scholarly journals An lnterband Tunnel Oscillator: Intrinsic Bistability and Hysteresis of Trapped Hole Charge in a Double-Barrier Structure

VLSI Design ◽  
1998 ◽  
Vol 8 (1-4) ◽  
pp. 237-245 ◽  
Author(s):  
F. A. Buot
Keyword(s):  
Resonant Tunneling ◽  
Large Scale ◽  
Step Function ◽  
Rate Equations ◽  
Device Structure ◽  
Electron Hole ◽  
Hole Charge ◽  
Interband Tunneling ◽  
High Bandwidth ◽  
Tunneling Dynamics

We introduced a novel high-frequency source based on interband tunneling. A polarization-induced oscillation of trapped-hole-charge occurs in an AlGaSb/InAs/ AlGaSb resonant tunneling device. Rate equations for Zener tunneling, polarization, and electron-hole recombination is used to analyze the nonlinear dynamics of this device structure. The nonoscillatory state is unstable against the limit-cycle operation. The amplitude of trapped hole oscillation increases with bias, but the time-averaged values can be approximated by a step function. These lead to the hysteresis of the averaged trapped hole charge in AlGaSb barrier, and to the experimental intrinsic bistability in AlGaSb/InAs/AlGaSb resonant tunneling device. Large-scale time-dependent simulation of quantum transport with interband-tunneling dynamics is needed for the design optimization of this novel class of oscillator useful for high-bandwidth applications.

scholarly journals NanoLEDs for energy-efficient and gigahertz-speed spike-based sub-λ neuromorphic nanophotonic computing

Nanophotonics ◽  
2020 ◽  
Vol 9 (13) ◽  
pp. 4149-4162 ◽  
Author(s):  
Bruno Romeira ◽  
José M. L. Figueiredo ◽  
Julien Javaloyes
Keyword(s):  
Neural Networks ◽  
Energy Efficient ◽  
High Speed ◽  
Dynamic Properties ◽  
Optical Computing ◽  
Differential Conductance ◽  
Rate Equations ◽  
Dynamical Equations ◽  
Electrical Modulation ◽  
High Bandwidth

AbstractEvent-activated biological-inspired subwavelength (sub-λ) photonic neural networks are of key importance for future energy-efficient and high-bandwidth artificial intelligence systems. However, a miniaturized light-emitting nanosource for spike-based operation of interest for neuromorphic optical computing is still lacking. In this work, we propose and theoretically analyze a novel nanoscale nanophotonic neuron circuit. It is formed by a quantum resonant tunneling (QRT) nanostructure monolithic integrated into a sub-λ metal-cavity nanolight-emitting diode (nanoLED). The resulting optical nanosource displays a negative differential conductance which controls the all-or-nothing optical spiking response of the nanoLED. Here we demonstrate efficient activation of the spiking response via high-speed nonlinear electrical modulation of the nanoLED. A model that combines the dynamical equations of the circuit which considers the nonlinear voltage-controlled current characteristic, and rate equations that takes into account the Purcell enhancement of the spontaneous emission, is used to provide a theoretical framework to investigate the optical spiking dynamic properties of the neuromorphic nanoLED. We show inhibitory- and excitatory-like optical spikes at multi-gigahertz speeds can be achieved upon receiving exceptionally low (sub-10 mV) synaptic-like electrical activation signals, lower than biological voltages of 100 mV, and with remarkably low energy consumption, in the range of 10–100 fJ per emitted spike. Importantly, the energy per spike is roughly constant and almost independent of the incoming modulating frequency signal, which is markedly different from conventional current modulation schemes. This method of spike generation in neuromorphic nanoLED devices paves the way for sub-λ incoherent neural elements for fast and efficient asynchronous neural computation in photonic spiking neural networks.

