Search Results (237)

This study investigates the influence of rotation on wave propagation in a semiconducting nanostructure thermoelastic solid subjected to a ramp-type heat source within a two-temperature model. The thermoelastic interactions are modeled using the two-temperature theory, which distinguishes between conductive and thermodynamic temperatures, providing a more accurate description of thermal and mechanical responses in semiconductor materials. The effects of rotation, ramp-type heating, and semiconductor properties on elastic wave propagation are analyzed theoretically. Governing equations are formulated and solved analytically, with numerical simulations illustrating the variations in thermal and elastic wave behavior. The key findings highlight the significant impact of rotation, nonlocal parameters $e_{0}a$, and time derivative fractional order (FO) $\alpha$ on physical quantities, offering insights into the thermoelastic performance of semiconductor nanostructures under dynamic thermal loads. A comparison is made with the previous results to show the impact of the external parameters on the propagation phenomenon. The numerical results show that increasing the rotation rate $\mathsf{\Omega }=5$ causes a phase lag of approximately 22% in thermal and elastic wave peaks. When the thermoelectric coupling parameter ${\mathsf{\epsilon }}_3$ is increased from $-0.8\times {10}^{-42}$ to $1.2\times {10}^{-42}$. The temperature amplitude rises by 17%, while the carrier density peak increases by over 25%. For nonlocal parameter values $\mathsf{\epsilon }=0.3\to 0.6$, high-frequency stress oscillations are damped by more than 35%. The results contribute to the understanding of wave propagation in advanced semiconductor materials, with potential applications in microelectronics, optoelectronics, and nanoscale thermal management. Full article

Since the definitions of the two-dimensional (2D) optical absorption coefficient and photoconductivity are independent of the thickness of 2D materials, they are more suitable than the dielectric function to describe the optical properties of 2D materials. Based on the many-body GW method and the Bethe–Salpeter equation, we calculated the quasiparticle electronic structure, optical absorbance, and complex photoconductivity of 2D InSe from a single layer (1L) to three layers (3L). The calculation results show that the energy difference between the direct and indirect band gaps in 1L, 2L, and 3L InSe is so small that strain can readily tune its electronic structure. The 2D optical absorbance results calculated taking into account exciton effects show that light absorption increases rapidly near the band gap. Strain modulation of 1L InSe shows that it transforms from an indirect bandgap semiconductor to a direct bandgap semiconductor in the biaxial compressive strain range of −1.66 to −3.60%. The biaxial compressive strain causes a slight blueshift in the energy positions of the first and second absorption peaks in monolayer InSe while inducing a measurable redshift in the energy positions of the third and fourth absorption peaks. Full article

Researchers conduct experiments to discover factors influencing the experimental subjects, so the experimental design is essential. The response surface methodology (RSM) is a special experimental design used to evaluate factors significantly affecting a process and determine the optimal conditions for different factors. The relationship between response values and influencing factors is mainly established using regression analysis techniques. These equations are then used to generate contour and surface response plots to provide researchers with further insights. The impact of regression techniques on response surface methodology (RSM) model building has not been studied in detail. This study uses complete regression techniques to analyze sixteen datasets from the literature on semiconductor manufacturing, steel materials, and nanomaterials. Whether each variable significantly affected the response value was assessed using backward elimination and a t-test. The complete regression techniques used in this study included considering the significant influencing variables of the model, testing for normality and constant variance, using predictive performance criteria, and examining influential data points. The results of this study revealed some problems with model building in RSM studies in the literature from three engineering fields, including the direct use of complete equations without statistical testing, deletion of variables with p-values above a preset value without further examination, existence of non-normality and non-constant variance conditions of the dataset without testing, and presence of some influential data points without examination. Researchers should strengthen training in regression techniques to enhance the RSM model-building process. Full article

