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Nanosphere Lithography

ramiro
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Nanosphere Lithography

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    1. Nanosphere Lithography Zunächst möchte ich ihnen eine Übersicht über meinen Vortrag gebenZunächst möchte ich ihnen eine Übersicht über meinen Vortrag geben

    2. Overview of my project

    3. Choosing and cleaning the substrate The mean surface corrugation should be much smaller than the particle diameter. glass plates; polished silicon wafers; Cleaning the substrate: piranha solution (3:7 H2O2:H2SO4); alkaline solution (NaOH, KOH) 20 minutes, after that 5 minutes in 1 M hydrochloric acid, finally 20 minutes in pure water; combine piranha solution with alkaline solution;

    4. Concentration of spheres in the solution The nanosphere solution should be diluted with ethanol, methanol, water; The concentration of the solution is calculated with the Micheletto equation:

    5. The Process- 4 Steps

    6. Preparation methods of nanosphere monolayer

    7. Spin Coating Spin speed: 100-2000 rpm; The thickness of the monolayer can be calculated by:

    8. Angle evaporation „Tilting method“ Investigate the monolayer formation by means of varying the angle of the tilt plane from 5° to 15°; Use of a Peltier cell for a good thermal stability; To control the evaporation velocity means to control the temperature;

    9. Dip coating method Controlled dipping of the substrates with a constant velocities smaller than 1mm/s; The coating thickness can be calculated by the Landau-Levich equation:

    10. Gold deposition using ultra high vacuum system

    11. Nanosphere removal Dissolved in Tetrahydrofuran (THF); Soaking in dichlormethane for one minute; Ultrasonic bath in pure water for five minutes;

    12. Ring formation During the evaporation of the liquid micromenisci are formed around the contact area of the colloid particles with the surface; After complete drying rings consisting of material dissolved in the suspension remain;

    13. Hillock formation On the left hand side the particles have been detached and hillocks can be observed; These hillocks are formed as a consequence of the adhesion of the particles; The hillocks never have been found to appear homogeneously over a sample;

    14. Conclusions To achiev a monolayer of polystyrene nanosphere a clean surface is needed; The nanospheres must be uniform to avoid pattern defects; Use 3 application methods: angle evaporation, spin coating, drop coating; Investigate different parameters including spin speed, tilt angle, volume dispersed and temperature, pressure to obtain a highly quality of the monolayer; Investigate possible reactions that occur during growth phase; The sample will be characterized using Atomic Force Microscopy;

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