Effects of charge accumulation and biasing on resonant tunneling energies and tunneling dynamics

1994 ◽  
Author(s):  
David A. Cardimona ◽  
Paul M. Alsing ◽  
Anjali Singh ◽  
Vassilios Kovanis
Keyword(s):  
Resonant Tunneling ◽  
Charge Accumulation ◽  
Tunneling Dynamics

Reconfigurable nonvolatile boolean logic with one-transistor-two-memristor for in-memory computing

2021 ◽  
Author(s):  
Ziling Wang ◽  
Li Luo ◽  
Jie Li ◽  
Lidan Wang ◽  
shukai duan
Keyword(s):  
Large Scale ◽  
Full Adder ◽  
Boolean Logic ◽  
Device Structure ◽  
Von Neumann ◽  
Computing Paradigm ◽  
Operation Process ◽  
Strong Candidate ◽  
High Flexibility ◽  
Logic Functions

Abstract In-memory computing is highly expected to break the von Neumann bottleneck and memory wall. Memristor with inherent nonvolatile property is considered to be a strong candidate to execute this new computing paradigm. In this work, we have presented a reconfigurable nonvolatile logic method based on one-transistor-two-memristor (1T2M) device structure, inhibiting the sneak path in the large-scale crossbar array. By merely adjusting the applied voltage signals, all 16 binary Boolean logic functions can be achieved in a single cell. More complex computing tasks including one-bit parallel full adder and Set-Reset latch have also been realized with optimization, showing simple operation process, high flexibility, and low computational complexity. The circuit verification based on cadence PSpice simulation is also provided, proving the feasibility of the proposed design. The work in this paper is intended to make progress in constructing architectures for in-memory computing paradigm.

scholarly journals Applying Biomimetic Principles to Thermoelectric Cooling Devices for Water Collection

2017 ◽  
Vol 7 (3) ◽  
pp. 27
Author(s):  
Kyle B Davidson ◽  
Bahram Asiabanpour ◽  
Zaid Almusaied
Keyword(s):  
Large Scale ◽  
Cost Effective ◽  
Thermoelectric Cooling ◽  
Device Structure ◽  
Cooling Systems ◽  
Cooling Devices ◽  
Water Collection ◽  
Maximum Water ◽  
The Ideal

The shortage of freshwater resources in the world has developed the need for sustainable, cost-effective technologies that can produce freshwater on a large scale. Current solutions often have extensive manufacturing requirements, or involve the use of large quantities of energy or toxic chemicals. Atmospheric water generating solutions that minimize the depletion of natural resources can be achieved by incorporating biomimetics, a classification of design inspired by nature. This research seeks to optimize thermoelectric cooling systems for use in water harvesting applications by analyzing the different factors that affect surface temperature and water condensation in TEC devices. Further experiments will be directed towards developing a robust, repeatable system, as well as an accurate measurement system. Surface modifications, device structure and orientation, and power generation will also be studied to better understand the ideal conditions for maximum water collection in thermoelectric cooling systems.

Hydrogen Etching Effects During Plasma Doping Processes and Impact on Shallow Junction Formation

1995 ◽  
Vol 396 ◽  
Author(s):  
Shu Qin ◽  
James D. Bernstein ◽  
Chung Chan
Keyword(s):  
Integrated Circuits ◽  
Large Scale ◽  
Impurity Profile ◽  
Device Structure ◽  
Hydrogen Etching ◽  
Shallow Junction ◽  
Dopant Profile ◽  
Plasma Doping ◽  
Junction Formation ◽  
Hydrogen Radicals

AbstractHydrogen etching effects in plasma ion implantation (PII) doping processes alter device structure and implant dopant profile and reduce the retained implant dose. This has particular relevance to the shallow junction devices of ultra large scale integrated circuits (ULSI). Hydrogen etching of semiconductor materials including Si, poly-Si, SiO2, Al, and photoresist films have been investigated. The effects of varying different PII process parameters are presented. The experimental data show that the spontaneous etching by hydrogen radicals enhanced by ion bombardment is responsible for the etching phenomena. A computer simulation is used to predict the as-implanted impurity profile and the retained implant dose for a shallow junction doping when the etching effect is considered.

scholarly journals Construction of NiMoS3/BC heterostructure photoanodes and optimization of light scattering to improve the photovoltaic performance of dye sensitized solar cells (DSSCs)

