Epitaxial Post-Implant Recrystallization in Germanium Nanowires

Kelly, Róisín A.; Liedke, Bartosz; Baldauf, S.; Gangnaik, Anushka S.; Biswas, Subhajit; Georgiev, Yordan M.; Holmes, Justin D.; Posselt, M.; Petkov, Nikolay

doi:10.1021/acs.cgd.5b00836

Cited by 9 publications

(12 citation statements)

References 58 publications

(139 reference statements)

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“…The use of nanostructured materials such as nanowires in semiconductor devices offers the possibility of satisfying or even surpassing Moore's Law and, in this context, single-crystal Ge nanowires offer considerable advantages [1], [2]. Specifically, compared to Si, its larger exciton Bohr radius (to facilitate quantum confinement), its lower temperature of recrystallization (to help reduce thermal budgets) and the higher mobility of its charge carriers (for improved device performance) make single-crystal Ge nanowires promising potential components for the next generation of field-effect transistors [1]- [5].…”

Section: Introductionmentioning

confidence: 99%

“…Specifically, compared to Si, its larger exciton Bohr radius (to facilitate quantum confinement), its lower temperature of recrystallization (to help reduce thermal budgets) and the higher mobility of its charge carriers (for improved device performance) make single-crystal Ge nanowires promising potential components for the next generation of field-effect transistors [1]- [5].…”

Section: Introductionmentioning

confidence: 99%

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Effects of temperature on the ion-induced bending of germanium and silicon nanowires

Camara

Hanif

Tunes

et al. 2017

Mater. Res. Express

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Nanowires can be manipulated using an ion beam via a phenomenon known as ion-induced bending (IIB). While the mechanisms behind IIB are still the subject of debate, accumulation of point defects or amorphisation are often cited as possible driving mechanisms. Previous results in the literature on IIB of Ge and Si nanowires have shown that after irradiation the aligned nanowires are fully amorphous. Experiments were recently reported in which crystalline seeds were preserved in otherwise-amorphous ion-beam-bent Si nanowires which then facilitated solid-phase epitaxial growth (SPEG) during subsequent annealing. However, the ion-induced alignment of the nanowires was lost during the SPEG. In this work, in situ ion irradiations in a transmission electron microscope at 400°C and 500°C were performed on Ge and Si nanowires, respectively, to supress amorphisation and the build-up of point defects.Both the Ge and Si nanowires were found to bend during irradiation thus drawing into question the role of mechanisms based on damage accumulation under such conditions. These experiments demonstrate for the first time a simple way of realigning single-crystal Ge and Si nanowires via IIB whilst preserving their crystal structure.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of temperature on the ion-induced bending of germanium and silicon nanowires

Camara

Hanif

Tunes

et al. 2017

Mater. Res. Express

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“…However, ion implantation damages the Ge crystal [11,12]. This creates the need for a high temperature treatment to anneal out the defects and recrystallize Ge [13][14][15][16]. A high heating rate can induce structural damage while a low annealing time might not fully crystallize the implanted region, resulting in defect formation that will affect the junction leakage current [17].…”

Section: Introductionmentioning

confidence: 99%

Selective Epitaxial Growth of In Situ Doped SiGe on Bulk Ge for p+/n Junction Formation

et al. 2020

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Epitaxial in situ doped Si0.73Ge0.27 alloys were grown selectively on patterned bulk Ge and bulk Si wafers. Si0.73Ge0.27 layers with a surface roughness of less than 3 nm were demonstrated. Selectively grown p+Si0.73Ge0.27 layers exhibited a resistivity of 3.5 mΩcm at a dopant concentration of 2.5 × 1019 boron atoms/cm3. P+/n diodes were fabricated by selectively growing p+- Si0.73Ge0.27 on n-doped bulk Ge and n-doped Si wafers, respectively. The geometrical leakage current contribution shifts from the perimeter to the bulk as the diode sizes increase. Extracted near midgap activation energies are similar to p+/n Ge junctions formed by ion implantation. This indicates that the reverse leakage current in p+/n Ge diodes fabricated with various doping methods, could originate from the same trap-assisted mechanism. Working p+/n diodes on Ge bulk substrates displayed a reverse current density as low as 2.2·10−2 A/cm2 which was found to be comparable to other literature data. The layers developed in this work can be used as an alternative method to form p+/n junctions on Ge substrates, showing comparable junction leakage results to ion implantation approaches.

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“…[6], [11] However, if an implanted single-crystal suffers amorphisation due to the ion irradiation then a residual crystalline seed is required to enable its recovery via solid-phase epitaxial growth (SPEG). [6], [12]- [14] Although ion implantation and subsequent recrystallisation via SPEG are well-established techniques in the processing of silicon, when studied in nanostructures significant differences have been observed compared to the bulk. [5], [6], [11], [12], [14] For instance, different SPEG recrystallisation activation energies and/or altered damage profiles have been reported.…”

Section: Introductionmentioning

confidence: 99%

“…[6], [12]- [14] Although ion implantation and subsequent recrystallisation via SPEG are well-established techniques in the processing of silicon, when studied in nanostructures significant differences have been observed compared to the bulk. [5], [6], [11], [12], [14] For instance, different SPEG recrystallisation activation energies and/or altered damage profiles have been reported. [12], [15] The phenomenon of ion-induced bending (IIB) has been observed where nanostructures such as cantilevers, [16], [17] nanotubes [18] or nanowires [19]- [25] suffer plastic deformation under irradiation.…”

Section: Introductionmentioning

confidence: 99%

Shape Modification of Germanium Nanowires during Ion Irradiation and Subsequent Solid‐Phase Epitaxial Growth

Camara

Hanif

Tunes

et al. 2018

Adv Materials Inter

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During ion irradiation which is often used for the purposes of band gap engineering, nanostructures can experience a phenomenon known as ion-induced bending (IIB). The mechanisms behind this permanent deformation are the subject of debate. In this work, germanium nanowires are irradiated with 30 or 70 keV xenon ions to induce bending either away from or towards the ion beam. By comparing experimental results with Monte-Carlo calculations, the direction of the bending is found to depend on the damage profile over the cross-section of the nanowire. After irradiation, the nanowires are annealed at temperatures up to 440°C triggering solid-phase epitaxial growth (SPEG) causing further modification to the deformed nanowires. After IIB, it is observed that nanowires which had bent away from the ion beam then straighten during SPEG whilst those which had bent towards the ion beam bend even more. This is attributed to differences in the mechanisms responsible for the ion-beam-induced bending in opposite directions. Thus, the results reported here give insights into the mechanisms causing the IIB of nanowires and demonstrate how to predict the evolution of nanowires under irradiation and annealing. Finally, they show that, under certain conditions, the bending can even be removed via SPEG.

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Epitaxial Post-Implant Recrystallization in Germanium Nanowires

Abstract: As transistor dimensions continue to diminish, techniques for fabrication need to be adapted. In particular, crystal recovery post ion implantation is required due to destructive ion bombardment inducing crystal damage including amorphisation. Here, we report a study on the

Cited by 9 publications

References 58 publications

Effects of temperature on the ion-induced bending of germanium and silicon nanowires

Effects of temperature on the ion-induced bending of germanium and silicon nanowires

Selective Epitaxial Growth of In Situ Doped SiGe on Bulk Ge for p+/n Junction Formation

Shape Modification of Germanium Nanowires during Ion Irradiation and Subsequent Solid‐Phase Epitaxial Growth

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