This document describes a project on the formation of PbS thin films using the chemical bath deposition technique. The aims are to deposit PbS thin films using CBD, study the effect of different precursor solutions, and characterize the films using XRD. CBD is described as a low-cost deposition method using controlled chemical reactions. Procedures for depositing PbS films using lead acetate and lead nitrate precursors are provided. XRD results show the films are PbS cubic crystals with grain sizes of 41.9nm and 45.44nm for lead nitrate and acetate, respectively. Conductivity tests show the films are p-type. The effect of varying lead concentration is also studied.
This document discusses photoluminescence, which is the emission of light from a material upon exposure to light or other electromagnetic radiation. It begins by classifying luminescence and describing photoluminescence as a specific type involving absorption of photons and emission of photons as electrons return to lower energy states. The key processes of photoluminescence are excitation, relaxation, and emission. It then distinguishes between two types of photoluminescence - fluorescence, which is a rapid emission, and phosphorescence, which involves a spin-forbidden state and longer-lasting emission. The document concludes by outlining applications of photoluminescence spectroscopy for materials characterization and explaining the differences between photoluminescence and
CdxZn1-xS thin films were synthesized via chemical bath deposition for various cadmium compositions. XRD analysis showed the films were polycrystalline with hexagonal structure, and crystallite size varied with composition from 9.2 to 16.5 nm. Absorption spectra indicated the bandgap shifted from UV to visible with increasing cadmium content. Tauc plot analysis demonstrated the bandgap could be varied non-linearly from 2.4 to 3.7 eV by changing the cadmium composition, making CdxZn1-xS suitable for optoelectronic applications.
If you have any questions, contact me. I would be happy to help.
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In this presentation,
The author gives the working principle of the PVD and Sputtering methods. But you can also find an information about the thin film and plasma phase of a matter.
Also this is related with Magnetron Sputtering method.
This document discusses semiconductor nanomaterials and their applications in energy and the environment. It begins by defining semiconductors and discussing how their properties change at the nanoscale due to quantum effects. Common semiconductor materials include silicon, which is used in most electronics, as well as gallium arsenide and others. The document then covers topics such as doping to create n-type and p-type semiconductors, direct and indirect bandgaps, recombination processes, and quantum structures including quantum wells, wires and dots. Nanocrystals were first discovered in the 1980s and exhibit size-dependent optical properties due to quantum confinement effects.
The document discusses chemical vapor deposition (CVD) and was presented by a team of 4 students. CVD involves depositing a solid film on a substrate through chemical reactions of vapor phase precursors. The major sections describe the CVD apparatus, process, types including atmospheric pressure CVD, low pressure CVD and plasma enhanced CVD. The applications of CVD include coatings, semiconductor devices, optical fibers and composites. Advantages are high growth rates, versatility in deposited materials and purity. Disadvantages include high temperatures and complex toxic processes.
It's simple to understand the synthesis. Hydrothermal method is a chemical reaction in water in a sealed pressure vessel, which is in fact a type of reaction at both high temperature and pressure.
Focused ion beam (FIB) systems use a finely focused beam of gallium ions to image and mill samples at the micrometer and nanometer scale. FIB works similarly to scanning electron microscopy but uses ions instead of electrons. Gallium liquid metal ion sources are most common and produce beams with nanometer spot sizes. FIB allows for high resolution imaging as well as precise site-specific milling or deposition through ion beam induced deposition of materials like tungsten.
A vibrating sample magnetometer (VSM) measures the magnetic properties of materials by vibrating a sample in a uniform magnetic field and measuring the magnetic moment. It works by vibrating a sample in between sensor coils within an electromagnet, which produces a magnetic field. The sensor coils detect the sample's magnetization and transmit the data to an amplifier, lock-in amplifier, and computer interface. VSMs can characterize the magnetic properties of powders, bulk materials, crystals, and single crystals. They are used to measure magnetic fields and determine the magnetic properties of minerals and ores.
