Presantion Project 9

7/28/2019 Presantion Project 9

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APROJECT REPORT ON

SUBMITTED TO CH. CHARAN SINGH UNIVERSITY, MEERUT

FOR THE AWARD OF THE DEGREE OF MASTER OF PHILOSOPHY

IN PHYSICS

SUPERVISOR CANDIDATE DR. BEER PAL SINGH AMIT TOMER

DEPARTMENT OF PHYSICS CH. CHARAN SINGH UNIVERSITY, MEERUT

JUNE-2010


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1.THIN FILM2.THICK FILM3.THIN FILM SCIENCEa. Fabricationb. Characterizationc. Applications

4.APPLICATIONS OF THIN FILM


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PVD we part from asolid materialconverted to vaporthrough heating(evaporation) orenergetic ionbombardment. Thematerial in form ofvapor finally condeseson the substratesurface as a thin film.

CVD we part directlyfrom gases (sometimesvapor originating froma liquid phase) whichreact and give place to anew product that

condenses as a thin filmon the substrate.


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ZnO is an important multifunctional material whichhas received great attention during the last few yearsdue to their unique applications in microelectronic andoptoelectronic devices, and for self-assembled growthof three-dimensional nanoscale systems. Zinc oxidehaving a direct band gap of 3.37 eV and an excitonbinding energy (60 eV) higher than those of ZnS (20eV)and GaN (21eV), is of interest for various high techapplications,such as optical devices, solar cells,piezoelectric devices ,varistors surface acoustic wave(SAW) devices, and gas sensors .(a) its simplicity and low cost, (b) its capability toachieve large area coatings, (c) its low


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Group II-VIUsually p-type, except ZnTe which is n-type

II-VI semiconductorsCadmium selenide (CdSe) (1.74 eV, direct band gap)Cadmium sulfide (CdS) (2.42 eV, direct band gap, common for quantum dots)

Cadmium telluride (CdTe) (1.49 eV)Zinc oxide (ZnO) (3.37 eV, direct band gap)Zinc selenide (ZnSe) (2.7 eV)Zinc sulfide (ZnS) (3.68 eV)Zinc telluride (ZnTe) (2.25 eV)

II-VI ternary alloy semiconductorsCadmium zinc telluride (CdZnTe, CZT) (1.4-2.2 eV, direct band gap)Mercury cadmium telluride (HgCdTe)Mercury zinc telluride (HgZnTe)Mercury zinc selenide (HgZnSe)


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RUBBER ACTIVATION ACCELERATION BIOCHEMICAL

ACTIVITY DIELECTRICSTRENGTH HEAT STABILIZATION LATEX GELATION LIGHTSTABILIZATIONPIGMENTATION REINFORCEMENT

RUBBER - METALBONDING TACK RETPLASTICS CERAMICS

PHARMACEUTICALINDUSTRY COSMETICS ADHESIVES,MASTICS, SEALANTS PHOTOCOPYING LUBRICANTS PAINTS


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1.Physical processes2.Chemical processes

3.Physical-chemical process(Glow-discharge process)


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1. Thermal evaporation (Physicalvapor Deposition)

2. Resistive Heating Evaporation3. Electron Beam Evaporation4. Laser Evaporation5. Flash Evaporation6. Arc Evaporation7. The Physics and Chemistry of

Evaporation


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When a volatile compound to be deposited on the substrate isvaporized and vapor is thermally decomposed with othergases, the vapor phase react chemically near or on a substratesurface to form a solid product which deposit atomistically(atom by atom) on the substrate. This is called CVD

1. Atmospheric pressure CVD (APCVD)2.Low pressure CVD (LPCVD)3.Metal Organic CVD (MOCVD)4.Photo - enhanced CVD (PHCVD)5.Laser induced CVD (PCVD) and Electron enhanced CVD

.


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Rough vacuum 760 to 0.1 torr

Medium vacuum 0.1 to 10-4

torrHigh vacuum 10-4 to 10 -8 torr

Ultra High vacuum 10-8 torr


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Pump Type Pumping Capacity Preferred Backing

Pump

Diffusion Pump Unlimited Rotary Oil

Hook and Claws

Turbo molecular

pump

Unlimited Rotary Oil,

Hook and Claws

Getter-ion pump Limited Sorption

Getter Pump Limited Sorption

Cryopump Limited Any


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Screen printing is a printing technique that uses awoven mesh to support an ink-blocking stencil.The attached stencil forms open areas of mesh thattransfer ink as a sharp-edged image onto asubstrate. A roller or squeegee is moved across thescreen stencil, forcing or pumping ink past thethreads of the woven mesh in the open areas.A pattern is photo graphically defined on astainless steel screen by means of an emulsionlayer. A paste of the material to be screen printed ispressed through the screen by means of a squeegee.


