project ppt

1. Synthesis of CdxZn1-xS thin films by Low-Cost
Chemical Bath Method
Project Report
Submitted to
MANGALORE UNIVERSITY
by
Shrivaths B S
Reg No: 201331403119
Department of Physics
St Philomena College,
Puttur
Under the Guidance of
Dr Ashith V K
Department of Physics
St Philomena College
Puttur

2. Introduction
• It is a device made of using or involving a very thin solid or
liquid film.
• A thin engineered layer of material deposited on a substrate
with a thickness typically measured in nanometers, used in
electronic and optical application.
• A microscopically thin layer of material, ceramic,
semiconductor or plastic base [called substrate].
• A thin film is a layer of material ranging from fractions of a
nanometer (monolayer) to several micrometers in thickness.

3. Introduction
The deposition techniques for thin films may be broadly
classified:
• Physical vapor deposition (PVD)
• Chemical vapor deposition (CVD)
Thin film
deposition
Chemical vapor
deposition
(CVD)
Low pressure
Plasma
enhanced
Atomic layer
Physical vapor
deposition
(PVD)
Themal
evaporation
Sputter

4. Introduction
• Recently, researchers have shown considerable interest in II-VI
compound semiconductor, due to their vast potential for use in
thin film devices.
• The binary compound cadmium sulphide (CdS) and zinc
sulphide (ZnS) semiconductor thin films have wide direct band
gap. Hence, they are highly suitable for optoelectronic device
applications, such as LED’s, photo detectors and solar cells.
• The bandgap of CdxZn1-xS ternary compound can be varied from
2.4 eV to 3.7 eV by varying the composition of cadmium.

5. Chemical Bath Deposition (CBD)
 Films can be grown on either metallic or non metallic
substrates by dipping them in appropriate solutions of metal
salts without the application of any electric field.
 Deposition may occur by homogeneous chemical reactions
usually reduction of metal ions in solution by a reducing
agent.
Factors governing the CBD:
 Bath composition
 The pH
 Deposition time
 Deposition temperature

6. Applications:

7. Experimental Procedure:
• The glass substrates were cleaned with dilute
hydrochloric acid, rinsed with distilled water
and cleaned with acetone.
• The cadmium zinc sulphide thin film were
deposited on glass substrate by chemical bath
method.
• The known amount of zinc chloride ,cadmium
chloride and sodium sulphide were mixed
with water was placed in magnetic stirrer at
room temperature for 3 hours.
• The experiment is repeated for different
atomic composition cadmium, i,e 0.1 of Cd,
0.5 of Cd, 0.9 of Cd respectively

8. RESULTS & DISCUSSIONS
•The films were found to
be polycrystalline. The
patterns show peaks of
the hexagonal phase
corresponding to (100)
and (002) planes
Figure : XRD patterns of CdxZn1-xS thin films
•The positions of the
peaks were found to
change with composition,
indicating a change in
crystal structure
•As the value of x decreases, the hexagonal phase clearly
dominates. ( x – composition i.e., cd )

9. RESULTS & DISCUSSIONS
• The crystallite size of the films was calculated by Scherrer formula.
Table : XRD analysis of CdxZn1-xS films
Figure : XRD analysis of CdxZn1-xS films
Composition Crystallite size
(nm)
Lattice constant (Å) Dislocation
density
x1015 (m-2)
A C
0.1 15.7 3.82 6.26 4.05
0.5 9.2 3.98 6.47 1.18
0.9 16.5 4.14 6.71 3.67

10. RESULTS & DISCUSSIONS
•The absorbance spectra of CdxZn1-xS films with different composition are
shown in figure.
•The absorption edge of the films shifts from UV to the mid-visible region as
the cadmium content in the film increases.
• This behavior indicates the variation of bandgap with composition.
Figure : Absorbance of Cd(0.1)Zn(0.9)S
Figure : Absorbance of Cd(0.5)Zn(0.5)S
Figure : Absorbance of Cd(0.9)Zn(0.1)S
Optical Properties

11. RESULTS & DISCUSSIONS
Optical Properties
•The energy bandgap of the films was determined by Tauc plots
Figure : Bandgap of the Cd(0.1)Zn(0.9)S
Figure : Bandgap of the Cd(0.5)Zn(0.5)S
Figure : Bandgap of Cd(0.9)Zn(0.1)S

12. REFERENCES
• A Goswami,Thin Films fundamentals,New Age
international limited.
• K L Chopra, ‘Thin Film Phenomena’, Mc Graw Hill,New
york
• Erturk, K., Isik, M., Terlemezoglu, M., & Gasanly, N. M.
(2021). Optical and structural characteristics of
electrodeposited Cd 1-xZnxS nanostructured thin films.
Optical Materials,114, 110966
• S.S. Ou, O.M. Stafsudd, B.M. Basol, Journal of Applied
Physics 55, 3769 (1984).
• R. Grecu, E. J. Popovici, M. Lǎdar, L. Pascu, E. Indrea,
Journal of Optoelectronics and Advanced Materials.

13. Conclusion
• Cadmium zinc sulphide (CdxZn1-xS) thin films were prepared by
chemical bath deposition for different composition (x).
• The XRD patterns showed peaks of the hexagonal phase
corresponding to (100) and (002) planes. The crystallite size of
the films varied with composition.
• The lattice constants of the films varied almost linearly with
the composition.
• The energy band gap of the CdxZn1-xSfilms varied non-linearly
with the alloy composition which is highly beneficial for
optoelectronic applications.