Thin film alloy mixtures for high speed phase change optical storage: A study on (Ge1Sb2Te4)1−x(Sn1Bi2Te4)x

Lee, Tae-Yon; Kim, Ki-Bum; Cheong, Byung‐ki; Lee, Taek Sung; Park, Sung Jin; Lee, Kyeong Seok; Kim, Won Mok; Kim, Soon Gwang

doi:10.1063/1.1476705

Cited by 37 publications

(13 citation statements)

References 9 publications

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“…The chemical modification approach proposed by Young et al (1986) could possibly be adopted to meet the requirements. The elements Bi, Sn and In are considered as dopants to tailor the crystallization speed of GST (Lee et al 1999;Wang et al 2004a, b;Akiyama et al 2001; Kojima and Yamada 2001;Lee et al 2002;Wang et al 2005). The stoichiometric compounds modified by dopants might pave a new avenue to tailor phase change materials towards suitable performance.…”

Section: Introductionmentioning

confidence: 99%

Influence of doping upon the phase change characteristics of Ge2Sb2Te5

et al. 2006

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The influence of doping upon the phase change characteristics of Ge 2 Sb 2 Te 5 (GST) has been determined with a variety of techniques including four-point-probe electrical resistance measurements, grazing incidence Xray diffraction (XRD), X-ray reflectometry (XRR) and a variable incident angle spectroscopic ellipsometer (VASE) and a static tester. Doping with Bi, Sn or In maintains the NaCl-type crystalline structure of GST but expands the lattice due to the larger atomic radii. Sufficient optical contrast is exhibited and can be presumably correlated with the pronounced density change upon crystallization. In the Bi and Sn doped case transition temperatures are reduced with regard to the undoped case. Ultra-fast crystallization within 10 ns is demonstrated, which is correlated with a single NaClstructure phase and a lower transition temperature arising from the weaker bonds. In the In doped case, however, crystallization is retarded, which can be correlated with the observed phase separation and the increased transition temperature.

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Section: Introductionmentioning

confidence: 99%

Influence of doping upon the phase change characteristics of Ge2Sb2Te5

et al. 2006

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“…[11][12][13][14] Among them doped alloys derived from "eutectic" Sb x Te, showing a growth-dominant crystallization behavior, appear the most obvious choice for both high data transfer rate and high-density recording. [15][16][17][18][19][20] These materials are currently used in optical disk formats including DVD+ RW, DVD-RW, Blu-ray disk, 21 and HD-DVD, 22 and are also proposed for the line concept PRAM.…”

Section: Influence Of Capping Layers On the Crystallization Of Doped mentioning

confidence: 99%

Influence of capping layers on the crystallization of doped SbxTe fast-growth phase-change films

Pandian

Kooi

Hosson

et al. 2006

Journal of Applied Physics

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Isothermal crystallization of doped Sb x Te fast-growth phase-change films, with and without capping layers, was investigated using transmission electron microscopy, which provided direct and quantitative information on nucleation and growth processes separately. Two types of amorphous dielectric layers, ZnS -SiO 2 and GeCrN, were used for sandwiching the Sb x Te films to form typical trilayer stacks, which are the active part in applications. The nucleation and growth parameters of Sb x Te films were found to be influenced by the dielectric capping layers. The crystal growth rate is temperature dependent and it reduces when the film is sandwiched between the dielectric layers. The reduction in growth rate differs with the capping layer type. The capping layer influence on the growth rate is pronounced at lower temperatures ϳ160°C, but tends to vanish at higher temperatures ϳ200°C. The activation energy for crystal growth is 2.4± 0.3 eV for an uncapped film and it increases ϳ40% when the capping layers, GeCrN or ZnS -SiO 2 , are added. A temperature and time dependent nucleation rate is found and it is accelerated ϳ1.7 times by GeCrN layers, whereas it is retarded ϳ5 times by ZnS -SiO 2 layers. The activation energy for crystal nucleation is 6.1± 0.4 eV for an uncapped film and it is not noticeably altered by the capping layers. These variations observed in the crystallization kinetics are attributed to variations in interface energy between the phase-change film and the capping layers or vacuum and the confinement effect by the capping layers on the phase-change film.

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“…As for the films annealed at 200 C, analyses of TEM diffraction patterns led to a single fcc crystalline state for Ge Sb Te film [inset (c)], but a mixed state of fcc and hcp phases for Ge Sb Te Sn Bi Te film [inset (d)]. According to our previous study [7], such an accelerated crystallization in the alloy added with Sn Bi Te is due to the reduced strengths of various interatomic bonds in this alloy.…”

Section: A Phase-change Materials Propertiesmentioning

confidence: 94%

“…In this letter, we suggest a new phase-change-memory cell technology utilizing reversible changes between fcc and hcp crystalline phases of Ge Sb Te Sn Bi Te chalcogenide alloy [7]. …”

Section: Introductionmentioning

confidence: 99%

A nonvolatile memory based on reversible phase changes between fcc and hcp

Ahn

Kang

Cheong

et al. 2005

IEEE Electron Device Lett.

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A nonvolatile memory technology utilizing reversible changes between fcc and hcp crystalline phases is proposed. In this new type of phase-change memory, data are stored in different forms of crystalline phases of (Ge 1 Sb 2 Te 4 ) 0 8 (Sn 1 Bi 2 Te 4 ) 0 2 chalcogenide alloy. RESET operation produces the less conductive metastable fcc phase via melt-quenching from the more conductive stable hcp phase and SET operation involves a phase change from fcc directly to hcp. Both RESET and SET operations can be completed as fast as 70 ns with large changes in cell resistance.

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Thin film alloy mixtures for high speed phase change optical storage: A study on (Ge1Sb2Te4)1−x(Sn1Bi2Te4)x

Cited by 37 publications

References 9 publications

Influence of doping upon the phase change characteristics of Ge2Sb2Te5

Influence of doping upon the phase change characteristics of Ge2Sb2Te5

Influence of capping layers on the crystallization of doped SbxTe fast-growth phase-change films

A nonvolatile memory based on reversible phase changes between fcc and hcp

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