Electrochemical nanostructures: finishing and characterization

Vlad Shershulsky’s background

Anodizing

Anodizing – electrochemical metal or semiconductor treatment process invoking surface electrolytic oxidation and etching.

G. Wood, J. O’Sullivan, B. Vaszko,

J.Electrochem.Soc.115 (1968) 618

Fundamental

Beautiful example of synergetic self-organization in an open system far from thermodynamic equilibrium – from plain surface without any distinguished size to spatial pattern formation

Wehrspohn R., Nielsch K., Birner A., Schilling J., Muller F., Li A.

http://www.mpi-halle.mpg.de/mpi/publi/pdf/939_01.pdf

Applied: cornerstone of nanotechnology

• Photonic crystals

• Light emitters

• Nanotube fabrication templates

• Drag delivery nano-containers

• Bio-compatible implants

• Membranes

• Catalysts

• Surface protectors

• Micro-Assemblies

• And more…

Choi J., Sauer G., Nielsch K.,

Wehrspohn R., Gösele U.,

Chem. Mater., 15 (2003) 776

A. Birner, A. P. Li, F. Müller, U. Gösele, P. Kramper, V. Sandoghdar, J. Mlynek, K. Busch, V. Lehmann. Mater. Sci. Semicond. Proc. 3 (2000) 487–491

Xianglong Zhao et all.http://www.nature.com/srep/2013/130719/srep02238/full/srep02238.html

Matsumoto F., Kamiyama M.,

Nishio K., Masuda, H. Jpn. J.

Appl. Phys., 44 (2005) L355

Some results: pore size

Parkhutik V., Shershulsky V.

Theoretical modelling of porous oxide

growth on aluminium. – J. Phys. D:

Appl. Phys. 25 (1992) 1258 - 1263.

Going further: unified model and stability analyses

Boundary dynamics for non-equilibrium open system

and analogy with hydrodynamics

Continuity equation 𝛻2𝜑 = 0

Integral Bernoulli-Coochie 𝜑𝑡 + 𝑉 𝛻𝜑 2 = 𝑃0− 𝑃

Kinematic boundary

condition𝑓𝑡 + 𝑉 𝛻𝑓 ∙ 𝛻𝜑 = 0

Dynamic boundary

condition

𝜑 = 0or

𝜑𝑡 + 𝑉 𝛻𝜑 2 = 0

Internal boundary dynamics for linear stability analyses

𝑦 = 𝜂(𝑥1, 𝑥2), 𝜙 = 𝜑0+ 𝐸0𝑦

𝜑𝑡 + 𝑉 𝛻𝜑 2 = 𝑃0− 𝑃

𝜙 = 𝜙0 exp 𝑖 𝑘1𝑥1+ 𝑘2𝑥2 + 𝜇𝑦 + 𝜈𝑡η = 𝜂0 exp 𝑖 𝑘1𝑥1+ 𝑘2𝑥2 + 𝜈𝑡

𝜇 = (𝑘12 + 𝑘2

2)1/2

𝜈 = 𝜇𝐸0𝑑

𝑑𝐸𝑉𝐸 |𝐸=𝐸0

When plain oxide reaches critical

thickness 𝐿∗ = 𝑈/𝐸∗ flat boundary

stability breaks

𝑑

𝑑𝐸𝑉𝐸 |𝐸=𝐸0 = 0

for all spatial wavelengths

simultaneously, which leads to short

length noise growth (pore nucleation),

followed by the stage of self-

organization with specific

characteristic spatial size / dimension. Parkhutik V., Shershulsky V. Theoretical modelling

of porous oxide growth on aluminium. – J. Phys.

D: Appl. Phys. 25 (1992) 1258 - 1263.

Furneaux R., Rigby

W., Davidson A. The

formation of

controlled-porosity

membranes from

anemically oxidized

aluminium. Nature

337 (1989), 147

Shershulsky V., Parkhutik V., Makushok

Y., Yakovlev D. Novel methods of

boundary fractal dynamics:

development and practical

applications. Final report F12-059 to

Fundamental Research Foundation. –

Minsk, Belarus (1992) 204 pp.

Numerical simulation: self-organization and transition effects

Lancerotti L., Brown W.,

Poate J., Augustyniak W.,

Nucleation and groth of

porous anodic films on

aluminiumNature 272

(1978), 433 Shershulsky V., Ph.D. Thesis (1992)

Chen Shuoshuo, Ling Zhiyuan,

Hu Xing, Yang Huia, Li Yia. J.

Mater. Chem., 20 (2010) 1794

S. Ronnebeck S., Carstensen

S., Ottow S., Föll H. J POROUS

MA, 7(1-3) (2000) 353

Numerical simulation: porous boundary properties

2D cellular automata

numerical solution for

system of nonlinear

special differential

equations with moving

boundaries

Shershulsky V., Parkhutik V., Makushok Y.,

Yakovlev D. Novel methods of boundary

fractal dynamics: development and practical

applications. Final report F12-059 to

Fundamental Research Foundation. – Minsk,

Belarus (1992) 204 pp. (in Russian)

Shershulsky V., Ph.D Thesis (1992)

Parkhutik V., Albella J., Martinez-Duart J.

Gomez-Rodrigues J., Baro A., Shershulsky V.

Different types of pores in porous silicon. –

Appl.Phys.Let. 62 (1993) 366 – 368

Hidetsugu Sakaguchi and Jie Zhao.

Phys. Rev. E 81 (2010) 031603

Cheng C., Ng K., Aluru N., Ngan A. J.

Appl. Phys. 113 (2013) 204903

Some prospects

• 3D simulation. Surprisingly still not accomplished.

• More realistic models, taking into account surface states, field effects, space charge, internal stress, and viscosity.

• Quantum electrochemistry of curved surface and quantum ballistic model.

• Computational optics of electrochemically treated surface.

• Molecular transport in pore systems and gas- and hydrodynamics at nano-scale.

• CAD-ready design and simulation software modules.

• Experimental and production ready fabrication processes tuning.

Summary

Porous nature of anodic aluminum oxide was determined in early 50-th.

Anodizing draw even more attention in 90-th with demonstration of efficient visible light emission from porous silicon. Pore formation and surface self-organization formed one of the first and the most important branches of contemporary nanotechnology.

I was fortunate to serve as a theorist in one of the most active research groups in this field, to propose model of pore formation currently in wide use, to explain linear dependence of pore size on anodizing potential, and to make first successful computer simulations of pore growth.

Surface nano-electrochemistry remains the area of active research and the source of new technologies. Recent results reported by various groups in 2010+ share many of our approaches and confirm most of our main findings.

And that is not the only area of my interests in R&D

ThanksVladislav Shershulsky

+7 903 7980571

vladsh@microsoft.com

shershulskyvi@yandex.ru