Thin film fabrication using thermal evaporationUdhayasuriyan V
Thermal evaporation is a physical vapor deposition technique where a material is heated in a vacuum until its surface atoms evaporate and are deposited as a thin film on a substrate. The document discusses the principles and working of thermal evaporation, including how the source material is resistively heated to evaporation, how substrates are cleaned, and the advantages of producing films in a high vacuum like reduced impurities. Thermal evaporation can deposit pure elements or compounds and is used to fabricate thin films for applications like semiconductors, solar cells, and optics.
This document describes the arc discharge method for synthesizing nanomaterials. It discusses how an arc discharge works by thermionic emission to vaporize electrode materials and form a plasma. The document provides details on the experimental setup, conditions for producing single-walled carbon nanotubes, and applications of the arc discharge method such as synthesizing carbon nanotubes, metal nanoparticles, and nanowires.
This presentation is about phtoocatalytic process and nanomaterials as photocatalyst. This is useful in the treatment of wastewater and environmental remediation applications.
X-ray photoelectron spectroscopy (XPS) or Electron spectroscopy for chemical analysis (ESCA) is used to investigate the chemistry at the surface of the samples. The basic mechanism behind an XPS instrument is that the photons of a specific energy are used to excite the electronic states of atoms at and just below the surface of the sample.
There are several areas suited to measurement by XPS:
1. Elemental composition
2. Empirical formula determination
3. Chemical state
4. Electronic state
5. Binding energy
6. Layer thickness in the upper portion of surfaces
XPS has many advantages, such as it is is good for identifying all but two elements, identifying the chemical state on surfaces, and is good with quantitative analysis. XPS is capable of detecting the difference in the chemical state between samples. XPS is also able to differentiate between oxidations states of molecules.
XPS has also some limitations, for instance, samples for XPS must be compatible with the ultra high vacuum environment. XPS is limited to measurements of elements having atomic numbers of 3 or greater, making it unable to detect hydrogen or helium. XPS spectra also take a long time to obtain. The use of a monochromator can also reduce the time per experiment.
Basic operating principle and instrumentation of photo-luminescence technique. Brief description about interpretation of a photo-luminescence spectrum. Applications, advantages and disadvantages of photo-luminescence.
The document discusses the scanning tunneling microscope (STM), which uses quantum tunneling to produce atomic-scale images of surfaces. Key points:
- The STM was invented in 1981 and won the Nobel Prize in Physics in 1986. It allows visualization of individual atoms and manipulation of single atoms.
- The STM works by scanning a sharp conductive tip very close to a sample surface. A bias voltage causes electrons to tunnel between tip and surface, producing a current that varies with atomic topography.
- STM can image in various environments, with resolutions down to 0.1 nm laterally and 0.01 nm vertically. It has found many uses including atomic manipulation and etching.
This document discusses physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques for thin film deposition. It covers common PVD methods like thermal evaporation, sputtering, and molecular beam epitaxy. It also discusses CVD reaction mechanisms, step coverage, and overview. Key aspects include comparing evaporation and sputtering, deriving equations for mean free path and deposition rate, and factors affecting step coverage in CVD like temperature and pressure.
The document provides an overview of X-ray Photoelectron Spectroscopy (XPS) as a surface analysis technique. It describes how XPS works based on the photoelectric effect, and how it can be used to identify elements, chemical states, and compounds present on material surfaces. The key components of an XPS instrument are also outlined.
Xps (x ray photoelectron spectroscopy)Zaahir Salam
The document provides an overview of X-ray photoelectron spectroscopy (XPS) technology. XPS works by irradiating a sample surface with x-rays and measuring the kinetic energy and number of electrons that escape from the top 1-10 nm of the material. This allows one to determine the sample's elemental composition and chemical/electronic states. Key aspects discussed include the use of ultra-high vacuum conditions to prevent surface contamination and allow for accurate analysis. Characteristic XPS spectra are produced that contain peaks corresponding to different elemental binding energies.
Characterisation of NanostructuredLead Selenide (PbSe) Thin Films for Solar D...IOSR Journals
The document summarizes research characterizing nanostructured lead selenide (PbSe) thin films deposited using chemical bath deposition for potential solar device applications. PbSe thin films were deposited on glass substrates at varying pH levels of the deposition bath. Characterization of the structural, optical and electrical properties of the films showed that film thickness and properties like band gap energy and conductivity could be controlled by varying the deposition parameters like pH. Higher pH levels resulted in films with lower conductivity and band gap, indicating the properties of PbSe could be tuned for different functions. The nanostructured PbSe thin films showed potential for use in solar energy devices based on their optical absorption properties.
