A5027132407- Phase-change materials and chalcogenides
- Advanced Memory and Neural Computing
- Chalcogenide Semiconductor Thin Films
- Liquid Crystal Research Advancements
- Transition Metal Oxide Nanomaterials
- Ferroelectric and Negative Capacitance Devices
- Semiconductor materials and devices
- Solid-state spectroscopy and crystallography
- MXene and MAX Phase Materials
- Perovskite Materials and Applications
- Nonlinear Optical Materials Studies
- Chemical and Physical Properties of Materials
- Social Media and Politics
- Polymer Science and Applications
- Advanced Photocatalysis Techniques
- Near-Field Optical Microscopy
- Photonic and Optical Devices
- Polydiacetylene-based materials and applications
- Acoustic Wave Resonator Technologies
- Complex Network Analysis Techniques
- Iterative Methods for Nonlinear Equations
- Polymer composites and self-healing
- Neural Networks and Applications
- Epoxy Resin Curing Processes
- Mining and Gasification Technologies
Toronto Metropolitan University
2024
Intel (United States)
2010-2023
University of Toledo
2009-2016
Carnegie Mellon University
2015
Los Angeles Mission College
2012
Mission College
2007-2010
University of Minnesota
1998
Ferroelectric hafnium and zirconium oxides have undergone rapid scientific development over the last decade, pushing them to forefront of ultralow-power electronic systems. Maximizing potential application in memory devices or supercapacitors these materials requires a combined effort by community address technical limitations, which still hinder their application. Besides favorable intrinsic material properties, HfO2–ZrO2 face challenges regarding endurance, retention, wake-up effect, high...
A novel scalable and stackable nonvolatile memory technology suitable for building fast dense devices is discussed. The cell built by layering a storage element selector. Phase Change Memory (PCM) the selector an Ovonic Threshold Switch (OTS). vertically integrated of one PCM OTS (PCMS) embedded in true cross point array. Arrays are stacked on top CMOS circuits decoding, sensing logic functions. RESET speed 9 nsec endurance 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...
We present the data on temporal (t) drift of parameters in chalcogenide phase change memory that significantly complement earlier published results. The threshold voltage Vth and amorphous state resistance R are shown to as ΔVth∝v ln t R∝tα broad intervals spanning up nine decades time; coefficient v depends glass temperature, but does not depend device thickness. have demonstrated saturates at long enough times can be shorten with temperature increase. All available dynamics fully...
The authors propose a simple physical model of threshold switching in phase change memory cells based on the field induced nucleation conductive cylindrical crystallites. is solved analytically and leads to number predictions including correlations between voltage Vth material parameters, such as barrier radius, amorphous layer thickness, well versus temperature delay time. have carried out verifying experiments, good agreement achieved.
Amorphous chalcogenides have been extensively studied over the last half century due to their application in rewritable optical data storage and non-volatile phase change memory devices. Yet, nature of observed non-ohmic conduction these glasses is still under debate. In this review, we consolidate expand current state knowledge related dc materials. An overview pertinent experimental followed by a review physics localized states that are peculiar chalcogenide glasses. We then describe...
A theory of field-induced crystal nucleation is developed and verified experimentally for the case switching in nanoglasses phase change memory. For symmetry-breaking strong electric fields, it predicts needle-shaped crystallites with barriers lower than that spherical nuclei a field dependent. We have observed bias dependent times temperatures far beyond those typically reported supportive our predictions, particular, time exponential voltage temperature.
Experimental data on switching in phase change memory testify favor of its underlying nucleation mechanism with field dependent barrier. Similar to the standard nucleation, occurs after exponentially long delay time when conditions are not favorable enough, e.g., barrier low or temperature high enough. The statistics is found be consistent as well. A theoretical model outlined.
Hf <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> Zr O xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> based ferroelectric capacitors are deposited via atomic layer deposition with different oxygen content by tuning the ozone dose time during oxidation step. The impact of in is evaluated terms crystalline phase formation and electrical properties. Outstanding device performance good reliability demonstrated for devices highest...
This paper presents key specifications of RRAM-based nonvolatile memory embedded into Intel 22FFL FinFET Technology. is a high performance, ultra low power technology developed for mobile and RF applications providing extensive voltage analog support design flexibility combined with manufacturing costs [1]. Embedded RRAM presented in this achieves 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> cycle endurance 85°C 10-year retention...
A unified field-induced nucleation model provides a common mechanism for switching in chalcogenide phase change memory and related devices of arbitrary thickness. We employ the to derive equations threshold holding voltages terms material parameters device thickness, which are excellent agreement with previous measurements our data.
