CRL 341 Experimental
Physical Chemistry I
CRL 103-104 Experimental
General Chemistry I-II
CHE433 Special Topics: Surface
Research Interests & Student Research
surface science /
reaction dynamics /
laser photochemistry /
laser-surface interactions /
physical chemistry /
Photochemical & Chemical Modification of Si and Porous Si
Electron transfer during metal-assisted and stain etching of silicon
Semicond. Sci. Technol. 31, 014002 (2016)
Irradiation with laser light fundamentally
alters the surface chemistry of silicon. For instance, whereas clean crystalline Si is virtually inert to aqueous hydrofluoric acid,
irradiation of a Si crystal immersed in HF(aq) with a cw visible laser can lead to
the formation of porous Si. Once formed, the reactivity of porous Si can also be altered by irradiation. We are studying these processes in order to determine what factors affect the photochemical
reactivity of Si surface and to develop a mechanistic understanding of the photochemical reactions involved. An example can be found here in J. Amer. Chem. Soc.
We have also extended this work to investigate the formation of porous silicon by purely chemical methods, so-called stain etching.
In stain etching an oxidant is mixed with fluoride to form an aqueous solution that spontaneously produces porous silicon once a silicon crystal has
been dipped in it. We are now investigating the role of the oxidant and how it can be used to control both the photoluminescence spectrum and the morphology of
the por-Si film. We have demonstrated that several ions work well, including Fe(III), Ce(IV) and IrCl62- and we now have a quantitative understanding of charge transfer in terms of Marcus theory. The V(V) ion
has been used to form uniform films that can be as much as 20 µm thick and well as por-Si powder in collaboration with Vesta Ceramics.
As described below, we make macroporous silicon (porous silicon with very large pores) by etching pillar-covered Si substrates in alkaline solutions.
For more on porous silicon click here.
Pillar Formation & Modification
Hexagonal macropore etched into pillar-covered Si crystal
Laser irradiation of semicondutors and metals, under the appropriate conditions can lead to the
spontaneous formation of conical structures.
When made with a femtosecond laser, these pillars can be ten or so micrometers long. The
tips, however, are on the order of a few hundred nanometers or less.
Using a nanosecond laser, the pillars are much larger, up to 100
µm or more and a few micrometers at their tip. We have shown
that we can make such pillars in silicon,
as well as titanium and a number of other metals including Zn, Sn and Ni.
We have used alkaline solutions (concentrated KOH or tetramethylammonium hydroxide, TMAH) to etch silicon pillars. Short
etching times produce sharpended pillars. When the pillars are overetched, they disappear leaving behind macropores that are several
micrometers wide, such as the hexagon shown left.
ZnO nanorods grown on a Zn laser ablation pillar
More on pillars and macropores can be found here.
Anodic Titania Nanotubes & Porous Alumina
This project involves electrochemically etching Ti or Al to created arrays of nanotubes or pores while simultaneously
oxidizing the metal to its oxide (titania, TiO2, or alumina, Al2O3). Read more about it here.
Dynamics of Adsorption and Desorption
|I have long studied the simplest of surface chemical reactions, the adsorption and thermal desorption of small molecules from surfaces,
particularly hydrogen on silicon.
I have also reviewed
stimulated desorption of hydrogen from silicon.
While this work has laid the foundation for much of my research, currently these are not the types of studies
that I'm performing in my lab in West Chester. Rather they are part of
what of do when I work with, for instance,
in Essen, Germany.|
|Read more about the my studies of surface dynamics here.
Solidification Driven Extrusion (Nanospikes)
|While making silicon and germanium pillars, we noticed that nanoscales spikes form atop the pillars. We subsequently showed that the same physics that is behind this phenomenon is also active in your freezer and can result in the formation of centimeter long ice
spikes. Read more about this here.
Ultrafast Surface Photochemistry in the VUV
|This was a project I worked on while at the University of Birmingham that involves the use of femtosecond pulsed lasers to create vacuum
ultraviolet photons via high harmonic generation.
