Electrical conduction in chalcogenide glasses of phase change memory

Abstract

Electrical conduction in chalcogenide glasses of phase change memory App. Phys. Rev. 2012, 8 (2012 Understanding the multistate SET process in Ge-Sb-Te-based phase-change memory J. Appl. Phys. 112, 064901 (2012) Highly sensitive tactile sensors integrated with organic transistors Appl. Phys. Lett. 101, 103308 (2012) Highly sensitive tactile sensors integrated with organic transistors APL: Org. Electron. Photonics 5, 206 (2012) On the nature of the interfacial layer in ultra-thin TiN/LaLuO3 gate stacks Amorphous chalcogenides have been extensively studied over the last half century due to their application in rewritable optical data storage and in non-volatile phase change memory devices. Yet, the nature of the observed non-ohmic conduction in these glasses is still under debate. In this review, we consolidate and expand the current state of knowledge related to dc conduction in these materials. An overview of the pertinent experimental data is followed by a review of the physics of localized states that are peculiar to chalcogenide glasses. We then describe and evaluate twelve relevant transport mechanisms with conductivities that depend exponentially on the electric field. The discussed mechanisms include various forms of Poole-Frenkel ionization, Schottky emission, hopping conduction, field-induced delocalization of tail states, space-charge-limited current, field emission, percolation band conduction, and transport through crystalline inclusions. Most of the candidates provide more or less satisfactory fits of the observed non-linear IV data. Our analysis calls upon additional studies that would enable one to discriminate between the various alternative models. V C 2012 American Institute of Physics. [http://dx.

High-field electrical transport in amorphous phase-change materials

“…The former treatment assumes that a charge carrier excited above the mobility edge is immediately re-trapped at a site of distance Dz or s, usually called the inter-trap distance. As mentioned by Nardone et al, 18 the validity of combining band-transport with a constant traveling distance is questionable. A charge carrier excited to the mobility edge would participate in band-transport with the band mobility that is much larger than the hopping mobility.…”

“…A recent broad review evaluated the relevance of a few of these mechanisms with respect to the melt-quenched materials used in PCRAM. 18 Therein, space-charge limited currents, hopping, and Schottky emission were excluded as possible transport mechanisms because electrical transport is independent of the length of the conducting channel (SCLC) and because half the optical gap E G corresponds well to the activation energy for conduction E a at room temperature (hopping and Schottky-emission). In line with the latter reasoning, the conductivity of our devices/materials is independent of the device length (cf.…”

Электрофизические свойства и механизмы переноса в тонких пленках материалов фазовой памяти на основе халькогенидных полупроводников квазибинарного разреза GeTe-Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-

“…Наличие различ-ных зависимостей тока от напряжения связано с до-минированием разных механизмов переноса носителей заряда [6][7][8].…”

“…Это может быть обусловлено ионизацией мелких локализованных состояний [6], а также эффектом Пула-Френкеля, приводящим к уменьшению потенциально-го барьера при увеличении приложенного напряжения. Однако экспериментальные зависимости могут быть описаны как экспоненциальной, так и степенной зави-симостью, с высокими коэффициентами детерминации.…”

Low-loss latching microwave switch using thermally pulsed non-volatile chalcogenide phase change materials

“…Phase change materials which transform back and forth between crystalline or amorphous states 1 have been in use by the optical storage industry for two decades for rewritable compact discs and digital video discs, 2,3 utilizing the change in reflectivity to store information as dark or shiny spots. Recently, non-volatile resistance state memories have also been introduced using phase change materials, [4][5][6][7] exploiting the concomitant change in electrical resistivity to achieve information storage. In either case, an applied heat pulse (by laser pulse for optical storage or by electric pulse for resistance memory) is used to switch states.…”