2021 ◽  
Author(s):  
T Sumathi ◽  
Sonia A Fredricka ◽  
G Deepa
Keyword(s):  
Solar Cells ◽  
Large Scale ◽  
Photovoltaic Performance ◽  
Dye Sensitized Solar Cells ◽  
Photocurrent Density ◽  
Electron Hole ◽  
Dye Sensitized ◽  
Electron Hole Pair ◽  
Conversion Efficiencies ◽  
Sensitized Solar Cells

Abstract In the last two decades, dye sensitized solar cells (DSSCs) have gotten a lot of attention from researchers and have progressed quickly. To promote commercialization and large-scale application of DSSCs, their efficiency should be increased. This paper details significant advancements in advanced NiMoS3/BC nanocomposites for improving photoanodes and DSSC conversion efficiencies. The fabricated electrode samples were characterized by XRD, SEM, TEM, Raman, UV, PL and BET to explore the structural, morphological and optical properties. A significant reduction band gap with enhanced light absorption and rapid prevention of electron hole pair was explored by UV-DRS and PL studies. The photocurrent density-voltage (J-V) and IPCE characteristics were analyzed for assembled solar cell. The NiMoS3/BC (NMSC5) nanocomposite DSSC showed a PCE of 8.85%, far higher than that of the NiMoS3 (2.45%) and a PCE value equivalent to Pt CE (4.79 %). The enhanced PCE of the proposed electrodes are also discussed in scientifically.

THE PAULI PRINCIPLE AND QUANTUM TRANSPORT

1994 ◽  
Vol 08 (21n22) ◽  
pp. 1377-1385 ◽  
Author(s):  
S.A. GURVITZ ◽  
H.J. LIPKIN ◽  
Ya. S. PRAGER
Keyword(s):  
Quantum Wells ◽  
Resonant Tunneling ◽  
Fock Space ◽  
Pauli Principle ◽  
Semiconductor Heterostructures ◽  
Rate Equations ◽  
Semiconductor Quantum Wells ◽  
Occupation Numbers ◽  
The One ◽  
Space Wave

A new method using Fock space wave functions is proposed for studying resonant tunneling in semiconductor quantum wells. The use of binary occupation numbers as dynamical variables, rather than properties of individual electrons, manifestly takes account of electron statistics, which enables investigation of the influence of the Pauli principle on resonant tunneling in the presence of inelastic scattering. Applied to the evaluation of the resonant current in semiconductor heterostructures, our approach predicts considerable deviations from the one-electron and rate equations pictures.

Latent disciplinal clashes concerning the batch dissolution of minerals, and their wider implications

2018 ◽  
Vol 15 (2) ◽  
pp. 113 ◽  
Author(s):  
Victor W. Truesdale ◽  
Jim Greenwood
Keyword(s):  
Large Scale ◽  
Dissolution Kinetics ◽  
Mineral Dissolution ◽  
Atomic Scale ◽  
Rate Equations ◽  
Silicate Mineral ◽  
Waste Products ◽  
Calcite Dissolution ◽  
Macro Scale ◽  
Made In

Environmental contextMineral dissolution kinetics are important to understand natural processes including those increasingly used to store waste carbon dioxide and highly radio-active nuclides, and those involved in the amelioration of climate change and sea-level rise. We highlight a mistake made in the fundamental science that has retarded progress in the field for over 40 years. Its removal suggests improved ways to approach dissolution studies. AbstractMineral dissolution kinetics are fundamental to biogeochemistry, and to the application of science to reduce the deleterious effects of humanity’s waste products, e.g. CO2 and radio-nuclides. However, a mistake made in the selection of the rate equation appropriate for use at the macro-scale of the aquatic environment has stymied growth in major aspects of the subject for some 40 years. This paper identifies the mistake, shows how it represents a latent disciplinal clash between two rate equations, and explores the misunderstandings that resulted from it. The paper also briefly explores other disciplinal clashes. Using the example of calcite dissolution, the paper also shows how the phenomenon of ‘non-ideal’ dissolution, which is prevalent in alumino-silicate mineral dissolution, as well as with calcite, has obscured the clash. The paper provides new information on plausible mechanisms, the absence of which has contributed to the problem. Finally, it argues that disciplinal clashes need to be minimised so that a rigorous description of dissolution at the large scale can be matched to findings at the atomic, or near-atomic, scale.

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