Synthesis and characterisation of k doped zno 1Jeslin Mattam
Thin film technology has been developed for integrated circuits. Thin films are two-dimensional due to their small thickness and need a substrate. They are created through atomic/molecular processes like chemical vapor deposition or physical deposition. Structural properties are analyzed using electron diffraction and electrical properties depend on temperature. Optical measurements determine band structure and lattice vibrations. Applications include drug delivery, optical coatings, transistors, solar cells, and metallurgical coatings. Zinc oxide thin films were synthesized with potassium doping and analyzed. X-ray diffraction showed the films were phase pure wurtzite structure. Resistance decreased and particle size increased with higher doping concentration.
This document summarizes a lecture on thin film deposition techniques given by Dr. Toru Hara. It begins with definitions of thin films and their applications in electronic devices, optical coatings, optoelectronic devices, and quantum devices. It then provides brief introductions to specific applications like transistors, oxygen sensors, and LEDs. The main deposition techniques are also summarized, including chemical methods like plating, CSD, CVD, and ALD, as well as physical methods like thermal evaporation, sputtering, PLD, and MBE. Examples of equipment schematics are provided for many of the techniques.
The document provides an overview of a lecture on thin film deposition techniques given by Dr. Toru Hara. It discusses four main applications of thin films: 1) electronic semiconductor devices using band engineering, 2) optical coatings using refractive index engineering, 3) optoelectronic devices using both band and refractive index engineering, and 4) quantum devices using quantum dynamics design. It also describes common thin film deposition methods including chemical solution deposition, chemical vapor deposition, plating, and physical vapor deposition techniques and gives examples of their use in applications such as transistors, optical coatings, LEDs, and superlattices.
The document describes a study on the effect of annealing on the optical properties of cadmium sulfide (CdS) thin films deposited using chemical bath deposition. CdS thin films were deposited on glass substrates at optimized deposition parameters. The as-deposited films and films annealed at temperatures from 100-400°C were characterized using UV-visible spectroscopy. Annealing was found to cause a blue shift in the absorption edge and increase the optical band gap and transmittance of the films. The highest band gap of 3.8 eV and transmittance of 64% were observed for the film annealed at 400°C. Annealing improves the optical properties of CdS thin films by modifying the structural properties of the
This document discusses nanoscience and nanotechnology, with a focus on ferrites. It defines nanoscience and describes nanomaterials, classifying them based on dimensionality. Ferrites are introduced as magnetic materials made of iron and other transition metals. Common ferrite types include spinel, garnet, and hexa ferrites. Synthesis techniques for ferrite nanoparticles are covered, including high energy ball milling, sol-gel, hydrothermal, and co-precipitation methods. Characterization techniques like XRD and FTIR are also summarized.
Introduction to nanoparticles and bionanomaterialsShreyaBhatt23
what is a nanoparticle, why small is good,nanoscale effect, how to make nanostructures,top down and bottom up approachs,
methods of making nanomaterials,chemical methods od making nanomaterial,bionanomaterials,
Analysis Of Carbon Nanotubes And Quantum Dots In A Photovoltaic Device Slide ...M. Faisal Halim
Francis' presentation to Louis Stokes Association for Minority Participation. Since I co-authored this work I think I have the right to a copy. I was the graduate student Francis was working with.
This document summarizes a seminar presentation about irradiation effects in high melting oxides and the synthesis of new luminescent composite materials. The presentation covered self-introduction of the speaker, introduction to the topic, purpose of the study which was to investigate irradiation effects in oxides like MgAl2O4 and α-Al2O3 as well as synthesize luminescent composites. Experimental methods used included irradiation of samples using neutrons and electrons followed by measurement techniques like photoluminescence spectroscopy. Results showed irradiation induced defects in oxides and conversion of Sm3+ to Sm2+ in Na2SO4 under irradiation. In conclusion, irradiation was found to modify optical and structural properties of materials.