As power electronics continue to advance, the demand for highly efficient and low-loss DC/DC converters has grown significantly. This article comprehensively analyses ZCS quasi-resonant switch cell losses and efficiency in buck L-type zero-current switching (ZCS) quasi-resonant DC/DC converters. The main part of the study includes a comparative analysis of conduction losses in semiconductor switches of conventional PWM buck converters and zero-current switching (ZCS) quasi-resonant buck converters (L-type), utilizing both specific and generalized design equations. Novel coefficients are introduced that enable the evaluation of static power losses in the classical buck converter compared to those in L-type ZCS buck quasi-resonant converters under identical conditions. The article also discusses design considerations aimed at minimizing static losses. An L-type half-mode zero-current switching (ZCS) buck quasi-resonant DC/DC converter (QRC) is implemented to verify the analytical results. Various simulations were conducted using PSpice in the Texas Instruments simulation environment, along with experimental studies at different switching frequencies and load conditions. The proposed methodology integrates both analytical and simulation approaches to analyze energy losses and key parameters influencing the converter’s efficiency. The obtained results show that the relative error between the analytical, simulation, and experimental results is below 5%. Full article

The quantum efficiency $(QE)$ or gain $(G)$ of a photoconductive device is most commonly given in the literature as a ratio of carrier lifetime to transit time, allowing for a value much greater than unity. In this work, by assuming primary photoconductivity, we reexamine the photoconductive theory for the device with an intrinsic (undoped) semiconductor, with nearly zero equilibrium carrier densities. Analytic gain formula is obtained for arbitrary drift and diffusion parameters under a bias voltage and by neglecting the polarization effect due to the relative displacement in the electron and hole distributions. We find that the lifetime/transit-time ratio formula is only valid in the limit of weak field and no diffusion. Numerical simulations are performed to examine the polarization effect, confirming that it does not change the qualitative conclusions. We discuss the distinction between two $QE$ definitions used in the literature: accumulative $QE$ $\left({QE}_{acc}\right)$, considering the contributions of the flow of all photocarriers, regardless of whether they reach the electrode; and apparent $QE$ (${QE}_{app})$, measuring the photocurrent at the electrode. In general, ${QE}_{acc}>{QE}_{app}$, due to an inhomogeneous photocurrent in the channel; however, both approach the same unity limit for strong drift. We find that ${QE}_{acc} \ne { QE}_{app}$ is a deficiency of the commonly adopted constant-carrier-lifetime approximation in the recombination terms. Full article

It is experimentally established that there is no ground triplet state of the natural $He$ atom. There is also no exact analytical solution to the Schrödinger equation corresponding to this state. For a two-dimensional two-electron ‘artificial atom’ or a semiconductor quantum dot in a magnetic field, as described by the Schrödinger–Pauli equation, we provide theoretical proof of the existence of a ground triplet state by deriving an exact analytical correlated wave function solution to the equation. The state exists in the Wigner high-electron-correlation regime. We further explain that the solution satisfies all requisite symmetry and electron coalescence constraints of a triplet state. Since, due to technological advances, such a Wigner crystal quantum dot can be created, we propose an experimental search for the theoretically predicted ground triplet-state spectral line. We note that there exists an analytical solution to the Schrödinger–Pauli equation for a ground singlet state in the Wigner regime for the same value of the magnetic field. The significance to quantum mechanics of the probable experimental observation of the ground triplet state for an ‘artificial atom’ is discussed. Full article

