Micro and Nanostructures最新文献

In order to solve the electrical performance limitations of horizontal multilayer graphene nanoribbon (H-MLGNR) based interconnect, a new geometric structure of vertical multilayer graphene nanoribbon (V-MLGNR) based interconnect is proposed in this paper. A numerical model for H-MLGNR and V-MLGNR based interconnects is established to investigate the performance in time and frequency domain, where the high-k dielectric materials (HKDM) are introduced for improving their transmission performance. The computation results demonstrate that the delay time for H-MLGNR and V-MLGNR based interconnects with embedded BaTiO₃–Ni case can be reduced over 89.601 % and 93.723 % in comparison to the original H-MLGNR and V-MLGNR based interconnects, respectively. The corresponding 3-dB bandwidth for them can be expanded over 1.928 and 2.957 times, respectively. Moreover, it is manifested that the delay time of V-MLGNR based interconnect for the original, embedding the HfO₂, TiO₂, SrTiO₃, BaTiO₃, 6.0 vol% BaTiO₃–Ni and 12.0 vol% BaTiO₃–Ni cases can be reduced over 11.644 %, 13.269 %, 16.851 %, 22.311 %, 27.589 %, 33.608 % and 46.556 % as compared with the conventional H-MLGNR based interconnect, respectively. Meanwhile the corresponding 3-dB bandwidth of the former for the original, embedding the HfO₂, TiO₂, SrTiO₃, BaTiO₃, 6.0 vol% BaTiO₃–Ni and 12.0 vol% BaTiO₃–Ni cases can be enhanced over 1.113, 1.126, 1.155, 1.207, 1.266, 1.366 and 1.737 times as compared with the latter, respectively. In addition, the signal integrity of the proposed V-MLGNR based interconnects with embedded HKDM is greater than H-MLGNR based interconnects, while the power consumption of the former is slightly higher than the latter. Therefore, the proposed new interconnect structure concerning the V-MLGNR with embedded HKDM would be rewarding to enhance transmission performance of interconnect system in VLIS circuits.

For the first time, we reported the noise and sensitivity analysis of the Dielectric Modulated Reconfigurable Silicon Nanowire-based Schottky Barrier Transistor (DMR SiNW-SBT) for biosensor applications. To validate the simulation, we present experimental calibration of the DMR SiNW-SBT biosensor. The biomolecules having different dielectric constants and charge densities are immobilized in the cavity region under the control gate. These biomolecules modulate the Schottky junction width at the source channel interface and enhance the drain current of the biosensor. The simulation results indicate that the proposed device I_ON and V_TH sensitivity improved by 54.65 % and 85.71 %, respectively, with the state-of-the-art biosensors. Noise analysis shows that the NF_min decreased by 190.32 % and offers a low source impedance of 70Ω, which minimizes signal loss and distortion. Additionally, we investigate the linearity parameters that outperformed the FET-based biosensors. The gm3 experiences a reduction of 123.21 %, while the VIP3 sees an increase of 7.87 % and the IIP3 shows a rise of 7.21 %. Furthermore, we have conducted device optimization by varying the cavity length and thickness. We also outline potential fabrication steps for the DMR SiNW-SBT biosensor. Thus, results show that the proposed biosensor emerges as a promising candidate for advanced biosensing applications with high sensitivity, enhanced linearity, and robust noise resilience.

In the present era, FET devices are seamlessly integrated with complex circuits that can be used to realize chips capable of operating at a significantly higher speed. These designed devices can meet the requisite of circuits used in designing mobile phones, tablets and laptops, thereby enhancing the overall performance. The present work focuses on designing of gate stack inverted-T junctionless FET at 20 nm technology node. Both static and low frequency characteristics of device such as threshold voltage ($V_{Th}$), transconductance ($g_m$), on ($I_{ON}$) & off ($I_{OFF}$) state currents, as well as its high-frequency characteristics like total gate capacitance ($C_{gg}$), cut-off frequency ($f_T$), maximum oscillation frequency $\left(f_{\max }\right)$ and gain bandwidth product (GBW) are methodically demonstrated with alterations in the device process and geometrical variations. The parameters such as height of fin, width of fin and work function are varied to study their impact. The SS, DIBL, $I_{ON}/I_{OFF}$ (current switching ratio) and $V_{Th}$, for 20 nm gate length are observed as 67.94 mV/dec, 34.32 mV/V, 10⁸, 0.32 V, respectively. The $f_{\max }$ is determined to be in the THz range and has early voltage of approximately 6.12V. Additionally, the effect of temperature is also studied by varying it in the range of 250 K–450 K. Analysis and virtual modelling of device is carried out using Visual TCAD. In addition, p-channel transistor is designed along with the n-channel configuration to investigate the device performance for CMOS based circuits. The noise margin and average delay of the inverter circuit are observed to be 0.37 V and 36.7 ps respectively.

