Epitaxial diamond-hexagonal silicon nano-ribbon growth on (001) silicon

Qiu, Yu; Bender, Hugo; Richard, Olivier; Kim, M.-S.; Besien, Els Van; Vos, Ingrid; Broeck, M. de Potter de ten; Mocuta, D.; Vandervorst, Wilfried

doi:10.1038/srep12692

Cited by 32 publications

(23 citation statements)

References 31 publications

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“…1 NWs also allow for the existence of crystal phases that do not even exist in the bulk counterpart. 2,3 Besides non-nitride III-V materials, Si 4,5,6,7,8,9 and Ge 10,11,12 in the NW form can exist in the hexagonal 2H phase (properly named as lonsdaleite), which in the bulk is hardly obtained (usually under high pressure conditions). 13,14 The formation of NWs with hexagonal crystal symmetry has attracted enormous interest among researchers.…”

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confidence: 99%

Crystalline, Phononic, and Electronic Properties of Heterostructured Polytypic Ge Nanowires by Raman Spectroscopy

et al. 2018

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Semiconducting nanowires (NWs) offer the unprecedented opportunity to host different crystal phases in a nanostructure, which enables the formation of polytypic heterostructures where the material composition is unchanged. This characteristic boosts the potential of polytypic heterostructured NWs for optoelectronic and phononic applications. In this work, we investigate cubic Ge NWs where small (∼20 nm) hexagonal domains are formed due to a strain-induced phase transformation. By combining a nondestructive optical technique (Raman spectroscopy) with density-functional theory (DFT) calculations, we assess the phonon properties of hexagonal Ge, determine the crystal phase variations along the NW axis, and, quite remarkably, reconstruct the relative orientation of the two polytypes. Moreover, we provide information on the electronic band alignment of the heterostructure at points of the Brillouin zone different from the one (Γ) where the direct band gap recombination in hexagonal Ge takes place. We demonstrate the versatility of Raman spectroscopy and show that it can be used to determine the main crystalline, phononic, and electronic properties of the most challenging type of heterostructure (a polytypic, nanoscale heterostructure with constant material composition). The general procedure that we establish can be applied to several types of heterostructures.

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confidence: 99%

Crystalline, Phononic, and Electronic Properties of Heterostructured Polytypic Ge Nanowires by Raman Spectroscopy

et al. 2018

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“…[6][7][8] Nevertheless, in group IV nanowires, the stability of novel polytypes -previously theoretically predicted 9 but experimentally observed only very locally in the form of crystal imperfections [10][11][12][13] is now supported by clear experimental evidences. [14][15][16][17][18][19] For instance, Vincent et al 14 reported the synthesis of quasi-periodic allotrope Ge heterostructures of hexagonal-diamond (wurtzite structure with single atom type) and cubic-diamond domains. These systems were obtained by a straininduced phase transformation in which size effects (in particular the preferential nucleation of dislocations on the wire surface and the activation of unusual slip planes) play a crucial role by lowering the value of the stress required by the cubic to hexagonal transition.…”

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confidence: 99%

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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“…At the given oxidation temperature, the oxide is not viscous and is therefore not pushed upwards out of the trench. Hence, the volume expansion leads to a lateral force on the fin sidewalls, [20] leading to a compression of the fins' transverse inplane lattice parameter. In Figure 11 (after STI) one can also identify a bump around À500arcsec which is not related to the multilayer structure but represents compressively strained Si located at the lower part of the fin (below the multilayer structure).…”

Section: Etched Multilayer Finsmentioning

confidence: 99%

Strain and Compositional Analysis of (Si)Ge Fin Structures Using High Resolution X‐Ray Diffraction

Schulze

Loo

Witters

et al. 2017

physica status solidi c

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The performance of heterogeneous 3D transistor structures critically depends on the composition and strain state of the buffer, channel, and source/drain regions. In this paper we discuss the value of in‐line high resolution X‐ray diffraction (HRXRD) measurements based on three representative examples. First, we analyzed the strain state of etched Ge fins in the two in‐plane directions. We could verify a loss in channel strain after growth of a Si cap which we attribute to Ge reflow. Secondly, we studied the composition and strain state of relaxed SiGe fins selectively grown in an STI matrix where we found an anisotropic in‐plane strain state with significantly reduced relaxation in the direction along the fin. Finally, we used HRXRD for the analysis of complex multilayer fin structures which are relevant for horizontal nanowire FETs that are candidates to replace FinFETs below the 7 nm technology node. With this example we could demonstrate that HRXRD is capable of providing insight into fin stress created by interlayer dielectrics (ILD0).

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Epitaxial diamond-hexagonal silicon nano-ribbon growth on (001) silicon

Cited by 32 publications

References 31 publications

Crystalline, Phononic, and Electronic Properties of Heterostructured Polytypic Ge Nanowires by Raman Spectroscopy

Crystalline, Phononic, and Electronic Properties of Heterostructured Polytypic Ge Nanowires by Raman Spectroscopy

Crystal Phase Effects in Si Nanowire Polytypes and Their Homojunctions

Strain and Compositional Analysis of (Si)Ge Fin Structures Using High Resolution X‐Ray Diffraction

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