Enhanced temperature stability and exceptionally high electrical contrast of selenium substituted Ge2Sb2Te5 phase change materials

Koch, Christine; Hansen, Anna‐Lena; Dankwort, Torben; Schienke, Gerrit; Paulsen, Melf; Meyer, Dominik; Wimmer, Martin; Wuttig, Matthias; Kienle, Lorenz; Bensch, Wolfgang

doi:10.1039/c7ra01140g

Cited by 27 publications

(15 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In situ STEM heating experiments were performed with a Gatan 652 double-tilt heating holder. Previous studies showed a stable temperature measurement [56,57]. A heating rate of 10 °C/min was applied, and the temperature was maintained for 10 min before the images were taken for each temperature plateau to minimize thermal drift and ensure a robust estimation of the sample temperature.…”

Section: Temperature-dependent Stem Analysismentioning

confidence: 99%

Multidimensional thermally-induced transformation of nest-structured complex Au-Fe nanoalloys towards equilibrium

et al. 2021

Self Cite

View full text Add to dashboard Cite

Bimetallic nanoparticles are often superior candidates for a wide range of technological and biomedical applications owing to their enhanced catalytic, optical, and magnetic properties, which are often better than their monometallic counterparts. Most of their properties strongly depend on their chemical composition, crystallographic structure, and phase distribution. However, little is known of how their crystal structure, on the nanoscale, transforms over time at elevated temperatures, even though this knowledge is highly relevant in case nanoparticles are used in, e.g., high-temperature catalysis. Au-Fe is a promising bimetallic system where the low-cost and magnetic Fe is combined with catalytically active and plasmonic Au. Here, we report on the in situ temporal evolution of the crystalline ordering in Au-Fe nanoparticles, obtained from a modern laser ablation in liquids synthesis. Our in-depth analysis, complemented by dedicated atomistic simulations, includes a detailed structural characterization by X-ray diffraction and transmission electron microscopy as well as atom probe tomography to reveal elemental distributions down to a single atom resolution. We show that the Au-Fe nanoparticles initially exhibit highly complex internal nested nanostructures with a wide range of compositions, phase distributions, and size-depended microstrains. The elevated temperature induces a diffusion-controlled recrystallization and phase merging, resulting in the formation of a single face-centered-cubic ultrastructure in contact with a body-centered cubic phase, which demonstrates the metastability of these structures. Uncovering these unique nanostructures with nested features could be highly attractive from a fundamental viewpoint as they could give further insights into the nanoparticle formation mechanism under non-equilibrium conditions. Furthermore, the in situ evaluation of the crystal structure changes upon heating is potentially relevant for high-temperature process utilization of bimetallic nanoparticles, e.g., during catalysis.

show abstract

Section: Temperature-dependent Stem Analysismentioning

confidence: 99%

Multidimensional thermally-induced transformation of nest-structured complex Au-Fe nanoalloys towards equilibrium

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…6(a) doping of GST thin lms with Sn as well as substitution of Te with Se have an enhancing effect on the optical contrast. 94,95 Overall, by tuning the degree of structural order regarding the vacancy distribution and the associated degree of electron localization as well as texture of GST phase change alloys, distinct differences in optical and electrical properties within GST alloys can be achieved. Consequently, a proper engineering of disorder in different GST phases might enable the realization of multilevel resistance/reectivity states accomplished by crystalline-to-crystalline phase changes, resulting in a drastic increase of the data storage density and reduction in the energy consumption of working devices, respectively.…”

Section: Optical Reectivitymentioning

confidence: 99%

Phase change thin films for non-volatile memory applications

2019

View full text Add to dashboard Cite

show abstract

“…GST has been of interest for optical storage applications 9 , but it has not been ideal for phase-change random access memory (PCRAM) applications due to its low crystallization temperature (Tc), poor data retention ability 10 and low resistance contrast. Se is a smaller and more covalent atom compared to Te and it is found that Se doping enhances the phase change properties of GST 11 – 15 . There are reports that Se alloys such as Ga-Sb–Se, Sb–Se possess higher Tc, better data retention, higher switching speed, lower thermal conductivity 16 , and lower melting temperature with respect to GST.…”

Section: Introductionmentioning

confidence: 99%

Structural transformation and phase change properties of Se substituted GeTe

Shekhawat

Haritha

Madhavan

et al. 2021

Sci Rep

View full text Add to dashboard Cite

GeTe1−xSex (0 ≤ x ≤ 1.0) alloys have been prepared both in bulk and thin film forms to study the effect of selenium (Se) substitution for tellurium (Te) on the phase change properties. It is observed that with increasing Se substitution in GeTe, the structure transforms from rhombohdral structure to orthorhombic structure. Rietveld Refinement analysis support the phase transformation and show that the short and long bond lengths in crystalline GeTe decrease with increasing Se substitution but the rate of reduction of shorter bond length is more than the longer bond length. The GeTe1−xSex thin films undergo amorphous to crystalline phase change when annealed at high temperatures. The transition temperature shows an increasing trend with the Se substitution. The contrast in electrical resistivity between the amorphous and crystalline states is 104 for GeTe, and with the Se substitution, the contrast increases considerably to 106 for GeTe0.5Se0.5. Devices fabricated with thin films show that the threshold current decreases with the Se substitution indicating a reduction in the power required for WRITE operation. The present study shows that the crystalline structure, resistance, bandgap, transition temperature and threshold voltage of GeTe can be effectively controlled and tuned by the substitution of Te by Se, which is conducive for phase change memory applications.

show abstract

Enhanced temperature stability and exceptionally high electrical contrast of selenium substituted Ge₂Sb₂Te₅ phase change materials

Cited by 27 publications

References 60 publications

Multidimensional thermally-induced transformation of nest-structured complex Au-Fe nanoalloys towards equilibrium

Multidimensional thermally-induced transformation of nest-structured complex Au-Fe nanoalloys towards equilibrium

Phase change thin films for non-volatile memory applications

Structural transformation and phase change properties of Se substituted GeTe

Contact Info

Product

Resources

About