P R E S E N T E D B Y :

N I S C H I T H B S

THIN FILMS

Define Thin Films!

A thin film is a layer of material ranging from fractions of a nanometer (monolayer) to several micrometers in thickness.

Thin film technology is a "self organizing" structural evolution.

Ex: In ancient times, people already knew how to beat gold into a thin film (<

1 μm thickness) with hammers and knew how use this "gold leaf" for coating all kinds of stuff.

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Purpose of Thin Film development!

o To maintain surface uniformity.

o To reduce the amount (or mass) of light absorbing

material.

o Spray Coating Technology for Superior Functional

Medical Coatings.

o To decrease the weight and bulkiness of the

materials.

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Thin Film Technology

Thin film technology involves deposition of individual molecules or atoms.

Uniform ultra-thin film coatings onto stents, catheters, balloons, endoscopic instruments, pacemakers, heart valves, glucose monitors, sensors, medical textiles, blood collection tubes, surgical implants, orthopedic implants, and diagnostic devices.

Example for industrial thin films produced are:

1. 1.Amorphous Silicon (a-Si)

2. 2.Cadmium Telluride (CdTe)

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Properties to be considered!

FILM THICKNESS : The physical properties of a thin

film are highly dependent on their thickness. Thickness

measurement methods are applied during deposition

("in situ") and methods by which the thickness can be

determined after finishing a coating run ("ex situ").

a) Gravimetric Method b) Optical Method

ROUGHNESS : In Ultrathin Films, it can influence all

film properties such as mechanical, electrical,

magnetical or optical properties. roughness types, the

mechanisms of their origin, roughness measurement

and roughness quantification needs to be taken into

consideration.

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CHEMICAL PROPERTIES:

Conventional methods of chemical analysis as atomic emission, atomic absorption spectral analysis, X-ray fluorescence and mass spectrometry play an important role for the production of the coating materials.

Interaction of photons, electrons, ions or other particles with the coating or surface has to be analyzed.

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Deposition Techniques

DEPOSITION TECHNIQUES

EVAPORATIVE METHODS

GLOW-DISCHARGE TECHNOLOGIES

GAS-PHASE CHEMICAL PROCESSES

LIQUID-PHASE CHEMICAL

FORMATION

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Deposition processes is done to controllably

transfer atoms from a source to a substrate

Chemical Vapour Deposition(CVD)

Gaseous compounds react to form a dense layer on a heated substrate. The most widely deposited wear-resistant coatings are TiC, TiN, chromium carbide and alumina. Deposition temperatures are generally in the range 800-1000C. Thicknesses are limited to about 10mm due to the thermal expansion mismatch stresses which develop on cooling which also restrict the coating of sharp edged components.

Advantages High coating hardness

Good adhesion (if the coating is not too thick)

Good throwing power (i.e.

uniformity of coating)

Disadvantages High temperature process (distortion)

Sharp edge coating is difficult (thermal expansion mismatch stresses)

Limited range of materials can be coated

Environmental concerns about process gases

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Physical Vapour Deposition (PVD)

Advantages Excellent process control

Low deposition temperature

Dense, adherent coatings

Elemental, alloy and compound coatings possible

Disadvantages Vacuum processes with high

capital cost

Limited component size treatable

Relatively low coating rates

Poor throwing power without manipulation of components

Low pressure coating processes in which the coating flux is produced by a physical process. There are two main types:-

1. Evaporation

2. Sputtering

In both cases the source material is a solid (metal or ceramic). A reactive gas may be used in the deposition chamber to deposit compound coatings from an elemental source or maintain the stoichiometry of coatings from compound sources, though thinner layers are used in microelectronics and thicker layers are used for high temperature .

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Ultrasonic Nozzle Technology

Low velocity, soft spray with minimal overspray

saves up to 80% in coating material

Independent control of process parameters

including flow rate, spray velocity, drop size and

deposition

Precise control over a wide range of flow rates

Non-clogging, repeatable performance

Choice of drop size depending on nozzle

frequency (drop sizes range from 18 - 49

microns)

Deagglomeration of particles in suspension due

to ultrasonic vibration

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Thin Film Advantages

o Simple fabricationo Requires low fabrication temp

(300 C)o Manufacturing requires little

materials. -thin cell to crystalline thickness= 1 to 300

o Flexible/ non-breakableo High voltage can be obtainedo No infrastructure needed to

support cellso Cell can double as building

material (roofing tiles, walls, etc)

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Where can we apply it ??

Thin-film Batteries: Thin-film printing technology is being used to apply solid-state lithium polymers to a variety of substrates to create unique batteries for specialized applications. Thin-film batteries can be deposited directly onto chips or chip packages in any shape or size. Flexible batteries can be made by printing onto plastic, thin metal foil, or paper.

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Thin-film solar cells:

also called a thin-film photovoltaic cell (TFPV), is a second generation solar cell that is made by depositing one or more thin layers, or thin film (TF) of photovoltaic material on a substrate, such as glass, plastic or metal.

Thin-film solar cells are commercially used in several technologies, including cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and amorphous and other thin-film silicon

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Blood Collection Tubes

Targeted coating of side walls, layering of

chemistries, polymers, or clotting agents.

Common materials sprayed include Heparin,

Silicone and EDTA.

Nozzle design allows atomizing surface

to reach inner diameter lengths. Fully

automated control of electronics. Custom

multiple nozzle systems for high volume

production. Soft, low velocity spray will not

collect on base of tubes.

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Orthopedic Implants

Thin film coatings of antimicrobial agents or

bone growth enhancing solutions onto rods,

screws, plates, or joint replacements. Low

velocity spray readily adheres to all surfaces.

Ability to adjust coating morphology

characteristics. Tight drop distribution uniformly

coats any shape.

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Microencapsulation

This include targeted drug delivery, slow release pharmaceuticals, and nanoencapsulation.

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http://electrical-engineering-portal.com/solar-energy-expands-escapes-the-power-grid

Thin-Film market demand

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Future of Thin Films18

Natures solution to thin film cells.

Developing molecules out of organic compounds like carbon and hydrogen

Super-thin film about 100 nanometers thick, can be applied as a paint.

Replaces heavy metals currently being used in cells. Creates a biodegradable, almost natural cell.

References

Barna, P. B. (2005). HISTORY OF THIN FILMS. In P. B. Barna, HISTORY OF THIN FILMS (p. 37). Budapest, Hungary: Research Institute for Technical Physics and Materials Science of HAS.

IFP TUWEIN. (2009, September 30). Retrieved from http://static.ifp.tuwien.ac.at: http://static.ifp.tuwien.ac.at/homepages/Personen/duenne_schichten/pdf/t_p_dschapter1.pdf

Jiang, P. D. (2008). Introduction to Thin Film Technology. LOT , 28.

Ohring, M. (2001). Materials Science of Thin Films . Boston: Academic Press.

Seshan, K., & McGuire, G. (2002). HANDBOOK OF THIN-FILM DEPOSITION PROCESSES. Norwich, New York, U.S.A.: NOYES PUBLICATIONS.

(2007, October). Retrieved from en.wikipedia.org: http://en.wikipedia.org/wiki/Thin_film

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