doping concentration of the lower n-type piezoelectric semiconductor substrate, and biasing electric fields. Only the biasing electric field parallel to the Schottky junction can provide an evident influence on the attenuation characteristics of shear horizontal waves and enhance the interface effect of the Schottky junction. Since the second mathematical model is also a validation of our previous mathematical model established through the state transfer equation method, some numerical results calculated using these two mathematical models are compared with those obtained using the previous method to verify the correctness and superiority of the research work presented in this paper. Since these two mathematical models can better calculate the dispersion and attenuation curves of high-frequency waves in micro- and nano-scale piezoelectric semiconductor materials, the establishment of mathematical models and the revelation of physical mechanisms are fundamental to the analysis and optimization of micro-scale resonators, energy harvesters, and amplifications.

Carbon-TiO2 Hybrid Quantum Dots for Photocatalytic Inactivation of Gram-Positive and Gram-Negative Bacteria.

Carbon-semiconductor hybrid quantum dots are classical carbon dots with core carbon nanoparticles doped with a selected nanoscale semiconductor. Specifically, on those with the nanoscale TiO2 doping, denoted as CTiO2-Dots, their synthesis and thorough characterization were reported previously. In this work, the CTiO2-Dots were evaluated for their visible light-activated antibacterial function, with the results showing the effective killing of not only Gram-positive but also the generally more resistant Gram-negative bacteria. The hybrid dots are clearly more potent antibacterial agents than their neat carbon dot counterparts. Mechanistically, the higher antibacterial performance of the CTiO2-Dots is attributed to their superior photoexcited state properties, which are reflected by the observed much brighter fluorescence emissions. Also considered and discussed is the possibility of additional contributions to the antibacterial activities due to the photosensitization of the nanoscale TiO2 by its doped core carbon nanoparticles.

Quasi-Zero-Dimensional Ferroelectric Polarization Charges-Coupled Resistance Switching with High-Current Density in Ultrascaled Semiconductors.

Ferroelectric memristors hold immense promise for advanced memory and neuromorphic computing. However, they face limitations due to low readout current density in conventional designs with low-conductive ferroelectric channels, especially at the nanoscale. Here, we report a ferroelectric-mediated memristor utilizing a 2D MoS2 nanoribbon channel with an ultrascaled cross-sectional area of <1000 nm2, defined by a ferroelectric BaTiO3 nanoribbon stacked on top. Strikingly, the Schottky barrier at the MoS2 contact can be effectively tuned by the charge transfers coupled with quasi-zero-dimensional polarization charges formed at the two ends of the nanoribbon, which results in distinctive resistance switching accompanied by multiple negative differential resistance showing the high-current density of >104 A/cm2. The associated space charges in BaTiO3 are minimized to ∼3.7% of the polarization charges, preserving nonvolatile polarization. This achievement establishes ferroelectric-mediated nanoscale semiconductor memristors with high readout current density as promising candidates for memory and highly energy-efficient in-memory computing applications.

A novel model of nonlocal photoacoustic and plasmaelastic heated by laser pulsed excitation of nanoscale semiconductor medium

The study takes into account the diffusion of photo-excited carriers in the presence of a laser pulse and theoretically investigates photoacoustic wave propagation in the thermoelastic domain. In a nonlocality medium, the phenomena of thermomechanical and acoustic wave interaction are considered. Thermoelasticity, photothermal, and photoacoustic theories provide the controlling formulas. Photoacoustic waves are not dependent on electron–phonon or electron–hole thermalization processes; rather, they are produced by thermoelastic stress resulting from the temperature increase induced by the laser. The optical, elastic, and thermoelastic characteristics of nanoscale semiconductor materials are taken into account and photoacoustic signals are predicted by solving a thermal diffusion issue and a thermoelastic problem in combination. The mathematical model can be solved using the harmonic wave approach. By obtaining numerical solutions, all the physical fields of the physical domain, such as thermal, acoustic, mechanical, and carrier density diffusion, as well as displacements and temperatures, can be derived. The influences of nonlocal parameters, thermal delay, and laser pulse effect are investigated and compared using two- and three-dimensional visual representations, corresponding to two-dimensions and three-dimensions domains, respectively.

Atomic Layer Etching of SiO2 for Nanoscale Semiconductor Devices: A Review

Atomic Layer Etching of SiO₂ for Nanoscale Semiconductor Devices: A Review

The quantum revolution in vehicle sensor technology

AbstractWith technology like lidar heralding a revolution in vehicle automation, SWIR (short‐wave infrared) imaging and sensing will become increasingly vital to the automotive sector. Quantum dots, nanoscale semiconductors tunable to SWIR wavelengths, could provide the answer to empowering SWIR and bringing enhanced capability to the mass market.

Bandgap formation in graphene doped with BN, TiO2, Al2O3 and ZnO by sintering process

Nanoelectronics emphasises graphene and bandgap opening, where a larger band gap is helpful for different electronic applications. Here, we report on the larger bandgap opening and tuneable bandgap in graphene doped with BN, TiO2, Al2O3 and ZnO by the novel sintering process. In this study, the electronic band structure of graphene is studied systematically in the presence of doping by UV–vis spectroscopy; studies revealed a bandgap formation in graphene. For the first time, a significant and larger bandgap as high as 2.65 eV is observed for graphene-95 % TiO2-3 % BN-2 % combination, and the TiO2 doping and isoelectronic BN opened the π π* band gap of graphene. The quantum confinement effect confined the holes and electrons in the nanoscale semiconductors. As a result, the semiconductor’s band gap increases the energy difference between the empty and filled states. The experimental results are varified by a theoretical approach called machine learning. The current findings open the door to creating graphene-based devices doped with BN, TiO2, Al2O3, and ZnO tailored for band gaps.