Micro and Nanostructures最新文献

In this work, Artificial Neural Network (ANN) algorithm is used to predict the current conduction mechanisms into the metal-semiconductor (MS) and metal-nanocomposite-semiconductor (MPS) structures along with their primary electronic parameters, such as the leak current (I₀), potential barrier height (Φ_B0), ideality factor (n), series/shunt resistance (R_s/R_sh), rectifying ratio (RR), and interface states density (N_ss) by analyzing the I–V characteristics. The polyvinylpyrrolidone (PVP), barium titanate (BaTiO₃) and graphene (Gr) nanoparticles are mixed together to create the interfacial nanocomposite layer. Training data for ANN algorithm is gathered using the thermionic emission hypothesis. In order to study the efficacy of the ANN model, the predictive power of the ANN technique for predicting the current conduction mechanisms and electronic properties of SDs has been assessed by comparing the predicted and experimental results. The ANN predictions of the current conduction mechanisms at the forward/reverse bias and the fundamental electronic specifications of the MS and MPS structures are a high level of agreement with the experimental results. Furthermore, the results show that the RR and R_sh rise whereas the n, R_s, and N_ss for MS structure decrease when the PVP:Gr-BaTiO₃ nanocomposite interlayer is employed.

This paper investigates the electrical and opto-sensing analysis of hetero stack vertical TFETs based on III/V group Gallium antimonide (GaSb)-Si at various wavelengths within the visible spectrum. Initially, the drain current, energy band diagram, and electron density contour plot are extracted in order to study the DC and electrical behavior of the device. Following that, their performance is evaluated by altering the source side thickness and observe the tunneling rate of device. Furthermore, the photo application of the device is noticed by computing the critical optical parameter such as sensitivity (Sn), noise factor, and efficient characteristics. Finally, a comparative table is included to set the benchmark and highlight the importance of hetero stack TFET. The device's maximum reported sensitivity is approximately 25.2 and responsivity (R) is 0.8 A/Watt at 320 nm wavelength. Additionally, we examined the effect of trap charges under light state at the gate-channel, isolator-channel, and source-channel interface respectively.

Square-shaped BiFeO₃ (BFO) thin films were prepared on SrTiO₃ (STO) substrates by off-axis magnetron sputtering using La_0.5Sr_0.5CoO₃ (LSCO) as the bottom electrode, and both LSCO and BFO are perovskite structure. The BFO crystalline quality improves and the grain size becomes larger as the thickness H increases, and both have smaller mean square roughness. The effects of BFO thickness H, light intensity I_p and ambient temperature AT on the ferroelectric photovoltaic effect (FPE) for the Pt/BFO/LSCO heterostructures are significant. With the H increase, the open-circuit voltage V_oc and short-circuit current J_sc increase linearly, with V_oc up to 0.44 V. The short-circuit current modulation intensity ΔJ_sc follows the ΔJ_sc-300>ΔJ_sc-200>ΔJ_sc-100 rule. With the I_p increase, Pt/BFO(300 nm)/LSCO’ J_sc increases linearly, and V_oc first increases and then tends to saturation, which satisfies Glass' law. With the AT increases, V_oc is linearly decreasing and J_sc shows the law: decreasing→increasing→decreasing. The polarization-modulated FPE mechanism is investigated by analyzing the Pt/BFO/LSCO energy band structure, which is attributed to the coupling effect between the BFO depolarization field (E_dp) and the built-in electric field at the interface (E_Pt/BFO & E_BFO/LSCO), and the FPE mechanism is shifted from the interface barrier domination to the ferroelectric polarization domination as H increases.

Microelectromechanical systems (MEMS) that utilize graphene-based materials have gained significant attention for gas-sensing applications owing to their unique properties. Graphene is a two-dimensional sheet of carbon atoms arranged in a hexagonal lattice that exhibits exceptional mechanical strength, high electrical conductivity, and large surface area. These properties make graphene an ideal candidate for gas sensing applications. In this study, we examined the fundamental characteristics of graphene, with emphasis on its practical use in sensors. We explored the latest techniques for synthesizing graphene, highlighting the importance of continual advancements in these manufacturing processes which are crucial for bringing graphene-based products to the market. We present various examples of how graphene is employed in MEMS for mass/gas sensing applications and discuss the advantages and challenges associated with devices using these materials. For successful incorporation of these materials into MEMS systems, it is essential to establish effective designs and integration processes that yield high results. Additionally, this analysis delves into the latest developments in graphene-based solid-state and movable MEMS devices, highlighting their promising gas-sensing applications.

