- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2018
- computer statistical experiment
- statistical optimization
- resonant-tunneling diode
- negative voltage current differential resistance
- characteristics
- heterojunction
- quantum well
- resonant tunneling border
- Electronic Science and Technology
- Optoelectronic Information Science and Engineering
- Bauman Moscow State Technical University
- V.N. Karazin Kharkiv National University
-
Hybrid atom-molecule quantum walks in a one-dimensional optical lattice
摘要： We study hybrid atom-molecule quantum walks in one-dimensional optical lattices with two interacting bosonic atoms which may be converted into a molecule. The hybrid atom-molecule energy bands include a continuum band and two isolated bands, which respectively correspond to scattering states and dressed bound states (DBSs). Because of the atom-molecule coupling, the DBSs may appear even in the absence of atom-atom interaction. From an initial state of two atoms occupying the same site, in addition to independent quantum walks which correspond to scattering states, correlated quantum walks appear as a signature of DBSs. Even if the atom-atom interaction and the atom-molecule coupling are much stronger than the tunneling strengths, independent quantum walks may still appear under certain resonant conditions. The correlated quantum walks show two light cones with different propagation velocities, which can be analytically explained by the effective tunneling strengths of the two different DBSs. Furthermore, the effective nearest-neighbor tunneling of DBSs can be suppressed to zero, which can be explained by the destructive interference between the atomic pair and the molecule.
关键词： Quantum walks,dressed bound states,atom-molecule coupling,tunneling,optical lattices
更新于2025-09-23 15:21:01
-
Ultrafast molecular clock with subcycle resolution from correlated electron-nuclear spectra
摘要： To probe ultrafast molecular dynamics, a high spatial-temporal resolution is of crucial importance. Different from the usual pump-probe method, here we present a probing scheme to clock the molecular dynamics with subcycle precision by investigating the correlated electron-nuclear energy spectra in a multicycle laser pulse. The molecular dynamics in the tunneling ionization regime are numerically simulated in a two-dimensional H+2 non-Born-Oppenheimer model. It is found that the asymmetry between the yields of electrons ionized in opposite directions along the laser polarization axis shows peaks and valleys alternately as a function of the nuclear energy. Our results show that the temporally resolved asymmetry of the ionization of electrons can be used as a clock to probe the nuclear Coulomb explosion channel with subcycle resolution and extract the corresponding molecular dynamics accurately. This method can be used even when the intensity averaging of the focused laser beam is considered.
关键词： tunneling ionization regime,subcycle resolution,non-Born-Oppenheimer model,correlated electron-nuclear spectra,ultrafast molecular dynamics
更新于2025-09-23 15:21:01
-
[IEEE 2018 Second International Conference on Computing Methodologies and Communication (ICCMC) - Erode (2018.2.15-2018.2.16)] 2018 Second International Conference on Computing Methodologies and Communication (ICCMC) - Optimization of N+ hetero pocket doped Dual metal Vertical TFET
摘要： In this paper, an N+ hetero pocket doped Dual metal Vertical TFET is proposed. Due to an additional tunneling contribution to current along the body thickness of the device the proposed device offers larger ON current and steeper subthreshold slope (SS) as compare to conventional Tunnel FET. Here, the n+ pocket doping is incorporated near the gate source overlap region. Moreover, the pocket material is optimized with different bandgap materials. The dual metal gate (DMG) is used and compared with single material gate (SMG). Further, with an n+ layer at the p-source side, improvements in the device performance in terms of on-current (10-3A), subthreshold swing, SS (39mV/dec) are achieved. The proposed device is optimized for channel length, silicon body layer thickness, source doping engineering, gate dielectric material. Finally, the analog performance of the device is examined and found the device is suitable for high frequency application.
