Synthesis and characterisation of k doped zno 1

 Thin film technology has been developed primarily
for the need of the integrated circuit industry.
 Thin films cannot exist by itself; it needs substrate
to adhere to.
 Thin film can be treated as two dimensional
specimens because the third dimension namely
the thickness is very small .
 Thin film is created through atomic/molecular
processes

 Chemical Deposition
In CVD process the substrate is exposed to one
or more volatile precursors, which react or
decompose on the substrate surface to produce the
desired deposit.
 Physical Deposition
Physical deposition uses mechanical or
thermodynamic means to produce a thin film of
solid.

 Structural Properties
The most convenient and powerful tool for
the structural study is electron diffraction and
diffraction effect provides information regarding the
nature of these films, their crystal structures, lattice
parameters, grain size etc.
 Electrical Properties
Electrical conductivity of a film is many
orders of magnitude smaller than that of bulk
material and is generally characterized by a
negative temperature coefficient of resistivity

 Optical Properties of Thin Film:
Optical measurements constitute the most
important means of determining the band
structures of semiconductors.
Optical measurements can also be used to study
lattice vibrations.

 Thin Film Drug Delivery
 Optical Coatings
 Thin Film Transistor
 Dye Sensitized Solar Cell
 Applications in Metallurgical Coatings

 Zinc oxide is an inorganic compound with the formula
ZnO. It usually appears as a white powder, nearly
insoluble in water.
Crystal structure of ZnO
 At ambient pressure and temperature, ZnO
crystallizes in the wurtzite structure, hexagonal
lattice.
 ZnO bond also possesses very strong ionic
character, and thus ZnO lies on the borderline of
ionic and covalent compound.

 Rubber manufacture
 Concrete industry
 Medical:
 Cigarette filters
 Food additive
 Pigment
 Coating
 Zinc oxide nanorod sensors
 Piezoelectricity

Objectives
Synthesis of K- doped ZnO thin film by double dip
technique.
 Structural analysis by XRD.
Particle size determination
Determination of cell parameters.
 Measurement of thin film surface resistivity.
Optical analysis by photoluminescence

 The well cleaned substrate was first immersed in
the sodium zincate bath for 10 sec (first dip) and
then dipped in hot water for the same duration
(second dip).
 ZnSO4+4NaOH Na→ 2ZnO2+Na2SO4+2H2O
Na2ZnO2+H2O ZnO+2NaOH→

 In order to improve the gas sensing properties, metal
ions can be doped onto ZnO thin films.
The doped thin films have the following advantages:
 Working temperature can be decreased.
 Response time for sensing can be decreased.
 Sensitivity can be increased.
 The sensitivity for low concentration gas can be
enhanced

 The structural properties of film were studied by X-
ray diffraction analysis using powder diffract meter
 XRD is non- destructive method that reveals
detailed information about the chemical
deposition, crystallographic and microstructure of
all types of natural and manufactured materials.

 The constructive interference can take place when
the Bragg law is satisfied:
2dhkl sinθ = nλ
 θ is the glancing angle of incident x-rays.
 λ is the incident wavelength.
 dhkl is the interplanar distance.
 n is any integer corresponding to spectral order.
For wurtzite structure,
1/d2
hkl = [4/3((h2
+ hk + k2
)/a2
)] + (l/c)2

 Photoluminescence describes the phenomenon of
light emission from any form of matter after the
absorption of photons (electromagnetic radiation).
 In a typical PL experiment, a semiconductor is
excited with a light-source that provides photons
with energy larger than the band gap energy.

 It is a measure of materials surface inherent resistance
to current to flow.
 This electrical resistance is proportional to the samples
length and the resistivity and inversely proportional to
the samples cross sectional area.
 R = ρl/A
where
 R = Resistivity
 A= cross – sectional area
 L = length
 The resistance of ZnO thin film is measured using
Keithley 2100 6 ½ Digital Multimeter which can
measure mega ohm range.

 X – ray powder diffraction may be used to
measure the average crystal size in a powdered
sample.

 FWHM is the full width of the peak at the half of
maximum value of intensity. For full width half
maximum (FWHM), β = x2 – x1 .Debye Sherrer
formula is used to calculate the grain size of the
crystal, grain size D is given by
 D = 0.9λ/ βcosθ
Where:
 β = value of full width in radians
 λ =incident wavelength
 θ = diffraction angle at which peak occurs.

Al 7
Operations: Smooth 0.150 | Background 4.571,0.000 | Import
2)
1)
File: SAIFXR110824B-05(Al7).raw - Step: 0.020 ° - Step time: 31.2 s - WL1: 1.5406 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 35 mA -
Obs. Max: 36.495 ° - FWHM: 0.454 ° - Raw Area: 15.33 Cps x deg. - Net Area: 13.79 Cps x deg.
Obs. Max: 34.694 ° - FWHM: 0.325 ° - Raw Area: 52.36 Cps x deg. - Net Area: 50.45 Cps x deg.
Lin(Counts)
0
1000
2000
3000
4000
5000
2-Theta - Scale
3 10 20 30 40 50 60 70 80
2th=8.106°,d=10.89901
2th=32.002°,d=2.79448
2th=34.685°,d=2.58418
2th=36.497°,d=2.45990
2th=47.841°,d=1.89978
2th=63.231°,d=1.46943

2θ

d values(A0
)
Relative Intensity

31.737
2.81717 56.9

34.379
2.61562 41.5

36.215
2.4784 100

47.484
1.91322 21.2

62.777
1.48414 26.5
1. Standard values of 2θ and d
                     2θ

                d values(A0
) Relative Intensity
32.002

2.79448 45.9
34.685

2.58418 39.2
36.497

2.45990 100
47.841

1.89978 22.2
63.231

1.46943 16.2
2. Observed values of 2θ and d

sample β D(nm)
5% 0.313 26.85
3% 0.4737 17.48
D=kλ/β cosθ
k=0.9
λ=1.542A0

Cell parameter Standard cell
parameter value
(A
o
)
Observed cell
parameter value
(A
o
)
a
b
c
3.25
3.25
5.21
3.23
3.23
5.17

Sample Average particle size
(nm)
Resistance at room temp
(MΩ)
PURE
15.12 10.2
3% 17.48 5
5% 26.85 2

1.Samples of K- doped ZnO thin films were synthesized by double
dip technique.
2.Phase determination of sample was done by XRD technique.
From XRD analysis the sample was found to be phase pure.
3.Average particle size of thin film is calculated. It was found that
as the doping percentage increases particle size also increases.
4.Cell parameters of the film were determined and it is in
agreement with the standard values.
5.Resistance of the samples is measured. As doping concentration
increases resistance was found to be decreased.
6.Optical analysis is done by photoluminescence studies and it was
found that intensity of visible light emission peak was
significantly enhanced with increasing K concentration.
7.By doping particle size of the sample was found to be increased
significantly.

Synthesis and characterisation of k doped zno 1

Synthesis and characterisation of k doped zno 1

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