Effects of surface alloying and orientation on work function of MoTa metal gate

Xu, Guigui; Wu, Qingyun; Chen, Zhigao; Huang, Zhigao; Feng, Yuan Ping

doi:10.1063/1.3204976

Cited by 29 publications

(17 citation statements)

References 29 publications

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“…This indicates a low anisotropy in the VWF, in contrast with results obtained for the Mo-Ta (bcc) system. 30 When the different atomic terminations are considered, the following trends appear: in general, the Pt termination behaves similarly to the mixed termination, while the Al termination (where possible) shows a lower VWF, which is the lowest VWF possible for a given structure. In other words, this means that Pt atoms at the surface are more dominant than Al atoms in determining the VWF.…”

Section: B Calculation Resultsmentioning

confidence: 99%

“…Another approach to simplify the problem was suggested by Xu et al, 30 which allowed avoiding the possibility of phase Recently, an analytical model of the WF composition dependence of solid solution alloys was proposed 32 and was followed by a detailed experimental study of the Hf-Ni system on HfO 2 . 33 The Hf-Ni alloy features solid state amorphization (SSA), and its EWF was found to depend strongly on the surface enrichment of Hf at its interface with the dielectric, rather than on the average composition of the alloy.…”

Section: Introductionmentioning

confidence: 99%

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Composition and crystallography dependence of the work function: Experiment and calculations of Pt-Al alloys

et al. 2012

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The work function (WF) of several phases of Pt-Al alloys is investigated. A first-principles study is performed to determine the dependence of the vacuum WF (VWF) on the phase, crystallographic orientation, and atomic termination. In parallel, the effective WF (EWF) of these alloys is experimentally measured using metal-oxide semiconductor devices. A detailed microstructural characterization based on x-ray diffraction and transmission electron microscopy allows the comparison between experiment and calculations. It is found that despite the formation of a complex microstructure, the calculated VWF values are in good agreement with the experimental EWF values. The possible VWF range for each phase has a relatively small (∼0.5 eV) span for different orientations and atomic terminations, and it is found that Pt atoms in the terminating plane are more dominant than Al atoms. The results demonstrate that first-principles calculations of the WF of alloys can be used to successfully predict the experimental WF and that knowledge of the microstructure is important for the accuracy of these calculations.

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Section: B Calculation Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Composition and crystallography dependence of the work function: Experiment and calculations of Pt-Al alloys

et al. 2012

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“…The surface calculations were performed on a slab model. 26 Convergence test with respect to the slab thickness was carried out with a 1 Â 1 surface unit cell. It was found that a slab of 12.1 Å is sufficient to get a converged surface energy for the low energy (010) surface termination.…”

Section: Methodsmentioning

confidence: 99%

First-principles investigation of the electronic and Li-ion diffusion properties of LiFePO4 by sulfur surface modification

Zhong

Zhang

et al. 2014

Journal of Applied Physics

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We present a first-principles calculation for the electronic and Li-ion diffusion properties of the LiFePO 4 (010) surface modified by sulfur. The calculated formation energy indicates that the sulfur adsorption on the (010) surface of the LiFePO 4 is energetically favored. Sulfur is found to form Fe-S bond with iron. A much narrower band gap (0.67 eV) of the sulfur surface-modified LiFePO 4 [S-LiFePO 4 (010)] is obtained, indicating the better electronic conductive properties. By the nudged elastic band method, our calculations show that the activation energy of Li ions diffusion along the one-dimensional channel on the surface can be effectively reduced by sulfur surface modification. In addition, the surface diffusion coefficient of S-LiFePO 4 (010) is estimated to be about 10 À11 (cm 2 /s) at room temperature, which implies that sulfur modification will give rise to a higher Li ion carrier mobility and enhanced electrochemical performance. V C 2014 AIP Publishing LLC.

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“…However, both binary systems exhibit very small mutual solubility and therefore the results cannot be verified by experiment. 12 Xu et al 13,14 used a similar technique with the generalized gradient approximation and projector augmented wave pseudopotential for Ni-Pt and Mo-Ta binary systems. Since the solute atoms in all calculations were concentrated only in the surface atomic monolayer, a comparison with experiments might be difficult for these systems.…”

Section: Introductionmentioning

confidence: 99%

Work function calculation of solid solution alloys using the image force model

Rothschild

Eizenberg

2010

Phys. Rev. B

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The electronic work function of polycrystalline solid solution alloys is being analytically calculated using three different approaches. All approaches are derived by assuming that the alloys are in equilibrium and therefore surface segregation causes a difference between the surface composition and the bulk composition. An approach based on the image force, an approach based on the dipole layer formed due to electronegativity differences, and a simple surface concentration approach are compared to published experimental results. The image force model has a good agreement with the experiments, while the dipole-layer approach has a poor agreement, challenging the conventional concept of the double layer.

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Effects of surface alloying and orientation on work function of MoTa metal gate

Cited by 29 publications

References 29 publications

Composition and crystallography dependence of the work function: Experiment and calculations of Pt-Al alloys

Composition and crystallography dependence of the work function: Experiment and calculations of Pt-Al alloys

First-principles investigation of the electronic and Li-ion diffusion properties of LiFePO4 by sulfur surface modification

Work function calculation of solid solution alloys using the image force model

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