Inherent electron and hole trapping in amorphous phase-change memory materials: Ge₂Sb₂Te₅

Abstract

When the amorphous state of a chalcogenide phase-change material is formed inside an electronic-memory device via Joule heating, caused by an applied voltage pulse, it is in the presence of...

Multi-enzyme mimics – cracking the code of subcellular cascade reactions and their potential biological applications

“…This is presumably due to the high interfacial energy and the formation of internal electron-hole traps within the bimetallic NPs, which, in turn, indicates the higher chemical stability of AgPt NPs over the monometallic Ag NPs, which restricts the release of ions into the solution during the reaction. 73 Dong's group reported that NiPd showed multienzyme activity and is employed for the colorimetric detection of glucose. NiPd hNPs had a hollow nanostructure, which provided an enhanced surface area with exposed active sites for the catalytic reaction of the nanozyme for the active adsorption and trapping of substrate molecules including TMB and H 2 O 2 in the hollow NPs that lead to a high catalytic efficiency of NiPd hNPs as well.…”

Atomistic Modeling of Charge‐Trapping Defects in Amorphous Ge‐Sb‐Te Phase‐Change Memory Materials

“…[16][17][18][19][20][21] The intrinsic charge-trapping processes at the localized electronic states of the amorphous material have also been considered as an alternative (electronic) explanation of the resistance drift. [22][23][24] Atomistic simulations have reported the existence of several localized unoccupied and occupied electronic states in the vicinity of the bandgap in amorphous phase-change materials. Zipoli et al associated the localization of defects in the bandgap of models of glassy GeTe with clusters of Ge atoms, in which at least one Ge atom is over-or undercoordinated.…”

“…[27] Recently, we also showed that spontaneous electron-and holetrapping events are energetically favorable at the conduction-and valence-band edges in amorphous Ge 2 Sb 2 Te 5 . [24] One-electron traps produce deep occupied states in the bandgap, located in close proximity to the top of the valence band, while one-hole traps lead to the creation of unoccupied states around midgap. [24] The intrinsic defective-octahedral Ge and Sb sites inside the amorphous Ge 2 Sb 2 Te 5 network have been found to be responsible for the charge trapping.…”

“…[24] The near-linear triatomic Te-Ge/Sb-Te/Ge/Sb environments from the axial bonds in "seesaw" 4-coordinated or 5-coordinated defective-octahedral configurations correspond to the atomic geometries where the extra electrons and holes are trapped. [24] In addition, five-membered chain-like structural motifs, comprised of two connected triads, have also been identified as potential charge-trapping sites. [24] Understanding charge-trapping processes at the localized defect electronic states of the glassy state is of great importance with respect to the operational conditions in PCRAM devices.…”

“…[24] In addition, five-membered chain-like structural motifs, comprised of two connected triads, have also been identified as potential charge-trapping sites. [24] Understanding charge-trapping processes at the localized defect electronic states of the glassy state is of great importance with respect to the operational conditions in PCRAM devices. In this study, we aim to extend our previous work by performing electron-and hole-trapping calculations for amorphous models of the two binary end-members of the Ge-Sb-Te compositional tie-line, namely, GeTe and Sb 2 Te 3 , the eutectic composition GeTe 4 , and for a 900-atom model of the canonical ternary Ge 2 Sb 2 Te 5 composition.…”