Structure of the Ge–Sb–Te phase-change materials studied by theory and experiment

Sun, Zhimei; Kyrsta, Stepan; Mušić, Denis; Ahuja, Rajeev; Schneider, Jochen M.

doi:10.1016/j.ssc.2007.05.018

Cited by 62 publications

(53 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Characterization of amorphous thin films is challenging, but in general amorphous compounds can have enhanced physical and chemical properties. For instance, metallic glasses have superior mechanical properties compared to corresponding crystals [15,16], amorphous pharmaceuticals are remarkably more soluble than their crystalline counterparts [17] and Ge-Sb-Te alloys are used for optical and electrical data storage based on amorphous-to-crystalline transitions [18,19].…”

Section: Introductionmentioning

confidence: 99%

Bonding and elastic properties of amorphous AlYB

Mušić

Hensling

Pazur

et al. 2013

Solid State Communications

Self Cite

View full text Add to dashboard Cite

a b s t r a c tWe have studied the bonding and elastic properties of amorphous AlYB 14 using theoretical and experimental means. Based on pair distribution functions and Voronoi tessellation, the icosahedral bonding is expected. A rather large Young's modulus of 365 GPa is predicted for amorphous AlYB 14 .To verify these predictions, we have measured density, pair distribution functions, binding energy and elastic properties of Al-Y-B thin films synthesized by magnetron sputtering. The calculated and measured densities are with a deviation of 3.5% in good agreement. The measured binding energy and pair distribution functions are also consistent with icosahedral bonding. The measured Young's modulus is 305 719 GPa, which is 16% smaller than the theoretical value and hence in good agreement. Overall consistency between theory and experiments was obtained indicating that the computational strategy employed here is useful to describe correlations between bonding, elasticity, density as well as (chemical) short range order and may hence enable future knowledge-based design of these ternary borides which show great potential for surface protection applications.

show abstract

Section: Introductionmentioning

confidence: 99%

Bonding and elastic properties of amorphous AlYB

Mušić

Hensling

Pazur

et al. 2013

Solid State Communications

Self Cite

View full text Add to dashboard Cite

show abstract

“…32 In this work, we will restrict ourselves to the m-GST phase due to the key role that it plays in optical storage applications. 3,5,[10][11][12][13][14] Experimental techniques such as high-resolution transmission electron microscopy ͑HRTEM͒, x-ray diffraction study ͑XRD͒, extended x-ray absorption fine-structure spectroscopy ͑EXAFS͒, and theoretical studies for the m-GST [27][28][29][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] phase have reported that the Te atoms occupy the anion sites and Ge, Sb, and the intrinsic vacancies ͑20% in GST͒ occupy the cation sites in the RS structure. Despite the seeming simplicity, the structural details of the m-GST structure are still under intense debate.…”

Section: Introductionmentioning

confidence: 99%

Atomistic origins of the phase transition mechanism in Ge2Sb2Te5

Silva

Walsh

Wei

et al. 2009

Journal of Applied Physics

View full text Add to dashboard Cite

Tricritical behavior of the RI-RV rotator phase transition in a mixture of alkanes with nanoparticles J. Chem. Phys. 135, 134505 (2011) Pressure-induced amorphization in mayenite (12CaO·7Al2O3) J. Chem. Phys. 135, 094506 (2011) Influence of Al2O3 crystallization on band offsets at interfaces with Si and TiNx Appl. Phys. Lett. 99, 072103 (2011) Temperature induced transition from hexagonal to circular pits in graphite oxidation by O2 Appl. Phys. Lett. 99, 044102 (2011) Phase transformation of Ho2O3 at high pressure J. Appl. Phys. 110, 013526 (2011) Additional information on J. Appl. Phys. The fast and reversible phase transition mechanism between crystalline and amorphous phases of Ge 2 Sb 2 Te 5 has been in debate for several years. Through employing first-principles density functional theory calculations, we identify a direct structural link between the metastable crystalline and amorphous phases. The phase transition is driven by the displacement of Ge atoms along the rocksalt ͓111͔ direction from stable octahedron to high energy unstable tetrahedron sites close to the intrinsic vacancy regions, which generates a high energy intermediate phase between metastable and amorphous phases. Due to the instability of Ge at the tetrahedron sites, the Ge atoms naturally shift away from those sites, giving rise to the formation of local-ordered fourfold motifs and the long-range structural disorder. Intrinsic vacancies, which originate from Sb 2 Te 3 , lower the energy barrier for Ge displacements, and hence, their distribution plays an important role in the phase transition. The high energy intermediate configuration can be obtained experimentally by applying an intense laser beam, which overcomes the thermodynamic barrier from the octahedron to tetrahedron sites. The high figure of merit of Ge 2 Sb 2 Te 5 is achieved from the optimal combination of intrinsic vacancies provided by Sb 2 Te 3 and the instability of the tetrahedron sites provided by GeTe.

show abstract

“…Thus, there is atomic alternation and a principal octahedral coordination. Via density functional theory calculations, energetically optimal sublattice occupations, towards which the systems tend by annealing, have been determined [11,13,14]. Yet, the theoretically most favorable structure is likely not obtained in experiments given the mismatch between optical properties calculated for those structures and measured ones [15].…”

Section: The Crystalline Phasementioning

confidence: 99%