In this research, we investigate an electroforming and electrically driven insulator-metal transition (E-IMT) characteristic of the NbOx film that follows framework nucleation theory. First, carry out process to form crystalline NbO2 phase, it separated grain-growth according external electric field degree. During process, also study field-induced occurred selectively crystallinity films. We conclude E-IMT was result Peierls between tetragonal rutile phases, experimentally deduce minimum...
Since thermal effects play a major role in filamentary RRAM devices, we compare the two localized thermometry methods developed for such devices. One method is based on short-pulsed measurements and other measurement of minority-carrier injection from filament into semiconductor electrode by thermionic emission. We carried out compared same functional oxide layer. Both indicate that temperature at least ~550 K during device operation. Furthermore, comparison between measured resistance...
The insulating gap and conductive filament growth direction in valence change RRAM devices were studied using the metal-insulator-semiconductor bipolar transistor structure.
We present a phenomenological theory of filamentary resistive random access memory (RRAM) describing the commonly observed features their current-voltage characteristics. Our approach follows thermodynamic developed earlier for chalcogenide and threshold switches largely independent microscopic details. It explains, without adjustable parameters, such as domains filament formation switching, voltage current in SET RESET regimes, relation between set reset voltages, resistance its length,...
In this research, we investigate threshold voltage drift in a B-Te based OTS device under various operation conditions. To aim, of after switching process is examined. From the measurements, find that required to switch back first decreases when interval between pulsespplied for shorter than 10μs, and becomes drift-free afterward. This result implies certain amount heat generated during which results higher local temperature lowers voltage, dissipated completely 10μs. A 3D finite element...
Atomic layer deposition (ALD) of Sb2 Te3 /GeTe superlattice (SL) film on planar and vertical sidewall areas containing TiN metal SiO2 insulator is demonstrated. The peculiar chemical affinity the ALD precursor to substrate surface 2D nature enable growth an in situ crystallized SL with a preferred orientation. shows reduced reset current ≈1/7 randomly oriented Ge2 Te5 alloy. switching induced by transition from (111)-oriented face-centered-cubic (FCC) alloy subsequent melt-quenching-free...
Experimental data on details of SET (crystalline) to RESET (amorphous) transition are presented for Ge <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Sb Te xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> (GST) nonvolatile memory cell. It is shown that the main source heat a GST bulk and interface regions instead contacting electrode. A small-contact-area electrode used primarily supply current into minimize loss from chalcogenide....
We propose a theory of field induced crystal nucleation in disordered glass structure applicable to chalcogenide phase change memory. In the region symmetry breaking strong electric fields, is dominated by cylinder shaped particles with bias dependent barriers. Statistical fluctuations microscopic translate into probabilistic distributions induction times and threshold voltages having respectively log-normal normal shape. These are exponentially sensitive applied voltage, temperature,...
We present a comprehensive theoretical study of $1/f$ noise in chalcogenide glasses aimed at applications to the developing technology phase change memory. Our consideration is based on body formerly established facts about atomic and electronic excitations specific glasses, which have not been considered recent work; we give brief survey relevant information. analysis reveals three possible mechanisms glasses: mobility fluctuations due transitions double-well potentials glass, concentration...
The onset of localized conduction in TaOx- and TiOx-based resistive switching devices during forming has been characterized. novel temperature voltage dependencies times were extracted with pulsed experiments that spanned five orders magnitude time showed three different regimes electroforming. A universal field-induced-nucleation theory which included self-heating effects was used to explain a strong reduction increasing over all observed It shown the effective activation energy for...
Phase change memory (PCM) research has largely focused on bulk properties to evaluate cell efficiency. Now both electrical and thermal interface resistances are characterized shown be critical for understanding power in a novel damascene-GST cell. Interfaces reduce reset 20% current 40% allow scale faster than it would without interfaces.
The results of a comprehensive experimental study relaxation oscillations in chalcogenide phase change memory are presented. Extending the previous work, voltage and current were measured over much longer periods time with broad range applied voltages, load resistances, device thicknesses. effects various reset levels material types also considered. Several oscillation patterns observed; most continuous through measurement period while others exhibited few or no oscillations. Also observed...
We present a model of data retention for phase change memory devices in which the active medium is thin layer chalcogenide glass. Data capability compromised when crystalline path spontaneously formed glassy host, essentially shunting device. determine probability and statistics device failure systems volume fraction below critical percolation theory. In that regime, we show rectilinear formation favored criteria such paths dominate over typical cluster scenario. Our analytical approach,...