Presentation on theme: "Langmuir – Blodgett film"— Presentation transcript:
1 Langmuir – Blodgett film Sloviková AlexandraZajíčková Michaela
2 History 17th century First discovery of optic efect 19th century The beginning of preparation of the thin layers20th century (70th years)The expansion of plasma technologies20th century (80th years)Development of Lamgmuir – Blodgett films
3 Why study molecular orientation in thin films? interfacial properties(optical, electronic and mechanical)molecular interactionsorganizational model for complex systemsPhotoresist“Chemically” cleanedsilicon waferSilicon oxide “barrier”layer
4 IntroductionLangmuir – Blodgett films are monofilms or multifilms on solid substrate.Molecules form a monolayer at the interface air-liquidThey are nanomaterialsThe films are layers at scale 0,1 – 0,001 nm~ 1 nm
5 Monolayer PhasesWhen the molecules are first spread on the water surface, they are loosely packed and form a so-called 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 liquid-solid phase transition.Molecular area (nm2/molecule)Surface pressure (mN/m)Gas phaseLiquid phaseSolid phase
6 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.
7 Characteristics of substrate Hydrophilic:GlassAluminium, chromium,WaferHydrophobic:trimethylchlorsilane
8 Film transfer Water subphase Vertical Horizontal This technique is actual for highly hydrophobic molecules.HorizontalThis technique is suitable for transfer of very stif films.
9 Langmuir – Blodgett films Vertically prepared films3 types:repeated submergence – type Xrepeated emergence – type Zswitching both types – type YXZY