Galvanic Deposition of Nanoporous Si onto 6061 Al Alloy from Aqueous HF

Krishnamurthy, Aarti; Rasmussen, Don H.; Suni, Ian Ivar

doi:10.1149/1.3521290

Cited by 16 publications

(20 citation statements)

References 34 publications

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“…23 Although thick (12 m) Si films could be grown fairly rapidly, these Si deposits contained nanoscale pores ranging in size from 3-8 nm. 23 The nanoporous Si film appeared dark grey in solution, but gradually changed color to light grey and then white upon overnight exposure to laboratory air. This is consistent with the known color change expected with oxidation of Si to SiO 2 .…”

Section: Resultsmentioning

confidence: 99%

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Aqueous, Room Temperature Electrochemical Deposition of Compact Si Films

Krishnamurthy

Rasmussen

Suni

2011

Electrochem. Solid-State Lett.

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We report room temperature deposition of compact Si films onto 6061 Al alloy from aqueous solutions containing 10 mM HF and 20 mM Na 2 SiF 6 in 80 wt % formic acid (HCO 2 H) by a combination of galvanic and electroless deposition. Deposition for 30 h. yields a 7-10 m thick, dark grey Si thin film that does not change color upon exposure to air. Elemental analysis demonstrates that the as-deposited film contains 2-3 atom % Al, 4-5 atom % Cu, and 92-94 atom % Si. We believe that this is the first report of aqueous, room temperature deposition of thick, compact Si films.

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Section: Resultsmentioning

confidence: 99%

“…23 While 12 m thick nanoporous Si films were grown from a mild solution, compact Si films could not be obtained. Here we report electrochemical deposition of thick, compact Si films from HF-containing electrolytes in 80 wt % formic acid (HCO 2 H) by a combination of galvanic and electroless deposition.…”

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confidence: 99%

Aqueous, Room Temperature Electrochemical Deposition of Compact Si Films

Krishnamurthy

Rasmussen

Suni

2011

Electrochem. Solid-State Lett.

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“…These results are in contrast to galvanic Si deposition atop Al, which was only successful on Al alloy substrates, not on pure Al. 14,15 Conclusions Galvanic deposition of Mo onto 6061 Al alloy from solutions containing 1 mM HNO 3 , and 10 mM MoCl 5 allows growth of 9 μm thick Mo films after 40 min. of deposition.…”

Section: Methodsmentioning

confidence: 97%

“…The Mo film composition can be compared to that reported recently for a similar process, galvanic deposition of Si onto Al 6061 alloy. 14,15 In both cases, the Mo (Si) deposit contains substantial Al, since the dissolving Al from reaction 2 above must be transported through the growing Mo (Si) film, during which some Al is incorporated.…”

Section: Methodsmentioning

confidence: 99%

Galvanic Deposition of Mo Atop Al 6061 Alloy

Falola

Krishnamurthy

Radhakrishnan

et al. 2013

ECS Electrochemistry Letters

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We report galvanic deposition of Mo films onto 6061 Al alloy from aqueous solutions containing 1 mM HNO 3 and 10 mM MoCl 5 . Deposition for 40 min. yields an 9 μm thick Mo film, which also contains 18 atom% Al. The corrosion resistance of the Mo film is studied by voltammetry and electrochemical impedance spectroscopy in 0.5 M H 2 SO 4 and in 3.5 wt% NaCl electrolyte at pH 2, 7 and 12. These demonstrate that the galvanic Mo film significantly improves the corrosion resistance of the underlying Al 6061 substrate. Galvanic deposition appears to yield elemental, amorphous Mo films.Mo thin films have many technological applications, including back contacts for photovoltaic devices and corrosion-resistant coatings. 1,2 However, Mo thin film deposition currently requires expensive vacuum methods such as magnetron sputtering. 3 Electrochemical methods for thin film growth are often less expensive, easier to scale-up, and more amenable to high-volume manufacturing than vacuum methods. 4 Electrochemical deposition of refractory metals from aqueous electrolytes is difficult due to the relatively cathodic standard reduction potentials, multiple valence states, and complex oxy-anion solution phase chemistry. 5 Mo electrodeposition has been reported mainly from non-aqueous electrolytes such as high temperature molten salts. 6-8 More recently, Mo electrodeposition from aqueous electrolytes has also been reported, 9,10 but either without evidence for complete reduction to Mo(0), 9 or with extremely low current efficiency due to copious hydrogen evolution. 10 Mo alloys with a Mo content less than 50% can also be obtained from aqueous electrolytes. [11][12][13] We report galvanic deposition of compact Mo thin films onto Al 6061 alloy from a simple aqueous electrolyte. Energy dispersive X-ray spectroscopy (EDX) measurements indicate that these films contain primarily Mo and Al. These galvanic Mo films are also characterized by voltammetry and electrochemical impedance spectroscopy (EIS) in 0.5 M H 2 SO 4 and in 3.5 wt% NaCl electrolyte at pH 2, 7 and 12. ExperimentalConcentrated HNO 3 was obtained from J.T. Baker, MoCl 5 was obtained from Alfa Aesar, and 99.999% pure Al rod and 6061 Al foil (76 μm thick) were obtained from ESPI Metals. Al 6061 alloy typically contains 0.8-1.2 wt% Mg, 0.4-0.8 wt% Si, ≤ 0.70 wt% Mg, 0.15-0.40 wt% Cu, 0.04-0.35 wt% Cr, and smaller amounts of Mn, Ti, and Zn. Prior to Mo deposition, 6061 Al alloy was roughened with 150 grit Al 2 O 3 sandpaper and rinsed with water according to ASTM standard B253-11. MoCl 5 is corrosive and water-reactive, so it was stored under vacuum, and all experiments were performed in a chemical fume hood. All experiments were performed at room temperature (20 • C).Voltammetry and open circuit potential measurements were performed with an EG&G PAR model 273A potentiostat/galvanostat with an Al 6061 foil working electrode, Pt counter electrode, and SCE reference electrode. Electrochemical impedance spectroscopy (EIS) measurements were performed with a Solartron 1250 frequency respo...

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“…For virtually all top-down techniques, the porous silicon created is polycrystalline. For some bottom-up techniques such as sputtering/ dealloying (Fukatani et al 2005), electrodeposition (Krishnamurthy et al 2011),…”

Section: Specific Fabrication Techniquesmentioning

confidence: 99%

Routes of Formation for Porous Silicon

Canham

2014

Handbook of Porous Silicon

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Galvanic Deposition of Nanoporous Si onto 6061 Al Alloy from Aqueous HF

Cited by 16 publications

References 34 publications

Aqueous, Room Temperature Electrochemical Deposition of Compact Si Films

Aqueous, Room Temperature Electrochemical Deposition of Compact Si Films

Galvanic Deposition of Mo Atop Al 6061 Alloy

Routes of Formation for Porous Silicon

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