Laser annealing plays a significant role in the fabrication of scaled-down semiconductor devices by activating dopant ions and rearranging silicon atoms in ion-implanted silicon wafers, thereby improving material properties. Precise temperature control is crucial in wafer annealing, particularly for repeated processes where repeatability affects uniformity. In this study, we employ a three-dimensional time-dependent thermal simulation model to numerically analyze the multiple static laser annealing processes based on a CO₂ laser with a center wavelength of 9.3 μm and a pulse repetition rate of 10 kHz. The heat transfer equation is solved using a multiphysics coupling approach to accurately simulate the effects of different numbers of CO₂ laser pulses on wafer temperature rise and repeatability. Additionally, a pyrometer is used to collect and convert the surface temperature of the wafer. Radiation intensity is converted to temperature via Planck’s law for real-time monitoring. Post-processing is performed to fit the measured temperature and the actual temperature into a linear relationship, aiding in obtaining the actual temperature under small beam spots. According to the simulation conditions, a wafer annealing device using a CO₂ laser as the light source was independently built for verification, and a stable and uniform annealing effect was realized. Full article

This study theoretically investigates the impact of comb spacing irregularity on the dynamics of optically injected semiconductor lasers using a rate equation model. Bifurcation analysis, time-domain simulations, spectral properties, and Mode Suppression Ratio (MSR) calculations reveal that equal spacing induces strong mode competition and chaos, while unequal spacing suppresses chaos and enhances stability. Interestingly, the Flipped comb exhibits similar behavior to the unequal comb, further supporting the conclusion that relative spacing—not spectral order—governs stability the Arbitrary combs, though lacking structured spacing, demonstrate intermediate suppression, indicating that breaking uniformity mitigates instability, but optimal spacing maximizes stabilization. Extending beyond previous studies on frequency comb injection, this work identifies spacing irregularity as a key mechanism for chaos control, offering new strategies for laser stabilization in optical communications and photonic integration. Full article

Despite extensive research on semiconductor materials, the influence of temperature and magnetic field on the optical quantum transitions within semiconductors remains insufficiently understood. We therefore investigated the Optical Quantum Transition Line Properties (OQTLP), including line shapes (LS) and line widths (LW), as functions of temperature and magnetic field in electron–piezoelectric-phonon-interacting systems within semiconductor materials. A theoretical framework incorporating projection-based equations and equilibrium average projection was applied to GaAs and CdS. Similarly, LW generally increases with magnetic field in a square-well confinement potential across most temperature regions. However, in high magnetic fields at low temperatures, LW decreases for GaAs. Additionally, LW increases with rising temperature. We also compare the LW and LS for transitions within intra- and inter-Landau levels to analyze the quantum transition process. The results indicate that intra-Landau level transitions primarily dominate the temperature dependence of quantum transitions in GaAs and CdS. Full article

With the advancement of the semiconductor industry into the sub-10 nm regime, high-performance, low-energy transistors have become important, and gate-all-around junctionless field-effect transistors (GAA-JLFETs) have been developed to meet the demands. Silicon (Si) is still the dominant semiconductor material, but other potential alternatives, such as gallium arsenide (GaAs), provide much higher electron mobility, improving the drive current and switching speed. In this study, our contributions include a comparative analysis of Si and GaAs-based cylindrical GAA-JLFETs, using threshold voltage behavior, electrostatic control, short channel effects, subthreshold slope, drain-induced barrier lowering, and leakage current as the metrics for performance evaluation. A comprehensive analytical modeling approach is employed, solving Poisson’s equation and utilizing numerical simulations to assess device characteristics using the ATLAS SILVACO tool under varying channel lengths and gate biases. Comparisons between Si and GaAs-based devices show what trade-offs exist and what the material engineering strategies are to use the advantages of GaAs while minimizing some disadvantages. The results of the study are a valuable contribution to the design and optimization of next-generation FET architectures, pointing the direction for enabling next-generation beyond CMOS technology. Full article

Including an n-doped layer in asymmetric double quantum wells restricts confined carriers into V-shaped potential profiles, forming discrete conduction subbands and enabling intersubband transitions. Most studies on doped semiconductor heterostructures focus on how external fields and structural parameters dictate optical absorption. However, electromagnetically induced transparency remains largely unexplored. Here, we show that the effect of an n-doped layer GaAs/Al_xGa_1−xAs in an asymmetric double quantum well system is quite sensitive to the width and position of the doped layer. By self-consistently solving the Poisson and Schrödinger’s equations, we determine the electronic structure using the finite element method within the effective mass approximation. We found that the characteristics of the n-doped layer can modulate the resonance frequencies involved in the electromagnetically induced transparency phenomenon. Our results demonstrate that an n-doped layer can control the electromagnetically induced transparency effect, potentially enhancing its applications in optoelectronic devices. Full article

