Stoichiometry dependence of resistance drift phenomena in amorphous GeSnTe phase-change alloys

Luckas, Jennifer; Piarristeguy, Andréa; Bruns, Gunnar; Jost, Peter; Grothe, S.; Schmidt, Rüdiger; Longeaud, Christophe; Wuttig, Matthias

doi:10.1063/1.4769871

Cited by 31 publications

(26 citation statements)

References 18 publications

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“…The absolute values of the drift exponent v determined in this work match quite well to literature data on memory cells in case of GST [16,17,31,34,[41][42][43][44] as well as on thin film samples for AIST and GeTe [17,44] as depicted in Table 1. The difference of the drift behavior between amorphous as-deposited samples compared to the melt-quenched cells seems to be sufficiently treated with the introduction of the virtual age t s .…”

Section: Resistance Drift In Amorphous As-deposited Phase Change Filmssupporting

confidence: 76%

Role of activation energy in resistance drift of amorphous phase change materials

et al. 2014

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The time evolution of the resistance of amorphous thin films of the phase change materials Ge 2 Sb 2 Te 5 , GeTe and AgIn-Sb 2 Te is measured during annealing at T = 80 • C. The annealing process is interrupted by several fast temperature dips to determine the changing temperature dependence of the resistance. This procedure enables us to identify to what extent the resistance increase over time can be traced back to an increase in activation energy E A or to a rise of the prefactor R * . We observe that, depending on the material, the dominating contribution to the increase in resistance during annealing can be either a change in activation energy (Ge 2 Sb 2 Te 5 ) or a change in prefactor (AgIn-Sb 2 Te). In the case of GeTe, both contribute about equally. We conclude that any phenomenological model for the resistance drift in amorphous phase change materials that is based on the increase of one parameter alone (e.g., the activation energy) cannot claim general validity.

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Section: Resistance Drift In Amorphous As-deposited Phase Change Filmssupporting

confidence: 76%

Role of activation energy in resistance drift of amorphous phase change materials

et al. 2014

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“…10 However, the drift of the amorphous state a) resistivity in amorphous GeTe (a-GeTe) is rather high. 11 Ge 15 Te 85 , on the contrary shows much slower crystallization kinetics on a timescale of 100 ls, 10 but a more stable amorphous state.…”

Section: Introductionmentioning

confidence: 91%

Defects in amorphous phase-change materials

et al. 2013

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Understanding the physical origin of threshold switching and resistance drift phenomena is necessary for making a breakthrough in the performance of low-cost nanoscale technologies related to nonvolatile phase-change memories. Even though both phenomena of threshold switching and resistance drift are often attributed to localized states in the band gap, the distribution of defect states in amorphous phase-change materials (PCMs) has not received so far, the level of attention that it merits. This work presents an experimental study of defects in amorphous PCMs using modulated photocurrent experiments and photothermal deflection spectroscopy. This study of electrically switching alloys involving germanium (Ge), antimony (Sb) and tellurium (Te) such as amorphous germanium telluride (a-GeTe), a-Ge 15 Te 85 and a-Ge 2 Sb 2 Te 5 demonstrates that those compositions showing a high electrical threshold field also show a high defect density. This result supports a mechanism of recombination and field-induced generation driving threshold switching in amorphous chalcogenides. Furthermore, this work provides strong experimental evidence for complex trap kinetics during resistance drift. This work reports annihilation of deep states and an increase in shallow defect density accompanied by band gap widening in aged a-GeTe thin films.

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“…It has been widely used to study disordered semiconductors such as hydrogenated amorphous silicon (a‐Si:H) but not only. The MPC has also been applied to a large variety of materials such as (i) lead sulfide (PbS) quantum dot arrays (), (ii) antimony sulfide (Sb

) (), (iii) copper gallium selenium compounds (CGSe) (), (iv) phase change alloys like germanium telluride (GeTe) () or germanium tin telluride (GeSnTe) (), (v) cadmium telluride (CdTe) (), and (vi) organic semiconductors like pentacene films .…”

Section: Introductionmentioning

confidence: 99%

New insight into the modulated photocurrent technique using 2D full numerical simulations

Lachaume

Longeaud

Kleider

2016

Physica Status Solidi (a)

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The modulated photocurrent technique has been used for a few decades now to provide information on the localized density of states (DOS) in semiconductor thin films. In previous studies, a simplified analytical treatment has been performed in 1D to derive equations that one has been using to reconstruct the DOS located near the majority carrier band. In these former studies, all the physical quantities were considered as constant within the sample depth, however, we know that it is not the case especially in the presence of a strong gradient of photogeneration in some materials. In this paper, for the first time, we show results of 2D simulations of the modulated photocurrent (MPC) experiment in order to study the effect of vertical photogeneration inhomogeneity on the MPC and to discuss the validity of the 1D assumption in more realistic cases. Thanks to these 2D simulations, new insight is gained in the understanding of the MPC experiment. Indeed, we show that we can explain and reproduce some of the experimental behaviors that the 1D theory failed to predict. Hydrogenated amorphous silicon (a-Si:H) is taken as a reference material for demonstration purposes, but this 2D approach can also be extended to other semiconductor materials and other types of inhomogeneities.

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Stoichiometry dependence of resistance drift phenomena in amorphous GeSnTe phase-change alloys

Cited by 31 publications

References 18 publications

Role of activation energy in resistance drift of amorphous phase change materials

Role of activation energy in resistance drift of amorphous phase change materials

Defects in amorphous phase-change materials

New insight into the modulated photocurrent technique using 2D full numerical simulations

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