Ab initio energy loss spectra of Si and Ge nanowires

Palummo, Maurizia; Hogan, Conor; Ossicini, Stefano

doi:10.1039/c5cp05074j

Cited by 3 publications

(7 citation statements)

References 54 publications

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“…As expected from previously published results (see for instance Ref. 28,29,40,41 ), both these curves obey to the power law dependence…”

supporting

confidence: 89%

Crystal Phase Effects in Si Nanowire Polytypes and Their Homojunctions

Amato¹,

Kaewmaraya²,

Zobelli³

et al. 2016

Nano Lett.

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Recent experimental investigations have confirmed the possibility to synthesize and exploit polytypism in group IV nanowires. Driven by this promising evidence, we use first-principles methods based on density functional theory and many-body perturbation theory to investigate the electronic and optical properties of hexagonal-diamond and cubic-diamond Si NWs as well as their homojunctions. We show that hexagonal-diamond NWs are characterized by a more pronounced quantum confinement effect than cubic-diamond NWs. Furthermore, they absorb more light in the visible region with respect to cubic-diamond ones and, for most of the studied diameters, they are direct band gap materials. The study of the homojunctions reveals that the diameter has a crucial effect on the band alignment at the interface. In particular, at small diameters the band-offset is type-I whereas at experimentally relevant sizes the offset turns up to be of type-II. These findings highlight intriguing possibilities to modulate electron and hole separations as well as electronic and optical properties by simply modifying the crystal phase and the size of the junction.

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“…As expected from previously published results (see for instance Ref. 28,29,40,41 ), both these curves obey to the power law dependence…”

supporting

confidence: 89%

Crystal Phase Effects in Si Nanowire Polytypes and Their Homojunctions

Amato¹,

Kaewmaraya²,

Zobelli³

et al. 2016

Nano Lett.

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“…A large bandgap variation in Si would result into a large variation of VP energy. This rationale is explained by the extended Drude model for semiconductors, [36] and also reflected in atomistic simulations from Palummo et al [35] Boundary effects are also known to contribute to the increase of the VP energy within a single nanostructure, [20,37] and could be partially responsible for the observed increase of Si VP energy as the beam approaches the pillar boundary as shown in Figure 6g. This boundary effect was also observed by Hobbs et al [20] Here, given than the energy shift is ten times larger, 1.2 eV, and the length scale smaller, we believe that quantum confinement is being added to the boundary effect, leading to higher VP energy modulation.…”

Section: Eels Analysis: Si Volume Plasmon Engineeringmentioning

confidence: 80%

“…The data follows well a functional dependence of the form 1/ with close to unity. [35] The best fit is found for = 0.7 (red solid red curve). A model with = 1, which includes passivating the Si surface with hydrogen atoms, does not fit the data as well.…”

Section: Methodsmentioning

confidence: 95%

“…EELS mapping is an important analytical technique that allows one to study the spatial dependence of specific inelastic features in the EEL spectrum. [20,31] (blue solid curve), which takes into account saturating the Si surface dangling bonds with hydrogen atoms, [33][34][35] does not fit the experimental data as well. Figure 6h shows that the Si VP energy is lithographically tuned by 1.2 eV from the bulk VP energy value, which results in a significant amount of VP energy control.…”

Section: Eels Analysis: Si Volume Plasmon Engineeringmentioning

confidence: 99%

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Patterning Si at the 1 nm Length Scale with Aberration‐Corrected Electron‐Beam Lithography: Tuning of Plasmonic Properties by Design

Manfrinato

Camino

Stein

et al. 2019

Adv Funct Materials

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Patterning of materials at single nanometer resolution allows engineering of quantum confinement effects, as these effects are significant at these length scales, and yields direct control over electro‐optical properties. Silicon is by far the most important material in electronics, and the ability to fabricate Si‐based devices of the smallest dimensions for novel device engineering is highly desirable. The work presented here uses aberration‐corrected electron‐beam lithography combined with dry reactive ion etching to achieve both: patterning of 1 nm features and surface and volume plasmon engineering in Si. The nanofabrication technique employed here produces nanowires with a line edge roughness (LER) of 1 nm (3σ). In addition, this work demonstrates tuning of the Si volume plasmon energy by 1.2 eV from the bulk value, which is one order of magnitude higher than previous attempts of volume plasmon engineering using lithographic methods.

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“…Because of their natural compatibility with silicon based technologies, cubicdiamond (3C) Si-NWs have being extensively theoretically studied and several experiments have already characterized their main structural and electronic properties. 5,6,[50][51][52]54,122 It has been possible to fabricate, for example, single-crystal Si-NWs with diameters as small as 1 nm and lengths of a few tens of micrometers. Ultrathin NWs show a substantial blue-shi when decreasing the size as revealed by scanning tunneling spectroscopy measurements.…”

Section: Cubic-diamond Si Nanowiresmentioning

confidence: 99%