Papers by writam banerjee
Extended Abstracts of the 2011 International Conference on Solid State Devices and Materials, 2011
Extended Abstracts of the 2012 International Conference on Solid State Devices and Materials, 2012
2010 10th IEEE International Conference on Solid-State and Integrated Circuit Technology, 2010
Extended Abstracts of the 2010 International Conference on Solid State Devices and Materials, 2010
Extended Abstracts of the 2012 International Conference on Solid State Devices and Materials, 2012
Nanoscale Research Letters, 2013
Improved switching characteristics were obtained from high-κ oxides AlOx, GdOx, HfOx, and TaOx in... more Improved switching characteristics were obtained from high-κ oxides AlOx, GdOx, HfOx, and TaOx in IrOx/high-κx/W structures because of a layer that formed at the IrOx/high-κx interface under external positive bias. The surface roughness and morphology of the bottom electrode in these devices were observed by atomic force microscopy. Device size was investigated using high-resolution transmission electron microscopy. More than 100 repeatable consecutive switching cycles were observed for positive-formatted memory devices compared with that of the negative-formatted devices (only five unstable cycles) because it contained an electrically formed interfacial layer that controlled ‘SET/RESET’ current overshoot. This phenomenon was independent of the switching material in the device. The electrically formed oxygen-rich interfacial layer at the IrOx/high-κx interface improved switching in both via-hole and cross-point structures. The switching mechanism was attributed to filamentary conduc...
MATERIALS TRANSACTIONS, 2011
The aim of this work is to investigate the particle size and morphology of the nanocrystals in th... more The aim of this work is to investigate the particle size and morphology of the nanocrystals in the non-volatile memory device by annular dark field (ADF) scanning transmission electron microscopy (STEM) and conventional transmission electron microscopy (CTEM) techniques. With respect to TEM investigation, statistical analysis on STEM image can acquire the size and density of nanocrystals more accurately than on TEM image. In addition, ADF STEM images successfully provide powerful evidences revealing the structure of IrO x nanocrystals as a core shell structure, where the inner structure is rich in Ir and the outer area is abundant in O or Al. This method could be one of the efficient way for examining the nanocrystals with a complicated cored structure.
Journal of Physics D: Applied Physics, 2013
Japanese Journal of Applied Physics, 2012
The Kepler mission has to date found almost 6000 planetary transit-like signals, utilizing three ... more The Kepler mission has to date found almost 6000 planetary transit-like signals, utilizing three years of data for over 170,000 stars at extremely high photometric precision. Due to its design, contamination from eclipsing binaries, variable stars, and other transiting planets results in a significant number of these signals being false positives (FPs). This directly affects the determination of the occurrence rate of Earth-like planets in our Galaxy, as well as other planet population statistics. In order to detect as many of these FPs as possible, we perform ephemeris matching among all transiting planet, eclipsing binary, and variable star sources. We find that 685 Kepler Objects of Interest (KOIs)-12% of all those analyzed-are FPs as a result of contamination, due to 409 unique parent sources. Of these, 118 have not previously been identified by other methods. We estimate that ∼35% of KOIs are FPs due to contamination, when performing a first-order correction for observational bias. Comparing single-planet candidate KOIs to multi-planet candidate KOIs, we find an observed FP fraction due to contamination of 16% and 2.4% respectively, bolstering the existing evidence that multi-planet KOIs are significantly less likely to be FPs. We also analyze the parameter distributions of the ephemeris matches and derive a simple model for the most common type of contamination in the Kepler field. We find that the ephemeris matching technique is able to identify low signal-to-noise FPs that are difficult to identify with other vetting techniques. We expect FP KOIs to become more frequent when analyzing more quarters of Kepler data, and note that many of them will not be able to be identified based on Kepler data alone.
Applied Physics Letters, 2007
The physical and electrical characteristics of atomic layer deposited TiN nanocrystals embedded i... more The physical and electrical characteristics of atomic layer deposited TiN nanocrystals embedded in high-k Al2O3 films in a metal/Al2O3∕[TiN∕Al2O3]∕SiO2∕p-Si structure have been investigated. High-resolution transmission electron microscopy and x-ray photoelectron spectroscopy show the formation of tiny TiN nanocrystals embedded in Al2O3 films after subsequent annealing treatment. The TiN nanocrystals with a high density of >1×1012∕cm2 and a small size of <3nm have been observed. A large hysteresis memory window of ∼4.3V at small sweeping gate voltage of 3V has been observed as compared with a pure Al2O3 charge trapping layer, due to highly charge confinement in the TiN metal nanocrystals. The hysteresis memory window of 1.4V has also been observed under an extremely small sweeping gate voltage of 1V. A large memory window of ∼3.9V is observed after 10years of retention. A maximum hysteresis memory window is limited by both of the nanocrystal density and leakage current at a hi...
