Metastable Group IV Allotropes and Solid Solutions: Nanoparticles and Nanowires

Barth, Sven; Seifner, Michael S.; Maldonado, Stephen

doi:10.1021/acs.chemmater.9b04471

Cited by 27 publications

(29 citation statements)

References 594 publications

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“…However, recent works argued that so far pure hexagonal-diamond C crystals might not have been obtained [12,13] and that the observed materials most likely correspond to high stacking disorder in cubic diamonds (3C in the Ramsdell notation) [12][13][14]. Instead, in the case of Si and Ge, it has been recently undeniably proved that 2H-nanowires (NWs) can be grown following different approaches [15] such as crystal transfer methods [2,[16][17][18], strain and photo-induced transformation processes [19][20][21] and plasma assisted vapor liquid-solid growth [22,23].…”

Section: Introductionmentioning

confidence: 99%

“…Whereas synthesis methods are progressing towards the growth of extended hexagonal-type structures [15], 2H and 3C domains still coexist within a sub-micrometric scale in current samples. Furthermore, twin boundaries and more extended stacking faults in diamond-like crys-tals are hexagonal crystal inclusions with a thickness of only few atomic planes.…”

Section: Introductionmentioning

confidence: 99%

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Extrinsic Doping in Group IV Hexagonal-Diamond-Type Crystals

2020

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Over the last few years, group IV hexagonal-diamond type crystals have acquired great attention in semiconductor physics thanks to the appearance of novel and very effective growth methods. However, many questions remain unaddressed on their extrinsic doping capability and on how it compares to those of diamond-like structures. This point is here investigated through numerical simulations conducted in the framework of the Density Functional Theory (DFT). The comparative analysis for group III and V dopant atoms shows that: i) in diamond-type crystals the bulk sites symmetry (T d) is preserved by doping while in hexagonal crystals the impurity site moves towards a higher (T d) or lower (C3v) symmetry configuration dependently on the valence of the dopant atoms; ii) for Si and Ge, group III impurities can be more easily introduced in the hexagonaldiamond phase-whose local C3v symmetry better accommodates the threefold coordination of the impurity-while n-type impurities do not reveal any marked phase preference; iii) for C, both n and p dopants are more stable in the hexagonal-diamond structure than in the the cubic one, but this tendency is much more pronounced for n-type impurities.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Extrinsic Doping in Group IV Hexagonal-Diamond-Type Crystals

2020

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“… 30 , 31 Growth methods and critical growth constraints for the growth of Ge 1– x Sn x nanowires are detailed in a couple of recent reviews. 32 , 33 However, in most of these growth methods, Sn incorporation in the alloy nanowire is limited to below 10 atom %. In a significant development, Seifner et al reported the synthesis of high Sn content Ge 1– x Sn x nanowires ( x ≈ 0.19) via a chemical vapor deposition approach.…”

Section: Introductionmentioning

confidence: 99%

Stretching the Equilibrium Limit of Sn in Ge_1–xSn_x Nanowires: Implications for Field Effect Transistors

Biswas

Doherty

Galluccio

et al. 2021

ACS Appl. Nano Mater.

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Ge 1– x Sn x nanowires incorporating a large amount of Sn would be useful for mobility enhancement in nanoelectronic devices, a definitive transition to a direct bandgap for application in optoelectronic devices and to increase the efficiency of the GeSn-based photonic devices. Here we report the catalytic bottom-up fabrication of Ge 1– x Sn x nanowires with very high Sn incorporation ( x > 0.3). These nanowires are grown in supercritical toluene under high pressure (21 MPa). The introduction of high pressure in the vapor–liquid–solid (VLS) like growth regime resulted in a substantial increase of Sn incorporation in the nanowires, with a Sn content ranging between 10 and 35 atom %. The incorporation of Sn in the nanowires was found to be inversely related to nanowire diameter; a high Sn content of 35 atom % was achieved in very thin Ge 1– x Sn x nanowires with diameters close to 20 nm. Sn was found to be homogeneously distributed throughout the body of the nanowires, without apparent clustering or segregation. The large inclusion of Sn in the nanowires could be attributed to the nanowire growth kinetics and small nanowire diameters, resulting in increased solubility of Sn in Ge at the metastable liquid–solid interface under high pressure. Electrical investigation of the Ge 1– x Sn x ( x = 0.10) nanowires synthesized by the supercritical fluid approach revealed their potential in nanoelectronics and sensor-based applications.

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“…Quantum confinement effect was evidenced in small Ge and GeSi NCs 16 – 18 , enabling bandgap engineering along with composition 19 , shape 20 and strain 21 , 22 leading to tuning of optical and photoelectrical properties of NCs.…”

Section: Introductionmentioning

confidence: 99%

Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals

Cojocaru

Lepadatu

Nemneş

et al. 2021

Sci Rep

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We present a detailed study regarding the bandgap dependence on diameter and composition of spherical Ge-rich GexSi1−x nanocrystals (NCs). For this, we conducted a series of atomistic density functional theory (DFT) calculations on H-passivated NCs of Ge-rich GeSi random alloys, with Ge atomic concentration varied from 50 to 100% and diameters ranging from 1 to 4 nm. As a result of the dominant confinement effect in the DFT computations, a composition invariance of the line shape of the bandgap diameter dependence was found for the entire computation range, the curves being shifted for different Ge concentrations by ΔE(eV) = 0.651(1 − x). The shape of the dependence of NCs bandgap on the diameter is well described by a power function 4.58/d1.25 for 2–4 nm diameter range, while for smaller diameters, there is a tendency to limit the bandgap to a finite value. By H-passivation of the NC surface, the effect of surface states near the band edges is excluded aiming to accurately determine the NC bandgap. The number of H atoms necessary to fully passivate the spherical GexSi1−x NC surface reaches the total number atoms of the Ge + Si core for smallest NCs and still remains about 25% from total number of atoms for bigger NC diameters of 4 nm. The findings are in line with existing theoretical and experimental published data on pure Ge NCs and allow the evaluation of the GeSi NCs behavior required by desired optical sensor applications for which there is a lack of DFT simulation data in literature.

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Metastable Group IV Allotropes and Solid Solutions: Nanoparticles and Nanowires

Cited by 27 publications

References 594 publications

Extrinsic Doping in Group IV Hexagonal-Diamond-Type Crystals

Extrinsic Doping in Group IV Hexagonal-Diamond-Type Crystals

Stretching the Equilibrium Limit of Sn in Ge_1–xSn_x Nanowires: Implications for Field Effect Transistors

Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals

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Metastable Group IV Allotropes and Solid Solutions: Nanoparticles and Nanowires

Cited by 27 publications

References 594 publications

Extrinsic Doping in Group IV Hexagonal-Diamond-Type Crystals

Extrinsic Doping in Group IV Hexagonal-Diamond-Type Crystals

Stretching the Equilibrium Limit of Sn in Ge1–xSnx Nanowires: Implications for Field Effect Transistors

Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals

Contact Info

Product

Resources

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Stretching the Equilibrium Limit of Sn in Ge_1–xSn_x Nanowires: Implications for Field Effect Transistors