Ga₂O₃ is an ultrawide-band-gap semiconductor with excellent properties and promising applications in the electronic and optoelectronics. For acting as the substrate for heteroepitaxial Ga₂O₃ films, Si has the advantages of wafer-level size, cheap price and nice compatibility whereas also perform the disadvantage of large thermal mismatch. In this paper, the apparent flower-like defects are exhibited on the macroscopic surfaces of annealed Ga₂O₃ films deposited on (100), (110) and (111) oriented Si substrates by atomic layer deposition (ALD) method. The reason is ascribed to the different thermal expansion coefficients between Ga₂O₃ and Si induced compressive and tensile stresses. The Al₂O₃ or HfO₂ buffer layer intercalated between Ga₂O₃ films and Si substrates via successive ALD process suppress the flower-like defects effectively while the surface roughnesses are low to be 1.290 nm and 2.393 nm, respectively. XRD spectra demonstrate that buffer layer indeed relieves the stress of Ga₂O₃ films on Si substrates while the amorphous Al₂O₃ has better influence than the polycrystalline HfO₂. The results are helpful to the improvement of growth quality and device property of Ga₂O₃.

A mid-infrared (mid-IR) chiral absorber based on multilayer films of silicon (Si)/Weyl semimetal (WSM)/Si is proposed and numerically studied. The proposal exhibits high quality factor circular dichroism (CD) with different absorptance properties for right-hand circular polarization (RCP) and left-hand circular polarization (LCP) light. The absorption characteristics have been explored with the generalized 4 × 4 transfer matrix algorithm, and the effects of structural parameters on the circularly polarized (CP) absorptance are systematically investigated. The circular polarization efficiency (η) and CD are defined as crucial parameters for quantifying the chirality response. The results prove that the chiral absorber exhibits extraordinary efficiencies of 1 and 0 for LCP and RCP light at a wavelength of 11.5 μm, respectively. Thus a maximum CD in absorption of unity with a resonant quality factor (Q-factor) of 295 can be obtained. The performance of dual-band chiral responses can be engineered via the thickness of each layer. Moreover, it is identified that the design results in angle-independent performance, which is essential trait for an efficient chiral absorber.

Heavy metal pollution on air, water, and soil is an issue of increasing global concern. Adsorption is widely recognized as one of the most effective methods for removing heavy metal pollution. The adsorption mechanisms of As (Arsenic), Pb (Lead), and Zn (Zinc) atoms on thermally activated palygorskite Si–O (200) and Mg–O (200) surfaces were investigated using first-principles calculations based on DFT. The coverage dependence of the adsorption configurations and energies on the most stable adsorption sites was also analyzed. The bridge site was found to be the most stable adsorption site for As and Pb on the Si–O (200) surface, while the adsorption energy of Zn was ＜ 0.1 eV on the surface. The adsorption capacity order of the surface was As > Pb ≫ Zn. On the Mg–O (200) surface, the hollow site was the most stable site for three heavy metal atoms. The adsorption energies of them gradually decreased with increasing coverage, thus indicating the lower stability of surface adsorption due to the repulsion of neighboring heavy metal atoms. The adsorption capacity of the Mg–O (200) surface followed the order of As > Pb > Zn. Further exploration was performed on the changes in structure and electronic properties within the adsorption process by studying the lattice relaxation, Bader charge, and electronic density of states (DOS) of the thermally activated palygorskite (200)/heavy metal atoms system.

