Viscosity and elastic constants of thin films of amorphous Te alloys used for optical data storage

Kalb, Johannes; Spaepen, Frans; Pedersen, T. P. Leervad; Wuttig, Matthias

doi:10.1063/1.1610775

Cited by 85 publications

(80 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Homopolar bonds and Ge T atoms are thus kinetically stabilized by the fast-quenching rates but are energetically unfavourable. These findings suggest that the relaxation of the amorphous state and, by corollary, the drift process could be linked with the removal of homopolar bonds, in agreement with experiments showing 35,36 that the drift of PCMs is accompanied by stress relief. We show below that drift involves more than this, but we first have to understand why the removal of tetrahedrally coordinated Ge atoms reduces the energy and stress.…”

Section: Resultssupporting

confidence: 75%

Aging mechanisms in amorphous phase-change materials

et al. 2015

View full text Add to dashboard Cite

Aging is a ubiquitous phenomenon in glasses. In the case of phase-change materials, it leads to a drift in the electrical resistance, which hinders the development of ultrahigh density storage devices. Here we elucidate the aging process in amorphous GeTe, a prototypical phase-change material, by advanced numerical simulations, photothermal deflection spectroscopy and impedance spectroscopy experiments. We show that aging is accompanied by a progressive change of the local chemical order towards the crystalline one. Yet, the glass evolves towards a covalent amorphous network with increasing Peierls distortion, whose structural and electronic properties drift away from those of the resonantly bonded crystal. This behaviour sets phase-change materials apart from conventional glass-forming systems, which display the same local structure and bonding in both phases.

show abstract

Section: Resultssupporting

confidence: 75%

Aging mechanisms in amorphous phase-change materials

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Because of structural relaxation, the viscosity increases with time, which according to equation (1) will cause a reduction in the growth velocity over time that has to be accounted for. The increase of viscosity with time is well captured by 25 ZðT; tÞ…”

Section: Resultsmentioning

confidence: 99%

Crystal growth within a phase change memory cell

2014

View full text Add to dashboard Cite

In spite of the prominent role played by phase change materials in information technology, a detailed understanding of the central property of such materials, namely the phase change mechanism, is still lacking mostly because of difficulties associated with experimental measurements. Here, we measure the crystal growth velocity of a phase change material at both the nanometre length and the nanosecond timescale using phase-change memory cells. The material is studied in the technologically relevant melt-quenched phase and directly in the environment in which the phase change material is going to be used in the application. We present a consistent description of the temperature dependence of the crystal growth velocity in the glass and the super-cooled liquid up to the melting temperature.

show abstract

“…The mechanical stress relaxation model in the PCRAM structure is based on the internal hydrostatic pressure built at reset stage due to a considerable density difference between the crystalline and amorphous phases (5∼7%). 13,14 After the amorphization, the residual compressed stress in the amorphous active region will tend to release over time, and the volume dilation will tend to increase as well, causing time-dependent increase in the resistance. 10 …”

Section: Introductionmentioning

confidence: 99%

Role of an encapsulating layer for reducing resistance drift in phase change random access memory

Jin

Kim

et al. 2014

AIP Advances

View full text Add to dashboard Cite

Phase change random access memory (PCRAM) devices exhibit a steady increase in resistance in the amorphous phase upon aging and this resistance drift phenomenon directly affects the device reliability. A stress relaxation model is used here to study the effect of a device encapsulating layer material in addressing the resistance drift phenomenon in PCRAM. The resistance drift can be increased or decreased depending on the biaxial moduli of the phase change material (YPCM) and the encapsulating layer material (YELM) according to the stress relationship between them in the drift regime. The proposed model suggests that the resistance drift can be effectively reduced by selecting a proper material as an encapsulating layer. Moreover, our model explains that reducing the size of the phase change material (PCM) while fully reset and reducing the amorphous/crystalline ratio in PCM help to improve the resistance drift, and thus opens an avenue for highly reliable multilevel PCRAM applications.

show abstract

Viscosity and elastic constants of thin films of amorphous Te alloys used for optical data storage

Cited by 85 publications

References 26 publications

Aging mechanisms in amorphous phase-change materials

Aging mechanisms in amorphous phase-change materials

Crystal growth within a phase change memory cell

Role of an encapsulating layer for reducing resistance drift in phase change random access memory

Contact Info

Product

Resources

About