Structural fingerprints of electronic change in the phase-change-material: Ge2Sb2Te5

Abstract

In this paper, we generate aGe 2 Sb 2 Te 5 models via ab initio molecular dynamic simulations, track the dynamic changes of network at 500 K, and correlate the structural changes in the course of the simulation with changes in electronic structure. Considerable fluctuations of the electronic gap are observed even for a model in equilibrium. We compare our study to experiments and other simulations.

Inverse simulated annealing: Improvements and application to amorphous InSb

“…While at high density, the bonding of the In atoms is mostly octahedrallike, at low density a sizable fraction of tetrahedral-like geometries had been observed. This variability originates from a close competition between tetrahedral-like and octahedral-like sites, as previously found in related amorphous tellurides [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] . Nevertheless, this immediately suggests that in the presence of nanovoids in the amorphous/liquid phase, the inclusion of van der Waals interactions might be particularly important and may result is a somewhat higher density 46 .…”

Properties of amorphous GaN from first-principles simulations

“…The band gaps obtained from our models are much smaller than the experimental value 3.1eV 7 . This is not a surprising result, since DFT always underestimates the gap 26 . If we estimate the mobility gap (the gap between extended valence and conduction states), we obtain E g ≈ 3.0eV .…”

Building block modeling technique: Application to ternary chalcogenide glasses g-Ge2As4SeCai1, Zhang2, Drabold3 2011Phys. Rev. BSelf Cite

“…The difference here may imply that the constraint counting of Ge-As-Se alloys in this cross-linked 3-D region should be carefully reconsidered. Violations of the 8-N rule are well known in other chalcogenide systems 18 .…”

“…We should point out here that under-coordinated (3-fold) Ge atoms and over-coordinated (3-fold) Se atoms do not introduce localized states or mid-gap states, especially in g-AsGe 0.8 Se 0.8 where most Se are 3-fold, which implies that they are not defects in the network. It is well known that the LDA method always under-estimates the magnitude of the band gap, so other techniques could be applied to get a better predication for the band gap 18 . To sum up, we introduced a BB modeling technique and applied it to obtain atomic models of gGe 2 As 4 Se 4 and g-AsGe 0.8 Se 0.8 .…”