Nanostructural Transformation and Formation of Heterojunctions from Si Nanowires

Wong, Tailun; Cheng, Chun; Li, Wei; Fung, Kwok Kwong; Wang, Naiyan

doi:10.1021/nn100465s

Cited by 10 publications

(11 citation statements)

References 28 publications

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“…Therefore, a preliminary growth mechanism for the nickel silicide nanostructures can be proposed. It has been well accepted that the temperature and the pressure of the reaction precursor are the key factors affecting the formation of metallic silicide [23][24][25][26]. In our synthesis, when the gas ratio of SiH 4 and H 2 is fixed at 80:80 (sccm), Ni 2 Si, Ni 3 Si 2 , and NiSi NWs are successfully synthesized at the temperature of 450, 500, and 600 8C, respectively.…”

Section: Resultsmentioning

confidence: 86%

Phase-controlled synthesis of nickel silicide nanostructures

Fan¹,

Zhang²,

Du³

et al. 2012

Materials Research Bulletin

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Section: Resultsmentioning

confidence: 86%

Phase-controlled synthesis of nickel silicide nanostructures

Fan¹,

Zhang²,

Du³

et al. 2012

Materials Research Bulletin

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“…[273][274][275][276] Until around 2010, most of PEC cells focused on the solar cell application using redox electrolytes, such as HBr/Br 2 [277] and Fe(CN) 6 4− /Fe(CN) 6 3− . [278] To protect the surface of SiNWs, methylation, [279] carbon nanotubes, [280] and double-walled carbon nanotubes [281] have been applied. To enhance the cell performance, Pt nanoparticles have been decorated on SiNWs, [279,282] which leads to ≈8% of conversion efficiency.…”

Section: Photoelectrochemical Solar Cells and Photoelectrocatalysismentioning

confidence: 99%

“…[278] To protect the surface of SiNWs, methylation, [279] carbon nanotubes, [280] and double-walled carbon nanotubes [281] have been applied. To enhance the cell performance, Pt nanoparticles have been decorated on SiNWs, [279,282] which leads to ≈8% of conversion efficiency. To minimize the photocorrosion of SiNW in aqueous electrolytes, ionic liquid has also been used as electrolyte, which has yielded long-term stability.…”

Section: Photoelectrochemical Solar Cells and Photoelectrocatalysismentioning

confidence: 99%

“…To minimize the photocorrosion of SiNW in aqueous electrolytes, ionic liquid has also been used as electrolyte, which has yielded long-term stability. [279] After the ≈2010, the research on PEC cells using SiNWs as photoelectrodes has shifted toward the generation of hydrogen by water splitting, that is, photoelectrocatalysis. Similar to the case of PEC solar cells, researches have been focused on the protection, [273] enhancing catalytic activity by incorporating cocatalysts and the application of dual semiconductor configuration.…”

Section: Photoelectrochemical Solar Cells and Photoelectrocatalysismentioning

confidence: 99%

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Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