Read more about it here.
Selected Recent Publications:
- Subtractive methods to form pyrite and sulfide nanostructures of Fe, Co, Ni, Cu and Zn,
Kurt W. Kolasinski, Current Op. Solid State Mater. Sci. (accepted).
- Electron transfer during Metal Assisted and Stain Etching of Silicon,
Kurt W. Kolasinski, Semicond. Sci. Technol. 31, 014002 (2016).
- The stoichiometry of metal assisted etching (MAE) of Si in V2O5 + HF and HOOH + HF solutions
Kurt W. Kolasinski, William B. Barclay, Yu Sun, and Mark Aindow, Electrochim. Acta, 158, 219–228 (2015).
- Bubbles: A review of their relationship to the formation of thin films and porous materials
Kurt W. Kolasinski, Mesoporous Biomater., 1, 49-60 (2014).
- Porous Silicon Formation by Stain Etching
Kurt W. Kolasinski, in Handbook of Porous Silicon, 2nd Edition, edited by Leigh T. Canham, (Springer Verlag, Berlin, 2014) pp. 35-48.
- Porous Silicon Formation by Galvanic Etching
Kurt W. Kolasinski, in Handbook of Porous Silicon, 2nd Edition, edited by Leigh T. Canham, (Springer Verlag, Berlin, 2014) pp. 23-33.
- The mechanism of Galvanic/Metal Assisted Etching of Silicon
Kurt W. Kolasinski, Nanoscale Res. Lett. 9, 432 (2014).
- Photochemical and Chemical Modification of Porous Silicon
Kurt W. Kolasinski, in Porous Silicon for Biomedical Applications, edited by Helder Santos and Laura Overend (Woodhead Publishing, Cambridge, UK, 2014) pp. 52-80.
- New Approaches to the Production of Porous Silicon by Stain Etching
Kurt W. Kolasinski,
in Nanostructured Semiconductors: from basic research to applications, edited by P. Granitzer and K. Rumpf
(Pan Stanford Publishing, Singapore, 2014) pp. 45-84.
- The Mechanism of Photo-Hydrosilylation on Silicon and Porous Silicon Surfaces
Kurt W. Kolasinski, J. Amer. Chem. Soc., 135, 11408-11412 (2013).
- The stoichiometry of Si electroless etching in V2O5 + HF solutions
Kurt W. Kolasinski and William B. Barclay, Angew. Chem. Int. Ed. Eng., 52, 6731-6734 (2013).
- A test of Marcus theory predictions for electroless etching of silicon
Kurt W. Kolasinski, Jacob W. Gogola and William B. Barclay, J. Phys. Chem C, 116, 21472-21481 (2012).
- Charge Transfer and Nanostructure Formation During Electroless Etching of Silicon
Kurt W. Kolasinski,
J. Phys. Chem. C 114, 22098-22105 (2010).
- Solid Structure Formation During the Liquid/Solid Phase Transition,
Kurt W. Kolasinski,
Curr. Op. Solid State & Mater. Sci., 11, 76-85 (2007).
- Catalytic growth of nanowires: Vapor-liquid-solid, vapor-solid-solid, solution-liquid-solid and solid-liquid-solid growth,
Kurt W. Kolasinski, Curr. Op. Solid State & Mater. Sci. 10, 182-191(2006)
- Silicon nanostructures from electroless electrochemical etching,
Kurt W. Kolasinski,
Curr. Op. Solid State & Mater. Sci. 9, 73-83 (2005).
For a nearly full list of publications click here.
K. W. Kolasinski, Physical Chemistry: How Chemistry Works. (John Wiley & Sons, Chichester, to be published 2016)
Kurt W. Kolasinski, Surface Science: Foundations of Catalysis and Nanoscience, 3rd Edition
( John Wiley & Sons
, Chichester, 2012).
Accompanying website for the book,
including the figures in pdf format, supplemental material and exercises.
For further information on related topics,
try these sites: