Atomistic study of the structural and electronic properties of a-Si:H/c-Si interfaces

Santos, Iván; Cazzaniga, Marco; Onida, Giovanni; Colombo, Luciano

doi:10.1088/0953-8984/26/9/095001

Cited by 7 publications

(9 citation statements)

References 34 publications

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“…We also find H atoms in a bridging position (0.2 atoms per simulation cell). Santos et al 25 also investigated this defect but it was not reported by Tosolini et al 6 The number of other defects is less than 0.1 per simulation cell. The differences with Santos et al and Tosolini et al are possibly due to the different method used to prepare the structure: they used tight-binding MD whereas we used DFT MD.…”

Section: Preparation Of the Structurementioning

confidence: 91%

Band Offsets at the Interface between Crystalline and Amorphous Silicon from First Principles

Jarolimek¹,

Hazrati²,

Groot

et al. 2017

Phys. Rev. Applied

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The band offsets between crystalline and hydrogenated amorphous silicon (a-Si:H) are key parameters governing the charge transport in modern silicon hetrojunction solar cells. They are an important input for macroscopic simulators that are used to further optimize the solar cell. Past experimental studies, using X-ray photoelectron spectroscopy (XPS) and capacitance-voltage measurements, have yielded conflicting results on the band offset. Here we present a computational study on the band offsets. It is based on atomistic models and density-functional theory (DFT). The amorphous part of the interface is obtained by relatively long DFT first-principles moleculardynamics (MD) runs at an elevated temperature on 30 statistically independent samples. In order to obtain a realistic conduction band position the electronic structure of the interface is calculated with a hybrid functional. We find a slight asymmetry in the band offsets, where the offset in the valence band (0.30 eV) is larger than in the conduction band (0.17 eV). Our results are in agreement with the latest XPS measurements that report a valence band offset of 0.3 eV [M. Liebhaber et al., Appl. Phys. Lett. 106, 031601 (2015)].

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Section: Preparation Of the Structurementioning

confidence: 91%

Band Offsets at the Interface between Crystalline and Amorphous Silicon from First Principles

Jarolimek¹,

Hazrati²,

Groot

et al. 2017

Phys. Rev. Applied

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“…These electrons not only are far away from the nucleus but also sometimes exhibit spin polarization. In the conventional DFT (including LDA and GGA) calculations, the electron-electron repulsion of the Kohn-Sham equations is still based on a singleparticle approximation 57,58 . The electronic exchange function sees spin-pair electrons as single particles, in which case, the number of K-S orbitals is half of the total number.…”

Section: Mott Phase Transitionmentioning

confidence: 99%

Recent progress in the phase-transition mechanism and modulation of vanadium dioxide materials

et al. 2018

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Metal-to-insulator transition (MIT) behaviors accompanied by a rapid reversible phase transition in vanadium dioxide (VO 2) have gained substantial attention for investigations into various potential applications and obtaining good materials to study strongly correlated electronic behaviors in transition metal oxides (TMOs). Although its phasetransition mechanism is still controversial, during the past few decades, people have made great efforts in understanding the MIT mechanism, which could also benefit the investigation of MIT modulation. This review summarizes the recent progress in the phase-transition mechanism and modulation of VO 2 materials. A representative understanding on the phase-transition mechanism, such as the lattice distortion and electron correlations, are discussed. Based on the research of the phase-transition mechanism, modulation methods, such as element doping, electric field (current and gating), and tensile/compression strain, as well as employing lasers, are summarized for comparison. Finally, discussions on future trends and perspectives are also provided. This review gives a comprehensive understanding of the mechanism of MIT behaviors and the phase-transition modulations.

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“…We also considered structural models for amorphous silicon overlayers, using the same computational setup. In this case, the initial structures were obtained by slicing the atomic positions at a cubic-Si/amorphous-Si interface, as determined by tight-binding molecular dynamics simulations [15], placing it on a 4 × 4 Ag(111) supercell, and performing further geometrical relaxation. This resulted in the structural model shown in Fig.…”

mentioning

confidence: 99%

Optical response and ultrafast carrier dynamics of the silicene-silver interface

Cinquanta¹,

Fratesi

Conte

et al. 2015

Phys. Rev. B

Self Cite

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We report a combined experimental and theoretical study of the optical response of epitaxial silicene on silver. The silicene/Ag(111) ultraviolet-visible absorption spectra, which turn out to be strongly nonadditive, are analyzed in the framework of ab initio calculations. Electronic transitions involving silver states are found to provide huge contributions to the optical absorption of silicene, compatible with a strong Si-Ag hybridization. The results are independent of the specific silicene configuration and are also worked out for thin amorphous silicon. This points to a dimensionality-driven peculiar dielectric response of the two-dimensional-silicon/silver interface, which is confirmed by means of transient-reflectance spectroscopy. The latter shows a metalliclike relaxation time, hence demonstrating the effects of the strong hybridization arising in silicene/Ag (111) Recently, the integration of silicene in field-effect transistors (FET) [1] opened new challenges in the comprehension of the chemical and physical properties of this elusive two-dimensional (2D) allotropic form of silicon. Intense efforts have been devoted to the study of the epitaxial silicene/Ag(111) system in order to elucidate the presence of massless Dirac fermion in analogy with graphene [2,3]. Although recent experiments report on the linear dispersive bands [4], strong hybridization effects have been invoked as responsible for the disruption of π and π * bands in silicene superstructures on silver [5][6][7][8][9]. In this framework, the measured ambipolar effect in silicene-based FET characterized by a relatively high mobility when Ag is withdrawn, points to a complex physics at the silicene-silver interface, demanding a deeper comprehension of its details on the atomic scale.The present paper aims at elucidating the role of the Ag(111) metallic support in determining the physical properties of the Si/Ag (2D) interface, by means of optical techniques combined with theoretical calculations. In particular we show that interface states built up by mixed silicon and silver wave functions have a striking impact on the optical response of the low-dimensional Si/Ag system.

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Atomistic study of the structural and electronic properties of a-Si:H/c-Si interfaces

Cited by 7 publications

References 34 publications

Band Offsets at the Interface between Crystalline and Amorphous Silicon from First Principles

Band Offsets at the Interface between Crystalline and Amorphous Silicon from First Principles

Recent progress in the phase-transition mechanism and modulation of vanadium dioxide materials

Optical response and ultrafast carrier dynamics of the silicene-silver interface

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