In this work, we propose a promising source engineered Double - Gate (DG) Tunnel Field Effect Transistor (TFET) device capable of providing remarkably low value of Subthreshold Swing (SS) with sufficiently high drive current. Using Sentaurus TCAD simulations, we demonstrate that counter-doped horizontal pockets (doping of pocket is kept opposite to that of source) when placed in the source region introduces a built-in band bending at the source-pocket junction. This lowers the minima of Conduction Band (CB) in pocket region thereby reducing the barrier width as the pocket CB moves closer to source Valence Band (VB). As a result, stronger electric field is observed thereby reducing the threshold voltage (onset of band-to-band tunneling (BTBT)) and subsequent reduction in subthreshold swing. To boost the ON-current and suppress ambipolarity, high-k dielectric material along with low work-function gate material is introduced at source side and low-k gate dielectric along with high work-function gate material is introduced at drain side. Compared to point tunneling in conventional TFETs, the gate overlapped pockets in the proposed structure result in an increase in cross-section area available for BTBT thereby leading to line tunneling of carriers from the source to the pocket, resulting in higher ON-current. In this work, we discuss the role of source engineering in boosting the performance of Hetero-Dielectric (HD) Dual-Metal-Double-Gate (DMDG) TFET. We provide design guidelines to achieve steeper subthreshold swing while considering pocket doping and pocket thickness as the key parameters. A comparative study of conventional DG-TFET and HD-DG-TFET with the proposed Gate-over-Pockets (GoP) HD-DMDG-TFET structure is done. When compared to the conventional DG-TFET with same geometrical parameters, the proposed structure provides $\sim 33\times$ steeper SS, more than two order improved ON-current, two order lower ambipolar current and 133 folds better I_on/I_off thus becomes the perfect choice for low power applications.

The discovery of effective photocatalytic substances is crucial in reducing energy shortages and ecological contamination. This research involves creating SiC/PtSe₂ van der Waals heterostructure with both SiC and PtSe₂ monolayers, employing first-principles calculations for comprehensive theoretical analysis of their structural stability, electronic characteristics, optical features, Bader charge, and solar-to-hydrogen (STH) efficiency. Findings indicate that the SiC/PtSe₂ heterostructure is a semiconductor with an indirect bandgap of 1.52 eV and a direct Z-scheme charge transfer path, facilitating more efficient segregation of photogenerated electron-hole pairs. The Bader charge indicates that the SiC layer accumulates positive charges and the PtSe₂ layer accumulates negative charges, constituting a built-in electric field pointing from the SiC side to the PtSe₂ side at the interface region, which can impede the complexation of the photogenerated electron-hole pairs. Furthermore, the SiC/PtSe₂ heterostructure exhibits excellent optical absorption properties across both the ultraviolet and visible spectra, coupled with an exceptionally high STH efficiency of 34.7 %, significantly enhancing solar energy utilization. Ultimately, the Gibbs free energy calculations reveal the significant catalytic efficiency of the SiC/PtSe₂ heterostructure for redox reactions. Based on these results, the SiC/PtSe₂ heterostructure is a direct Z-scheme photocatalyst for overall water splitting.

