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Device noise reduction for silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate
摘要： The sensitivity of metal-oxide-semiconductor field-effect transistor (MOSFET) based nanoscale sensors is ultimately limited by noise induced by carrier trapping/detrapping processes at the gate oxide/semiconductor interfaces. We have designed a Schottky junction gated silicon nanowire field-effect transistor (SiNW-SJGFET) sensor, where the Schottky junction replaces the noisy oxide/semiconductor interface. Our sensor exhibits significantly reduced device noise, 2.1×10-9 V2μm2/Hz at 1 Hz, compared to reference devices with the oxide/semiconductor interface operated at both inversion and depletion modes. Further improvement can be anticipated by wrapping the nanowire by such a Schottky junction thereby eliminating all oxide/semiconductor interfaces. Hence, a combination of the low-noise SiNW-SJGFET device with a sensing surface of the Nernstian response limit holds promises for future high signal-to-noise ratio sensor applications.
关键词： Noise reduction,field-effect transistor,ion sensor,low frequency noise,schottky junction gate,silicon nanowire
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Austin, TX, USA (2018.9.24-2018.9.26)] 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - The Impact of Dopant Diffusion on Random Dopant Fluctuation in Si Nanowire FETs: A Quantum Transport Study
摘要： In this work, we perform statistical quantum transport simulations with 3×3 nm2 Si nanowire (NW) field-effect transistors (FETs) to investigate the impact of dopant diffusion on random dopant fluctuation. First, we use an effective mass Hamiltonian for the transport where the confinement and transport effective masses are extracted from the tight-binding band structure calculations. The dopant diffusion along the transport direction from the source/drain regions to the channel region is modeled by the Gaussian doping profile. To generate random discrete dopants, we adopt a rejection scheme considering the 3-dimensional atomic arrangement of the NW structures. Our statistical simulation results show that the diffused dopants into the channel region cause large variability problems in Si NW FETs.
关键词： non-equilibrium Green's function,tight-binding,dopant diffusion,random discrete dopants,silicon nanowire
更新于2025-09-23 15:22:29
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Characterization of the Piezoresistive Effects of Silicon Nanowires
摘要： Silicon nanowires (SiNWs) have received attention in recent years due to their anomalous piezoresistive (PZR) effects. Although the PZR effects of SiNWs have been extensively researched, they are still not fully understood. Herein, we develop a new model of the PZR effects of SiNWs to characterize the PZR effects. First, the resistance of SiNW is modeled based on the surface charge density. The characteristics of SiNW, such as surface charge and effective conducting area, can be estimated by using this resistance model. Then, PZR effects are modeled based on stress concentration and piezopinch effects. Stress concentration as a function of the physical geometry of SiNWs can amplify PZR effects by an order of magnitude. The piezopinch effects can also result in increased PZR effects that are at least two times greater than that of bulk silicon. Experimental results show that the proposed model can predict the PZR effects of SiNWs accurately.
关键词： nonlinearity,silicon nanowire,surface depletion effects,piezoresistive effects
更新于2025-09-23 15:21:21
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Effects of vacancy defects location on thermal conductivity of silicon nanowire: a molecular dynamics study
摘要： The improvement of thermoelectric ?gure of merit of silicon nanowire (SiNW) can be achieved by lowering its thermal conductivity. In this work, non-equilibrium molecular dynamics method was used to demonstrate that the thermal conductivity of bulk silicon crystal is drastically reduced when it is crafted as SiNW and that it can be reduced remarkably by including vacancy defects. It has been found that ‘centre vacancy defect’ contributes much more in reducing the thermal conductance than ‘surface vacancy defect’. The lowest thermal conductivity that occurs is about 52.1% of that of pristine SiNW, when 2% vacancy defect is introduced in the nanowire. The vibrational density of states analysis was performed to understand the nature of this reduction and it has been found that the various boundary scatterings of phonon signi?cantly reduce the thermal conductivity. Also, larger mass difference due to voids induces smaller thermal conductivity values. These results indicate that the inclusion of vacancy defects can enhance the thermoelectric performance of SiNWs.
关键词： molecular dynamics,silicon nanowire,thermoelectric performance,thermal conductivity,vacancy defects
更新于2025-09-23 15:21:21
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ALD of ZnO:Ti: Growth Mechanism and Application as an Efficient Transparent Conductive Oxide in Silicon Nanowire Solar Cells
摘要： In the quest for replacement of indium-tin-oxide (ITO), Ti-doped zinc oxide (TZO) films have been synthesized by atomic layer deposition (ALD) and applied as n-type transparent conductive oxide (TCO). TZO thin films were obtained from titanium (IV) i-propoxide (TTIP), diethyl zinc and water, by introducing TiO2 growth cycle in a ZnO matrix. Process parameters such as the order of precursor introduction, the cycle ratio and the film thickness were optimized. The as-deposited films were analyzed for their surface morphology, elemental stoichiometry, optoelectronic properties and crystallinity, using a variety of characterization techniques. The growth mechanism was investigated for the first time by in situ quartz-crystal microbalance measurements. It evidenced different insertion modes of titanium depending on the precursor introduction, as well as the etching of Zn-Et surface groups by TTIP. Resistivity as low as 1.2 × 10-3 Ω cm and transmittance > 80% in the visible range were obtained for 72-nm thick films. Finally, the first application of ALD-TZO as TCO was reported. TZO films were successfully implemented as top electrodes in silicon nanowire solar cells. The unique properties of TZO combined with conformal coverage realized by ALD technique make it possible for the cell to show almost flat EQE response, surpassing the bell-like EQE curve seen in devices with sputtered ITO top electrode.
关键词： TCO,silicon nanowire solar cells,n-type,ZnO:Ti,Atomic Layer Deposition,QCM studies
更新于2025-09-23 15:19:57
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Wafer-scale HfO<sub>2</sub> encapsulated silicon nanowire field effect transistor for efficient label-free DNA hybridization detection in dry environment
摘要： Silicon nanowire (SiNW) charge based biosensors are attractive for DNA sensing applications due to their compactness and large surface-to-volume ratio. Small feature size, low production cost, repeatability, high sensitivity and selectivity are some of the key requirements for biosensors. The most common e-beam manufacturing method employed to manufacture sub-nm SiNWs is both cost and time intensive. Therefore, we propose a highly reproducible CMOS industry grade low-cost process to fabricate SiNW based field effect transistors on 4”-wafers. The 60 nm wide SiNWs reported in this paper are fabricated using the sidewall transfer lithography process which is a self-aligned-double-patterning I-line lithography process that also facilitates encapsulation of the SiNW surface with a thin HfO2 layer on which DNA probes are grafted to finalize the biosensors. Upon DNA hybridization, SiNW devices exhibit threshold voltage shift larger than the noise introduced by the exposition to saline solutions used for the bioprocesses. More specifically, based on a statistical analysis, we demonstrate that 85% of the tested devices exhibit a positive threshold voltage shift after DNA hybridization. These promising results make way for the monolithic integration of SiNW biosensors and CMOS circuitry to realize a point of care device which can offer reliable real time electrical readout.
关键词： HfO2 passivation,silicon nanowire hybridization,silicon nanowire,DNA sensing,pattern transfer lithography,biosensor
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Performance and Degradation Evaluation of PV Modules on the Substring Level by an In-Situ Electronic Device
摘要： We report silicon ?eld emitter arrays (FEAs) that demonstrate current densities >100 A/cm2 at gate–emitter voltages <75 V. These are the highest current densities reported for a semiconductor FEA, and approach the current densities of Spindt-type metal cathodes. We achieved these results using a new device structure that employs high-aspect-ratio silicon nanowire current limiters in series with each emitter tip to address the major failure mechanisms in FEAs. These current limiters mitigate emitter tip failure due to joule heating thus allowing for higher reliability. We employed a novel fabrication process to produce small gate apertures (≈350 nm) that are self-aligned to the ?eld emitter tip enabling device operation at >100 A/cm2 with gate-to-emitter voltages that are less than 75 V. These FEAs demonstrate performance that has the potential to enable smaller, more ef?cient, and high-power vacuum electronics.
关键词： FEAs,nanowires,Field emission arrays,silicon FEAs,silicon tips,silicon nanowire current limiters
更新于2025-09-19 17:13:59
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Electrostatically Doped Silicon Nanowire Arrays for Multispectral Photodetectors
摘要： Nanowires have promising applications as photodetectors with superior ability to tune absorption with morphology. Despite their high optical absorption, the quantum efficiencies of these nanowire photodetectors remain low due to difficulties in fabricating a shallow junction using traditional doping methods. As an alternative, we report non-conventional radial heterojunction photodiodes obtained by conformal coating of indium oxide layer on silicon nanowire arrays. The indium oxide layer has a high work function which induces a strong inversion in the silicon nanowire and creates a virtual p-n junction. The resulting nanowire photodetectors show efficient carrier separation and collection leading to an improvement of quantum efficiency up to 0.2. In addition, by controlling the nanowire radii, the spectral response of the In2O3/Si nanowire photodetectors are tuned over several visible light wavelengths, creating a multispectral detector. Our approach is promising for the development of highly-efficient wavelength selective photodetectors.
关键词： electrostatic doping,nanowire photodetectors,multispectral,photosensors,silicon nanowire,dopant-free,radial junction
更新于2025-09-16 10:30:52
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Dispersion tailoring of silicon nanowire optical rectangular waveguide (SNORW)
摘要： Dispersion analysis on silicon nanowire optical rectangular waveguide (SNORW) has been presented in this paper by guiding light inside low refractive index region. Dispersion engineering is an essential study to utilize any photonic integrated circuit-based waveguide in linear and nonlinear optical devices. This paper exhibits distinctive dispersion characteristics recognized in the wavelengths of S, C and L bands by tailoring physical parameters of SNORW. Modal investigation and numerical analysis have been carried out by finite element method (FEM), which shows that SNORW configuration enables the flat and low negative dispersion behavior. This paper also demonstrates the utilization of cladding materials and structural parameters of SNORW to tune the magnitude and behavior of dispersion for flat dispersion profile.
关键词： Silicon nanowire,Photonic integrated circuits,Optical waveguide,Dispersion,Silicon photonics,Photonic structure,Nanophotonics
更新于2025-09-16 10:30:52
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Low reflecting hierarchically textured silicon by silver assisted chemical etching for potential solar cell application
摘要： Present study reports fabrication of silicon nanowires over micro-textured Si substrates. Silver assisted electroless chemical etching route has been adopted for fabrication of the nanowires. Influence of HF concentration on the formation kinetics has been investigated by using scanning electron microscopy. The hierarchical binary structures have been able to reduce solar weighted reflectance (SWR) to <3% in broad spectral range (300-1100 nm), from 38% SWR of the polished silicon without any additional coating. Such reduction in reflectivity is obtained for <1 μm nanowires length. It is observed that at relatively lower concentration of HF the nanowires are preferably formed only in <100> direction. However, with increase in the concentration, etching in both <100> and non-<100> directions such as <111> also occurs on the micro-pyramids of similar dimensions and results in the binary structures with slanted silicon nanowires on 3-dimansional micro-pyramids.
关键词： Nanowire,Micro-pyramid,Chemical Etching,Reflectance,Silicon Nanowire
更新于2025-09-12 10:27:22