Transcript saska + misa2

Langmuir – Blodgett film
Sloviková Alexandra
Zajíčková Michaela
History
• 17th century
First discovery of optic efect
• 19th century
The beginning of preparation of the thin layers
• 20th century (70th years)
The expansion of plasma technologies
• 20th century (80th years)
Development of Lamgmuir – Blodgett films
Why study molecular orientation
in thin films?
• interfacial properties
(optical, electronic and mechanical)
• molecular interactions
• organizational model for complex
Photoresist
systems
“Chemically” cleaned
silicon wafer
Silicon oxide “barrier”
layer
Introduction
• Langmuir – Blodgett films are monofilms or
multifilms on solid substrate.
• Molecules form a monolayer at the interface airliquid
• They are nanomaterials
• The films are layers at scale 0,1 – 0,001 nm
~ 1 nm
• When the molecules are
first spread on the water
surface, they are loosely
packed and form a socalled gas phase.
• Increasing the surface
pressure translates as a
transition to a liquid phase.
• Further increases in
pressure bring about a last
compressibility change that
is associated to a liquidsolid phase transition.
Surface pressure (mN/m)
Monolayer Phases
Solid phase
Liquid phase
Gas phase
Molecular area (nm2/molecule)
• A barrier on the water surface pushes and
compacts the molecules.
• Spreading amphiphile molecules on a water
surface yields monolayers or films where the
hydrophobic segments stem at the water/air
interface.
• Films with tailored stability, orientation of
molecules or phase transition can thereby be
transferred to the substrate.
Characteristics of substrate
• Hydrophilic:
– Glass
– Aluminium, chromium,
– Wafer
• Hydrophobic:
– trimethylchlorsilane
Film transfer
Water
Water subphase
• Vertical
– This technique is actual for highly hydrophobic molecules.
• Horizontal
– This technique is suitable for transfer of very stif films.
Langmuir – Blodgett films
• Vertically prepared films
• 3 types:
– repeated submergence – type X
– repeated emergence – type Z
– switching both types – type Y
X
Z
Y
References
• [1] doc.RNDr. Vladimír Čech, Ph.D. Lectures
• [2] http://isi4.isiknowledge.com\portal.cgi
• [3] http://www.sciencedirect.com
• [4] http://google.com
• [5] http://nanotechnologweb.org