关键词： Dual Material Gate (DMG),Vertical TFET,Single Material Gate(SMG),Band-to-band tunneling (BTBT)
更新于2025-09-23 15:21:01
-
Visualizing Elementary Reactions of Methanol by Electrons and Holes on TiO2(110) Surface
摘要： Direct visualization and comparison of the elementary reactions induced by electrons and holes are of importance for finding a way to conduct chemical reactions and reaction sequences in a controllable manner. As a semiconductor, TiO2 provides a playground to perform the measurements, and more, the information can be useful for design of high performance TiO2-based catalysts and photocatalysts. Here, we present our investigation on the elementary reactions of CH3OH on TiO2 surface through visualization of specific elementary steps by highly controllable electron- and hole-injection using scanning tunneling microscopy. The distinct sequential routes and their kinetics, namely breaking C-O and O-H bonds by electrons and breaking O-H and C-H bonds by holes, respectively, have been experimentally identified and well elucidated by density functional theory calculations. Our nonlocal h-injection experimental and theoretical results suggest that the delocalized holes in the TiO2 substrate should be responsible for the temperature-dependent h-route reactions. The locally triggered e-route reaction is associated with the fact that the location of the unoccupied hybridization states is much higher than the conduction band onset. Our findings resolve the long standing debate about the intermediate species and reaction mechanism in photocatalytic oxidation of CH3OH. Our proposed protocol offers a powerful means to study elementary reactions induced by electrons and holes on semiconductor surface in general.
关键词： scanning tunneling microscopy,elementary reactions,density functional theory,CH3OH,holes,TiO2,electrons
更新于2025-09-23 15:21:01
-
[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Study on Photoemission and Tunneling in Light - Modulated Scanning Tunneling Microscopy
摘要： We propose the utilization of a light-modulated scanning tunneling microscope (LM-STM) to study the plasmon-enhanced photoemission and tunneling effect between metal tip and Au nanostructures on conductive substrate. The periodic Au nanorods are fabricated by electron beam lithography (EBL) and the topography is imaged using atom force microscopy (AFM) and STM. With irradiation of continuous lasers at 532 and 805 nm, the performance of electron tunneling emission is measured under STM’s ramp mode. We show that, by exciting localized surface plasmon resonances (LSPRs), a tiny laser intensity of around 1 W/cm2 along with a bias voltage less than 50 mV can activate a significantly enhanced tunneling current. This method has the potential for analyzing electron energy states and transport characteristics of surface plasmon.
关键词： plasmonics,Au nanostructures,tunneling,photoemission,STM
更新于2025-09-23 15:21:01
-
High-Quality Reduced Graphene Oxide Electrodes for Sub-Kelvin Studies of Molecular Monolayer Junctions
摘要： Electron transport phenomena in molecular monolayers are complex and potentially different from those for example, molecule?molecule interactions. Unfortunately, access to detailed mechanistic investigations of molecular monolayer junctions at ultralow temperatures is typically hampered by the narrow range of operating temperatures for most large-area device platforms. Here, we present a highly optimized chemically derived graphene material with a near temperature-independent conductance profile. Using this material as a conducting interlayer electrode in solid-state molecular electronic devices, we show robust and reliable large-area molecular junction operation at temperatures ranging from room temperature to below 1 K, and we demonstrate the ability to measure inelastic electron tunneling spectroscopy of a conjugated molecular monolayer at cryogenic temperatures.
关键词： inelastic electron tunneling spectroscopy,cryogenic temperatures,molecular monolayers,graphene,electron transport
更新于2025-09-23 15:21:01
-
Orbital Tuning of Tunnel Coupling in InAs/InP Nanowire Quantum Dots
摘要： We report results on the control of barrier transparency in InAs/InP nanowire quantum dots via the electrostatic control of the device electron states. Recent works demonstrated that barrier transparency in this class of devices displays a general trend just depending on the total orbital energy of the trapped electrons. We show that a qualitatively different regime is observed at relatively low filling numbers, where tunneling rates are rather controlled by the axial configuration of the electron orbital. Transmission rates versus filling are further modified by acting on the radial configuration of the orbitals by means of electrostatic gating, and the barrier transparency for the various orbitals is found to evolve as expected from numerical simulations. The possibility to exploit this mechanism to achieve a controlled continuous tuning of the tunneling rate of an individual Coulomb blockade resonance is discussed.
关键词： quantum dot,InAs/InP,nanowire,Coulomb blockade,tunnel barrier,electron tunneling rate
更新于2025-09-23 15:19:57
-
Carrier transport and recombination dynamics of InAs/GaAs sub-monolayer quantum dot near infrared photodetector
摘要： Here, we present a relative study of tunnel-induced photocarrier escape processes in a laterally coupled InAs sub-monolayer quantum dot-based photodetector (SML QD-PD) as a function of fractional coverage from 0.4 ML to 0.8 ML. Both by simulation and experiment, we have quantitatively described the temperature dependent interband photoresponse spectrally tuned in the near infrared region (835 nm–890 nm) on the basis of mutual competition between the interband carrier recombination and interdot tunneling lifetime with varying SML coverage. The progressively increasing recombination lifetime and decreasing interdot tunneling lifetime with increasing SML coverage has attributed to a faster photoresponse and greater responsivity. At higher coverage fraction, tunnel induced fast speed photocarrier transit through lateral array of SML QDs has been found to be capable of offering a faster temporal response (100 μs) with faithful reproducibility up to higher frequencies (1.3 KHz). Here, we report a powerful strategy to simultaneously tune responsivity, speed of time response and detectivity by externally controlling the SML coverage. This time response is measured to be nine times faster than a conventional SK QD photodetector. With increased coverage, inhibition of dark current due to trapping of injected charge carriers up to higher temperatures have resulted in high sustainable photodetectivity of 8 × 1011 cm Hz1/2 w?1 at ~250 K that offers near room temperature photodetection.
关键词： photoconductive gain,quantum dot photodetector,inter-dot tunneling,submonolayer coverage,near-infrared photoresponse,recombination dynamics,temporal photoresponse
更新于2025-09-23 15:19:57
-
Single-electron current gain in a quantum dot with three leads
摘要： The conductance through a quantum dot (QD) between a source and a drain electrode is usually controlled electrostatically by a nearby gate electrode. A periodic modulation of the conductance versus gate voltage is observed, swapping between Coulomb blockade and single-electron tunneling. By controlling the Fermi level of a third (‘base’) lead attached to the QD, we were able to switch a single-electron current from source to drain, exceeding the single-electron current to or from the base lead. A simple model is presented revealing the role of ground- and excited states within the QD for this dynamic operation of a single-electron transistor.
关键词： electronic wavefunction,coulomb blockade,single-electron tunneling,quantum dot excitations
更新于2025-09-23 15:19:57
-
Research on Degradation of GaN-Based Blue LED Caused by <i>?3</i> Radiation under Low Bias
摘要： GaN multiquantum-well blue light-emitting diodes (LEDs) were radiated with 60Co c-rays for accumulated doses up to 2.5 Mrad (SiO2). The radiation-induced current and 1/f noise degradations were studied when the devices operate at the low bias voltage. The current increased by 2.31 times, and the 1/f noise increased by 275.69 times after a dose of 2.5 Mrad (SiO2). Based on Hurkx’s trap-assisted tunneling model, the degradation of current was explained. c radiation created defects in the space-charge region of LEDs. These defects as generation-recombination centers lead to the increase in the current. In addition, based on the quantum l/f noise theory, the degradation of 1/f noise might be also attributed to these defects, which caused an increase in the Hooge constant and a decrease in the carrier lifetimes. The current and 1/f noise degradations can be attributed to the same physical origin. Compared to the current, the 1/f noise parameter is more sensitive, so it may be used to evaluate the radiation resistance capability of GaN blue LEDs.
关键词： Hooge constant,current degradation,1/f noise degradation,trap-assisted tunneling,γ radiation,GaN,LED
更新于2025-09-23 15:19:57