This paper employs first-principles methods to compute the stability, electrical properties, and optical properties of the GaN/Sc₂CF₂ heterostructure and investigates its photoelectric effect by constructing a photodetector device. The GaN/Sc₂CF₂ heterostructure has been found to be an indirect bandgap semiconductor with a bandgap value of 1.836 eV, and its substantial stability has been determined through phonon spectrum and molecular dynamics calculations. A charge transfer occurs in the GaN/Sc₂CF₂ heterostructure, resulting in the formation of an internal electric field directed from the Sc₂CF₂ layer to the GaN layer. Compared to single-layer GaN and Sc₂CF₂, the GaN/Sc₂CF₂ heterostructure has a wider absorption spectrum and enhanced light absorption in the visible light range. For the GaN/Sc₂CF₂ photodetector, it exhibits high photocurrent and extinction ratio, demonstrating favorable photoresponse characteristics, and it is more sensitive to changes in the polarization angle along the armchair direction. This research provides theoretical basis and research ideas for the photogalvanic detection capability of GaN/Sc₂CF₂ van der Waals heterostructures, offering a promising candidate material for photodetectors.

Hierarchical Au-decorated SnO₂ (Au@SnO₂) microflowers with a porous structure were successfully synthesized. The preparation process involves in a hydrothermal method, calcination treatment, as well as modification. The hierarchical structure consisted of a large number of porous, uniform nanosheets. Excellent gas-sensing performances were demonstrated by the gas sensors fabricated using Au@SnO₂ microflowers, for detecting volatile organic compounds (VOCs). In particular, for the accurate and fast detection of formaldehyde, the 2%Au-decorated SnO₂ microflowers sensors showed a strong sensing response (76.5) for formaldehyde (100 ppm) at 140 °C, approximately three times higher than that (28.2) observed for the pure porous SnO₂ microflowers. The response and recovery times (10 s/16 s) were shorter than those (12 s/25 s) of the pure SnO₂, respectively. The detection limit for the 2%Au@SnO₂ sensor was 19.03 ppb. The sensing mechanism of Au@SnO₂ sensors was also investigated. Favorable porous 3-dimensional structure, high catalytic activity, and electron sensitization effect of Au nanoparticles (NPs) improved the gas-sensing performance. Furthermore, the catalytic activity of Au NPs was maximized due to their uniform distribution on the surface of each porous SnO₂ nanosheet. The Au-decorated SnO₂ microflowers sensors have great potential for the accurate, fast, and highly sensitive response detection of formaldehyde gas.

People pay more and more attention to sports and health, especially the goal of sports recovery and scientific sports is more and more clear. In order to avoid human injury caused by unreasonable sports, it is necessary to carry out real-time detection of human motion state. In this paper, the motion state of human body was taken as the test object, a flexible strain sensitive material combining iron nanowires and carbon microspheres was proposed, and polyester fabric was introduced as the sensor substrate to construct a sandwich structure flexible fabric strain sensor. Then a mechanical test platform was built to carry out mechanical property testing and practical application verification research. The mechanical test results show that the iron nanowires/carbon microspheres flexible fabric strain sensor has good linearity, the response time is 42 ms, and the hysteresis error is approximately 8.7 %. Finally, the flexible fabric strain sensor is fixed on the part of the human body that needs to be detected, and the electrical signal curve of the response is output by the electrochemical workstation. Through the analysis of the response curve, it can be seen that the iron nanowires/carbon microspheres flexible fabric strain sensor prepared in this paper has great potential in human movement health monitoring.

AlN/GaN superlattices are studied using the empirical tight-binding method (ETBM) with sp³ approximation. The model includes first-nearest-neighbor orbital interactions and accounts for the strain effect by modifying the ETBM parameters based on variations in bond lengths and angles. According to the authors knowledge, this study marks the first application of ETBM to determine the full band structure of AlN/GaN superlattices. On average, the ETBM band gaps resulting from this work are 7.48 % closer to the experimental data in comparison with Kronig-Penney outputs. In addition to the high accuracy of the model, the presented model is easier to implement compared to the density functional theory model.