Observation of an intermediate phase in tungsten doped Sb<sub>2</sub>Te phase change thin films by temperature dependent measurements of structural, optical, and electronic properties

Guo, Shuang; Huang, Ting; Xu, Liping; Shi, Kai; Zhang, J Z; Ji, Xinglong; Hu, Zhigao; Wu, Liangcai; Zhang, Song; Chu, Junhao

doi:10.1088/0022-3727/49/26/265105

Cited by 4 publications

(4 citation statements)

References 40 publications

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“…The assignments and corresponding frequencies of the Raman phonon modes for ST are consistent with previous study29. Although the number and approximate positions of these peaks are the same in the spectra of the corresponding geometries for all four samples, the shift towards lower wave numbers of all the peaks can be extracted with increasing Si concentration.…”

Section: Resultssupporting

confidence: 88%

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Enhanced Crystallization Behaviors of Silicon-Doped Sb2Te Films: Optical Evidences

Guo

Zhang

et al. 2016

Sci Rep

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The optical properties and structural variations of silicon (Si) doped Sb2Te (SST) films as functions of temperature (210–620 K) and Si concentration (0–33%) have been investigated by the means of temperature dependent Raman scattering and spectroscopic ellipsometry experiments. Based upon the changes in Raman phonon modes and dielectric functions, it can be concluded that the temperature ranges for intermediates and transition states are estimated to 150, 120, 90, and 0 K, corresponding to ST, SST25%, SST28%, and SST33% films, respectively. The phenomenon also can be summarized by the thermal evolutions of interband electronic transition energies (En) and partial spectral weight integral (I). The disappearance of intermediate (INT) state for SST33% film between amorphous (AM) and hexagonal (HEX) phases can be attributed to the acceleratory crystallization of HEX phase by Si introduction. It illustrates that the risk of phase separation (Sb and Te) during the cyclic phase-change processes decreases with the increasing Si concentration. The enhanced crystallization behaviors can optimize the data retention ability and the long term stability of ST by Si doping, which are important indicators for phase change materials. The performance improvement has been analyzed qualitatively from the optical perspective.

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Section: Resultssupporting

confidence: 88%

“…It can be summarized that the ST in INT state is composed of crystalline Sb and Te. Besides, in the final HEX geometry, a thimbleful of crystalline Sb and Te still exist due to the slight incomplete recrystallization caused by the slow heating rate2930. Note that no additional peaks can be found in Raman spectra after Si doping.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Crystallization Behaviors of Silicon-Doped Sb2Te Films: Optical Evidences

Guo

Zhang

et al. 2016

Sci Rep

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“…Other researchers have been focusing on the Si 19 , W 20 , Zn 21 , and Cu 22 doping in ST, yet very few device performances have been reported. In addition, the influence of dopants on ST by both experimental and theoretical methods has rarely been studied.…”

Section: Introductionmentioning

confidence: 99%

Atomic scale insight into the effects of Aluminum doped Sb2Te for phase change memory application

Wang

Zheng

et al. 2018

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To date, the unpleasant trade-off between crystallization speed and thermal stability for most phase change materials is detrimental to achieve phase change memory (PCM) with both features of high-speed and good-retention. However, it is proved that Al doping in Sb2Te, served as storage media in PCM, favors both a high writing speed (6 ns) and a good retention (103 °C), as well as a low power consumption. Judging by experimental and theoretical investigations, doped Al atoms prefer to replace Sb in Sb2Te lattice, strongly bonded with 6 Te atoms, to form a homogeneous phase. While in amorphous Al doped Sb2Te (AST), Al atoms are in tetrahedral environment, firmly bonded with four Sb/Te atoms. The strong bonding in Al centered tetrahedron in amorphous AST can obstruct the collective motion of Sb atoms near the matrix boundary, leading to the improvement in thermal stability and the confinement in grain size.

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“…Guo et al (2016) [41] further measured the dielectric function ε of W-doped Sb 2 Te phase change thin films by using temperature regulated VASE type SE. Due to its high absorption, the dielectric function ε was analyzed via surface roughness and isotropic main layer model from the parameters (ψ, ∆ ).…”

Section: Němec Et Al (2011)mentioning

confidence: 99%

Variable angle spectroscopic ellipsometry and its applications in determining optical constants of chalcogenide glasses in infrared

et al. 2018

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The principle of variable angle spectroscopic ellipsometry (VASE) and the data analysis models, as well as the applications of VASE in the characterization of chalcogenide bulk glasses and thin films are reviewed. By going through the literature and summarizing the application scopes of various analysis models, it is found that a combination of various models, rather than any single data analysis model, is ideal to characterize the optical constants of the chalcogenide bulk glasses and thin films over a wider wavelength range. While the reliable optical data in the mid-and far-infrared region are limited, the VASE is flexible and reliable to solve the issues, making it promising to characterize the optical properties of chalcogenide glasses.

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Observation of an intermediate phase in tungsten doped Sb₂Te phase change thin films by temperature dependent measurements of structural, optical, and electronic properties

Cited by 4 publications

References 40 publications

Enhanced Crystallization Behaviors of Silicon-Doped Sb2Te Films: Optical Evidences

Enhanced Crystallization Behaviors of Silicon-Doped Sb2Te Films: Optical Evidences

Atomic scale insight into the effects of Aluminum doped Sb2Te for phase change memory application

Variable angle spectroscopic ellipsometry and its applications in determining optical constants of chalcogenide glasses in infrared

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Observation of an intermediate phase in tungsten doped Sb2Te phase change thin films by temperature dependent measurements of structural, optical, and electronic properties

Cited by 4 publications

References 40 publications

Enhanced Crystallization Behaviors of Silicon-Doped Sb2Te Films: Optical Evidences

Enhanced Crystallization Behaviors of Silicon-Doped Sb2Te Films: Optical Evidences

Atomic scale insight into the effects of Aluminum doped Sb2Te for phase change memory application

Variable angle spectroscopic ellipsometry and its applications in determining optical constants of chalcogenide glasses in infrared

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Observation of an intermediate phase in tungsten doped Sb₂Te phase change thin films by temperature dependent measurements of structural, optical, and electronic properties