Srivastava

Khang

2021

Advanced Materials

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classified into two common approaches: bottom-up chemical synthesis, such as vapor-liquid-solid growth, [16][17][18][19][20] and topdown fabrication schemes. [21][22][23] This review will focus on the top-down fabrication of Si structures using a wet chemical etching technique aided with a metal catalyst, called metal-assisted chemical etching (MaCE). [24][25][26][27][28][29][30][31][32] In comparison with top down fabrication methods based on dry etching using a reactive plasma in vacuum, MaCE is less expensive and less complex. [33][34][35] MaCE is a nano-scale reductionoxidation (redox) process that usually occurs in aqueous solution where the sample to be etched is in contact with the etchant. MaCE is a simple, cost-effective, and versatile method to produce Si nanostructures; due to these attractive features, there have been many good review articles published on the process. [36][37][38][39][40][41][42] With two-decades of research of the MaCE and its innovative variations, recent studies have focused on the various applications of Si nanostructures prepared by MaCE, including photovoltaics, [43,44] thermoelectrics and piezoelectric nanogenerators, [45] energy storage, [46][47][48] nanophotonics and optoelectronics, [49] and biosensors and biomedical applications. [50][51][52] In this review, we provide an overview of the recent advances in MaCE processes and their novel applications. To differentiate this review from previous review articles, the main emphasis is on the recently developed novel MaCE processes and the macroscale structuring of Si by MaCE. We begin the review by describing new MaCE processes, particularly catalysts for MaCE. In contrast to well-known noble metal catalysts, such as Ag, Au, and Pt, carbon-based catalysts, such as graphene, graphene oxide, and carbon nanotubes, have been successfully applied as catalysts for MaCE. In addition, TiN has been found to be a catalyst for MaCE, making the whole process CMOS-compatible. Different types of etch additives, such as various alcohols and chlorides, have also been discussed, which enhance etch uniformity by increasing the wettability of etchants and suppressing the random diffusion of excessive (holes) h + by trapping them for better etch control. Recent novel variations of the MaCE process have been introduced, such as MaCE with externally applied electric or magnetic fields. The external field has a profound effect on the output of MaCE, by controlling the etch directionality and etch rate. In addition, MaCE can be combined with unconventional patterning techniques, StructuringSi, ranging from nanoscale to macroscale feature dimensions, is essential for many applications. Metal-assisted chemical etching (MaCE) has been developed as a simple, low-cost, and scalable method to produce structures across widely different dimensions. The process involves various parameters, such as catalyst, substrate doping type and level, crystallography, etchant formulation, and etch additives. Careful optimization of these parameters is the key to the succe...

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“…[11][12][13] The epitaxial layer-by-layer growth of CoSi 2 along the Si NW axis was observed, which was explained by the limited supply of Co atoms due to point contact. 12 In that report, it was found that having a lower interface energy between the native oxide and Si than between native oxide and silicide prevented heterogeneous nucleation, resulting in homogeneous nucleation.…”

mentioning

confidence: 99%

Silicidation of Co/Si Core Shell Nanowires

Lee

Park

2012

J. Electrochem. Soc.

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The formation of CoSi 2 nanowires (NWs) via the annealing of Si NWs conformally coated with atomic layer deposited (ALD) Co layers was investigated. Co ALD was carried out using Co(iPr-AMD) 2 and NH 3 as a precursor and a reactant, respectively. Rapid thermal annealing (RTA) of Co/Si core-shell NWs produced Co oxide instead of CoSi 2 due to oxygen contamination during annealing. To prevent oxygen contamination, a highly conformal ALD Ru layer was used as a capping layer. X-ray diffraction showed the formation of CoSi 2 when the Co/Si core-shell NWs were annealed at over 800 • C. To investigate the deposition and silicidation process on a nanometer scale, high resolution C s -corrected scanning transmission electron microscopy was utilized with electron energy loss spectroscopy and energy dispersion spectroscopy. In contrast to previous reports on silicidation of NWs, the dominant diffusion species was found to be Si instead of Co based on a nucleation-controlled reaction.Silicides are important materials for contacts in modern Si devices due to their low contact resistance and good compatibility. Silicide is usually formed by metal deposition on a Si layer followed by annealing at the appropriate temperature through a solid-state reaction. 1 Recently, silicide nanowires (NWs) have attracted great attention since they have the high conductivity and compatibility with metal required for contacts in nanowire devices. Silicide NWs are usually synthesized by chemical vapor deposition (CVD). For instance, three kinds of cobalt silicide NWs, Co 2 Si, Co 3 Si, and CoSi, were synthesized by the reaction of CoCl 4 vapor and Si substrate. 2 Also, SiH 4 gas was reacted with Ni thin film to form NiSi NW. 3, 4 Similarly, several silicide NWs have been reported, such as TiSi

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Nanostructural Transformation and Formation of Heterojunctions from Si Nanowires

Cited by 10 publications

References 28 publications

Phase-controlled synthesis of nickel silicide nanostructures

Phase-controlled synthesis of nickel silicide nanostructures

Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

Silicidation of Co/Si Core Shell Nanowires

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