Characterization Studies of CdS Nanocrystalline Film Deposited on Teflon Subs...IJLT EMAS
In this article, different substrates for deposition of
CdS material have been discussed. Till date glass, mica, quartz,
ceramic, etc. are commonly employed substrates in thin film
growth. In the present work, CdS is deposited on Teflon
substrate by chemical bath deposition (CBD) method. Also the
films were deposited on different substrates like glass, copper
and zinc and compared with those prepared on Teflon substrate.
The films prepared on Teflon substrate were uniform, stable and
also showed good radiating property. These films were further
characterized by UV-VIS absorption spectral studies, SEM and
EDS studies.
This document describes a passively Q-switched Nd:YAG ceramic laser using a single wall carbon nanotube saturable absorber. The laser generated pulses with a maximum duration of 1.2 ms, repetition rate varying from 14 to 95 kHz, and maximum pulse energy of 4.5 mJ at a repetition rate of 31.8 kHz. The laser achieved a maximum output power of 376 mW and optical-to-optical conversion efficiency of 4.3% at a pump power of 8.68 W. Characterization of the Nd:YAG ceramic gain medium showed scattering and absorption losses similar to a crystal, with the ceramic laser demonstrating output power only 6.3% lower than an equivalent
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Optimization of optical properties of annealed cadmium selenide (cdse) thin f...Alexander Decker
1) Cadmium selenide thin films were deposited on glass substrates at room temperature (25°C) and a higher temperature (74°C) using a chemical bath deposition technique with sodium selenosulphite as the selenium source.
2) The films were annealed at different temperatures and their optical properties like transmittance, reflectance, and band gap were analyzed using spectroscopy.
3) The results showed that the films deposited at room temperature had higher band gaps than those deposited at 74°C. Transmittance increased with lower annealing temperatures while absorbance and reflectance increased with higher annealing temperatures.
Synthesis and Characterization of ZnS Nanostructured Thin Films using Chemica...IRJET Journal
ZnS nanostructured thin films were deposited on glass substrates using a chemical spray pyrolysis technique. The films were characterized through various methods. X-ray diffraction analysis revealed the films had a cubic crystal structure with an average crystallite size of 3.84 nm. Scanning electron microscopy showed the film's surface was composed of uniform sphere-like particles. Energy dispersive x-ray spectroscopy confirmed the film's composition of Zn, S, and small amounts of O. Optical analysis found the film had a band gap of 3.5 eV and photoluminescence emission in the 350-530 nm range, indicating suitability for optoelectronic applications.
This to demonstrate the laser ablation of hard materials to form a thin film for optical sensors. The work was done at DIllard University , New Orleans LA by Professor Abdalla Darwish. any comment e-mail adarwish@bellsouth.net.
Influence of Manganese doping on Structural, optical and ethanol sensing of S...IRJET Journal
This document summarizes research on the influence of manganese doping on the structural, optical, and ethanol sensing properties of copper oxide thin films synthesized using successive ion layer adsorption and reaction technique. Key findings include:
- X-ray diffraction analysis showed manganese doping reduced grain size up to 5% doping due to increased microstrain, beyond which grain size increased.
- Optical studies found the band gap increased with doping up to 5% due to the Burstein-Moss effect, then decreased with further doping likely due to excess manganese in interstitial sites.
- The 5% doped film exhibited the highest sensitivity of 87% for detecting 1500 ppm ethanol at
This document summarizes a final year project on depositing CdSe nanoparticles multilayers using chemical bath deposition. It introduces CdSe and its properties, the chemical bath deposition technique, and how it was used to deposit different sized CdSe nanoparticles by varying the concentration of the complexing agent NTA. Characterization of the deposited nanoparticles found smaller sizes were produced with higher NTA concentrations. Attempts to deposit two CdSe layers of different sizes on a substrate did not improve solar cell efficiency compared to a single layer. Further work is recommended to address Ostwald ripening in the deposition solution.