Nanoscale phase change films of (MoTe₂)_xSb_1-x were prepared using magnetron sputtering technique. The investigation focused on the influence of the presence of MoTe₂ on the phase change characteristics of Sb materials as well as the electrical properties of devices. (MoTe₂)_xSb_1-x phase change films showed good thermal stability, especially for (MoTe₂)_0.08Sb_0.92 films. (MoTe₂)_xSb_1-x films had higher phase change temperature (∼185 °C), larger crystallization activation energy (∼4.0 eV), smaller resistance drift index (∼0.03582), and wider band gap (0.629 eV) than pure Sb films, indicating better thermal stability. According to X-Ray Diffraction and Atomic Force Microscope, it could be found that doping MoTe₂ in Sb could inhibit the grain growth and make the surface of Sb film flatter. According to the outcomes stemming from X-ray photoelectron spectroscopy, some bonds involving Mo–Te and Sb–Sb underwent breakage and actively contributed to the formation process of other chemical bonds at the interface. The formation of small Sb₂Te₃ and Sb grains in the as-deposited state played a role in inducing crystallization and accelerating phase transition. The band gap in (MoTe₂)_xSb_1-x films augmented with the increase of MoTe₂ content. The power consumption of the (MoTe₂)_0.08Sb_0.92-based phase-change memory device was considerably reduced compared to GST film and could achieve ultra-fast resistance transition within 10 ns. The results showed that (MoTe₂)_xSb_1-x phase change films have the advantages of high stability, low power consumption, and rapid speed, which is a potential choice for phase change memory.

In this study, we utilize Nextnano device simulation software to systematically investigate the dependence of 2-DEG (two-dimensional electron gas) density on the barrier and spacer Layers in InAlN/GaN high electron mobility transistors (HEMTs). By simulating a range of barrier thicknesses, In mole fractions, and spacer layer thicknesses, we reveal the intricate ways in which these parameters influence device performance. Our simulations demonstrate that precise control of the InAlN barrier thickness and In mole fraction, along with the AlN spacer thickness, is crucial for optimizing 2DEG density and, consequently, the overall electrical properties of the HEMTs. Notably, our results highlight that an InAlN barrier thickness below 12 nm, coupled with an optimized In mole fraction and a finely tuned AlN spacer thickness close to 1 nm, significantly enhances 2DEG density without compromising mobility. These insights provide a detailed understanding of the material and structural dependencies critical for the design and development of high-performance InAlN/GaN HEMTs. Our study includes detailed calculations of the device's I–V characteristics. Notably, the highest peak output current is observed at a 1 nm AlN spacer thickness, reaching 0.91 A/mm. Our findings highlight a noteworthy agreement between the results derived from our computational simulations and experimental measurements.

A double hexagonal single ‘S’ metamaterial (DHSSM), exhibiting plasmon-induced transparency (PIT) in its spectral response is studied in this paper. Amplitude modulation of the PIT window is achieved by varying the azimuth angle of substructure ‘S’. Theoretical investigations into the PIT effect are conducted through numerical simulations. Moreover, an equivalent coupling circuit and Lorentz model are constructed to elucidate the PIT modulation mechanism. The results reveal that the PIT physical mechanism of the DHSSM has originated in destructive interference between bright-bright modes, which is directly excited by terahertz waves on the double hexagonal split rings and the ‘S’ substructure. For slow optical propagation performance, the structure has a high group delay (up to 41.92 ps) while allowing for the adjustment of the transparency window amplitude. The proposed metamaterial holds promising prospects for applications in slow light devices, switches, and filters within the terahertz frequency range.

Based on the effective mass approximation and the compact density matrix theory, the electronic states and optical absorption properties of intersubband transitions between the conduction-band energy levels in zinc blende InGaN/GaN/InGaN/GaN core-shell quantum dots (CSQDs) are investigated by using the finite difference method. The effects of hydrogen-like impurity and In component on the wave functions, transition energies, and optical absorption properties are discussed in detail. The results show that hydrogen-like impurity can cause the peak positions of optical absorption coefficients (OACs) and refractive index changes (RICs) to move to high energy area, and the peak values of OACs rise. Increasing In component of InGaN crystal in the core region of a CSQD has the same effect. But an opposite tendency will be found when increasing In component in the shell-well of a CSQD, i.e. optical absorption peaks move to low energy area and their values decrease. Comparing to the shell-well, the core region has more powerful confinement effect on electrons. So the better absorption properties are more likely to be obtained for this type of multi-layer InGaN/GaN CSQDs when In component in the core is larger than that in the shell-well.