This research is on the structural, optical, and electrical properties of SnO₂ and ZnO thin films, which are increasingly used in many electronic devices, including gas sensors, light-emitting diodes, and solar cells. For the various applications, it is essential to accurately determine the band gap energy, as it controls the optical and electrical behavior of the material. However, there is no single method for its determination; rather, different approximations depend on the crystalline quality and the doping level because these modify the energy band structure of the semiconductor. With the aim of analyzing the various approaches, SnO₂ and ZnO films were prepared by sputtering on unheated glass substrates and subsequently annealed in N₂ at various temperatures between 250 °C and 450 °C. These samples showed different crystallite sizes, absorption coefficients, and free carrier concentrations depending on the material and the annealing temperature. Analysis of the results shows that the expression developed for amorphous materials underestimates the band gap value, and the so-called unified method tends to overestimate it, while the equations for perfect or heavily doped crystals give band gap energies more consistent with the doping level, regardless of the crystalline quality of the films. Full article

The operating temperature can significantly affect the output voltage of high-temperature piezoresistive pressure sensors, presenting challenges to the measurement precision due to the intrinsic properties of semiconductor materials. This study developed a passive resistor network temperature compensation technique, utilizing differential equations to determine the compensation resistance parameters. Unlike conventional empirical algorithms, this method eliminated the need to account for variations among piezoresistors and addressed issues such as residual stress and mismatched coefficients of thermal expansion arising during manufacturing. The differential equation was simplified to derive the solution, and the calibration data were utilized to calculate the compensation resistance parameters, effectively compensating for the high-temperature piezoresistive pressure sensor. The results indicated that the passive resistance network successfully reduced the temperature drift, outperforming the traditional empirical algorithms. Full article

Rapid thermal annealing (RTA) has been widely used in semiconductor device processing. However, the rise time of RTA, limited to the millisecond (ms) range, is unsuitable for advanced nanometer-scale electronic devices. Using sub-energy bandgap (E_G) 532 nm ultra-fast 15 nanosecond (ns) pulsed laser annealing, a record-high dielectric constant (high-κ) of 67.8 and a capacitance density of 75 fF/μm² at −0.2 V were achieved in Ni/ZrO₂/TiN capacitors. According to heat source and diffusion equations, the surface temperature of TiN can reach as high as 870 °C at a laser energy density of 16.2 J/cm², effectively annealing the ZrO₂ material. These record-breaking results are enabled by a novel annealing method—the surface plasma effect generated on the TiN metal. This is because the 2.3 eV (532 nm) pulsed laser energy is significantly lower than the 5.0–5.8 eV energy bandgap (E_G) of ZrO₂, making it unabsorbable by the ZrO₂ dielectric. X-ray diffraction analysis reveals that the large κ value and capacitance density are attributed to the enhanced crystallinity of the cubic-phase ZrO₂, which is improved through laser annealing. This advancement is critical for monolithic three-dimensional device integration in the backend of advanced integrated circuits. Full article

The Bogomolny approach to the Ginzburg–Landau equations in the context of strong and semi-strong necessary conditions is formulated for various superconducting structures in a quasi-one-dimensional description, considering both flat and curved geometries. This formulation is justified by a perturbative approach to the Ginzburg–Landau theory applied to a superconducting structure that is polarized by an electric charge moving across two neighboring quantum dots. The situation considered involves an interface between a Josephson junction and a semiconductor quantum dot system in a one-dimensional setting. Full article