Applied Physics Letters, 2022
To inaugurate energy-efficient hardware as a solution to complex tasks, information processing pa... more To inaugurate energy-efficient hardware as a solution to complex tasks, information processing paradigms shift from von Neumann to non-von Neumann computing architectures. Emerging electronic devices compete with speed, energy, and performance to revolutionize the neural hardware system where training and inference must achieve milestones. In this Perspective, we discuss the essential criteria for training and inference in various nonvolatile neuromorphic systems such as filamentary resistive switching, interfacial resistive switching, electrochemical random-access memory, and ferroelectric memory. We present a holistic analysis of technical requirements to design ideal neuromorphic hardware in which linearity is the critical aspect during training, whereas retention is the essential criterion of inference. Finally, we evaluate the prospect of a futuristic neuromorphic hardware system by optimizing the training and inference dilemma.
Small, 2021
The first report on ion transport through atomic sieves of atomically thin 2D material is provide... more The first report on ion transport through atomic sieves of atomically thin 2D material is provided to solve critical limitations of electrochemical random‐access memory (ECRAM) devices. Conventional ECRAMs have random and localized ion migration paths; as a result, the analog switching efficiency is inadequate to perform in‐memory logic operations. Herein ion transport path scaled down to the one‐atom‐thick (≈0.33 nm) hexagonal boron nitride (hBN), and the ionic transport area is confined to a small pore (≈0.3 nm2) at the single‐hexagonal ring. One‐atom‐thick hBN has ion‐permeable pores at the center of each hexagonal ring due to weakened electron cloud and highly polarized B–N bond. The experimental evidence indicates that the activation energy barrier for H+ ion transport through single‐layer hBN is ≈0.51 eV. Benefiting from the controlled ionic sieving through single‐layer hBN, the ECRAMs exhibit superior nonvolatile analog switching with good memory retention and high endurance....
Scientific Reports, 2019
All solid-state lithium-ion transistors are considered as promising synaptic devices for building... more All solid-state lithium-ion transistors are considered as promising synaptic devices for building artificial neural networks for neuromorphic computing. However, the slow ionic conduction in existing electrolytes hinders the performance of lithium-ion-based synaptic transistors. In this study, we systematically explore the influence of ionic conductivity of electrolytes on the synaptic performance of ionic transistors. Isovalent chalcogenide substitution such as Se in Li3PO4 significantly reduces the activation energy for Li ion migration from 0.35 to 0.253 eV, leading to a fast ionic conduction. This high ionic conductivity allows linear conductance switching in the LiCoO2 channel with several discrete nonvolatile states and good retention for both potentiation and depression steps. Consequently, optimized devices demonstrate the smallest nonlinearity ratio of 0.12 and high on/off ratio of 19. However, Li3PO4 electrolyte (with lower ionic conductivity) shows asymmetric and nonlinea...
ACS Omega, 2017
Variability control over the resistive switching process is one of the key requirements to improv... more Variability control over the resistive switching process is one of the key requirements to improve the performance stability of the resistive random access memory (RRAM) devices. In this study, we show the improvement of the variability of the resistive switching operation in the TiO x /Al 2 O 3 bilayer RRAM devices. The achievement is based on the thickness engineering of the Al 2 O 3 layer. A thick Al 2 O 3 dielectric actively takes part to control the resistive switching behavior; on the contrary, the ultrathin layer of Al 2 O 3 behaves as the tunnel barrier in the structure. At lower voltage, the low resistance state conductions follow the trap-assisted tunneling and Fowler− Nordheim tunneling for the thick and thin Al 2 O 3 RRAMs, respectively. Finally, the variation control in device forming, SET voltage distribution, high resistance state, low resistance state, and resistance ratio is achieved with the TiO x /Al 2 O 3 bilayer RRAM devices by interfacial band engineering with an ultrathin Al 2 O 3 dielectric material.
Resistive random access memory (RRAM) is a promising emerging nonvolatile memory which offer high... more Resistive random access memory (RRAM) is a promising emerging nonvolatile memory which offer high density integration in the form of cross-bar array design. Selector devices are a vital requirement to suppress the cross-talk issue. In this letter, we are going to demonstrate the coexistence of resistive switching (RS) and threshold switching (TS) in an ultrathin 2-nm Aluminium oxide (AlO x )-based crossbar RRAM devices. Depending on current level the device itself can switch from TS to RS mode with a nonlinearity of >10 2 . Stable TS of >10 3 cycles has been achieved at 10 nA. Achievements of this letter offers the usability of 2-nm AlO x RRAM devices as a selector and as a memory device for high density crossbar array integration.
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Papers by writam banerjee