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Advantage of screen printing is that large quantitiescan be produced rapidly with new automatic presses,up to 1800 shirts in 1 hour. The current speed loadingrecord is 1805 shirts printed in one hour, documentedon 18 February 2005. Maddie Sikorski of the NewBuffalo Shirt Factory in Clarence, New York (USA) setthis record at the Image Wear Expo in Orlando,Florida, USA, using a 12-colour M&R Formula Pressand an M&R Passport Automatic Textile Unloader.The world speed record represents a speed that is overfour times the typical average speed for manualloading of shirts for automated screen printing.


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Plastisol Water-Based inksPVC/ Phalate Free

Discharge inksGlitter/ShimmerMetallicExpanding ink (puff)

GlossNylobondMirrored silver


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1.Screen printing is arguably the most versatile ofall printing processes2.It can be used to print on a wide variety ofsubstrates, including paper, paperboard, plastics,glass, metals, fabrics, and many other materials.3.greater thickness of the ink can be applied to thesubstrate than is possible with other printingtechniques

4.The advantage of screen printing over other printprocesses is that the press can print on substratesof any shape, thickness and size.


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It is very important to thoroughly characterizethe films, for making them useful in device

fabrication. There are following techniques forthe characterization of the films1. Optical properties2. Structural properties3. Electrical properties


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1.Optical AbsorptionIn the absorption process a photon of known energy excites anelectron from a lower to a higher energy state. In other manner wecan say that absorption is also resulted from interaction betweenatoms and electromagnetic radiations.

2.Optical transmission overall transmission is given by,

T = (1-R)2 exp(-t) = (1-R)2 exp(-2(-t)

if product t is large then we can write, T = (1-R)2 exp(- t).

Determination of optical constants: the optical behaviour of amaterial is generally used to determine the optical constants

n (refractive index)


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X-ray Diffraction (XRD) The diffractionof x-rays by the crystal lattice is known as x-raydiffraction .The phenomenon of x-ray diffractioncan be considered as a reflection of x-rays from thecrystallographic plane of the material and isgoverned by Bragg s equation

nd sin2


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The scanning electron microscope (SEM ) is atype of electron microscope that images the

sample surface by scanning it with a high-energybeam of electrons in a raster scan pattern. Theelectrons interact with the atoms that make upthe sample producing signals that containinformation about the sample's surfacetopography, composition and other propertiessuch as electrical conductivity


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A Commercially available ZnO powder with 99.99%purity was used as the starting material. Slurryconsisting of ZnO powder, 10% weight of ZnCl2 andan appropriate amount of ethylene glycol werethoroughly mixed. ZnCl2 was used as an adhesiveand ethylene glycol as a binder. The paste thusprepared was screen printed on ultra-clean glasssubstrates. It was then cleaned by embry powder,acetone and finally washed with distilled water. Thesamples thus prepared were dried at 120C for 4hours in the open air.


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Optical properties:- Reflection spectra of sintered ZnO films istaken at room temperature with the help of a HitachiSpectrophotometer model U-3400.In this model theprism/grating double monochromatic system is used, the lensesused in conventional monochromator are replaced with mirrors.So, the image deviation due to chromatic aberration iseliminated. Its wavelength range is 187- 2600nm.The leadsulphide detector (PbS) is used for the detection of infrared rays.The visible wavelength light source is long life WL lamp. Theoptical band gaps of these films are determined with the help of

reflection spectraAccording to Tauc relation, the absorption coefficient for directband gap material is given by h = A (h - Eg)n , Where h isphoton energy, A is constant, Eg is the band gap, and n is equal for direct band gap material


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GRAPH BETWEEN LAMDA(nm) Vs R%

0

0.05

0.1

0.15

0.2

350 450LAMDA (nm)

R %


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GRAPH BETWEEN hv (eV) Vs (h)2

0

20

40

60

80

100

3 3.2 3.4 3.6

hv(eV)

(h)2


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30 40 50 60 701000

2000

3000

4000

5000

6000

(201)(200)

(112)(220)(110)

(102)

(101)

(002)

(100)

C o u n

t s

2Theta


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30 40 50 60 70

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

201

112

200

220110102

101

002

100

C o u n t s

2Theta


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Surface morphology of ZnO films deposited onglass substrate was examined by scanning electron

microscope(SEM).The scanning electron micrographof deposited ZnO film are shown in fig. SEManalysis suggests that the surface of ZnO is roughand grains are distributed uniformly. The Scanningelectron micrograph of sintered deposited ZnO filmat sintered 425C 450C respectively.


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I have deposited zinc oxide thin films by screen printingusing sintering technology. and I have calculated the

energy band Gap of prepared ZnO thin films wascalculated with the help of Reflection spectra which iscomes out by the Tauc relation. The Energy band gap ofZnO samples is 3.22 eV and I have done the XRD of ZnOthin films. The nature of the Band gap of ZnO comes outby Reflection spectra .almost all the II-VI compounds aredirect band gap semi conductors according to Taucrelation


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In Future we will deposit the thin film of ZnOby Vacuum Deposition technique UsingVacuum coating unit. In this technique we will

use Quartz substrate in place of Glasssubstrate. After that we will calculate theOptical Constant, Electric property, Surfacemorphology structure, nature of Band gap and

particle size etc. in ZnO thin film .


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Presantion Project 9

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