Spray pyrolysis is a technique used to prepare oxide films, ceramic coatings, and nanoparticles. It involves atomizing a precursor solution containing metal salts, transporting the sprayed droplets to a heated substrate, and pyrolyzing the salts to form the desired material. Some key advantages of this technique are its simplicity, low cost, versatility for multi-layer deposition, and ability to produce materials for a variety of applications including solar cells, gas sensors, and solid oxide fuel cells. The morphology and properties of films produced can be controlled through parameters like substrate temperature, precursor solution composition, and flow rate.
Transparent and Conducting TiO2 : Nb Thin Films Prepared by Spray Pyrolysis T...arj_online
1) The document describes a study on preparing transparent and conducting niobium-doped titanium dioxide (TNO) thin films using the spray pyrolysis technique.
2) Undoped and niobium-doped TiO2 films were deposited on glass substrates at 500°C from precursor solutions. Increasing the Nb concentration was found to decrease the film resistivity.
3) The minimum resistivity of 3.36×10-3 Ω cm was obtained for a 2% Nb-doped TiO2 film after annealing in hydrogen at 500°C. X-ray diffraction analysis showed the films had a polycrystalline anatase structure without impurities.
Effect of zinc on structural and some optical properties of cd s thin filmsAlexander Decker
This document summarizes research on the structural and optical properties of cadmium sulfide (CdS) thin films doped with varying concentrations of zinc (Zn). X-ray diffraction analysis showed that all films had a hexagonal structure and were polycrystalline. Grain size decreased with increasing Zn concentration, while surface roughness decreased based on atomic force microscopy. Optical analysis found that transmittance increased with Zn concentration, as did the optical band gap. Increasing the Zn dopant concentration improved some structural and optical properties of the CdS thin films.
Lecture Notes Unit4 Chapter13 users , roles and privilegesMurugan146644
Description:
Welcome to the comprehensive guide on Relational Database Management System (RDBMS) concepts, tailored for final year B.Sc. Computer Science students affiliated with Alagappa University. This document covers fundamental principles and advanced topics in RDBMS, offering a structured approach to understanding databases in the context of modern computing. PDF content is prepared from the text book Learn Oracle 8I by JOSE A RAMALHO.
Key Topics Covered:
Main Topic : USERS, Roles and Privileges
In Oracle databases, users are individuals or applications that interact with the database. Each user is assigned specific roles, which are collections of privileges that define their access levels and capabilities. Privileges are permissions granted to users or roles, allowing actions like creating tables, executing procedures, or querying data. Properly managing users, roles, and privileges is essential for maintaining security and ensuring that users have appropriate access to database resources, thus supporting effective data management and integrity within the Oracle environment.
Sub-Topic :
Definition of User, User Creation Commands, Grant Command, Deleting a user, Privileges, System privileges and object privileges, Grant Object Privileges, Viewing a users, Revoke Object Privileges, Creation of Role, Granting privileges and roles to role, View the roles of a user , Deleting a role
Target Audience:
Final year B.Sc. Computer Science students at Alagappa University seeking a solid foundation in RDBMS principles for academic and practical applications.
URL for previous slides
chapter 8,9 and 10 : https://www.slideshare.net/slideshow/lecture_notes_unit4_chapter_8_9_10_rdbms-for-the-students-affiliated-by-alagappa-university/270123800
Chapter 11 Sequence: https://www.slideshare.net/slideshow/sequnces-lecture_notes_unit4_chapter11_sequence/270134792
Chapter 12 View : https://www.slideshare.net/slideshow/rdbms-lecture-notes-unit4-chapter12-view/270199683
About the Author:
Dr. S. Murugan is Associate Professor at Alagappa Government Arts College, Karaikudi. With 23 years of teaching experience in the field of Computer Science, Dr. S. Murugan has a passion for simplifying complex concepts in database management.
Disclaimer:
This document is intended for educational purposes only. The content presented here reflects the author’s understanding in the field of RDBMS as of 2024.
This presentation was provided by Shaina Lange of Kidney News, and Dianndra Roberts of the Royal College of Psychiatrists (RCPsych), for the fifth session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session Five: 'DEIA in Peer Review,' was held July 11, 2024.
How To Sell Hamster Kombat Coin In Pre-marketSikandar Ali
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Search for cryptocurrency boards, social media groups (like Discord or Telegram), or special pre-market buying and selling structures wherein new crypto cash are traded. You can search for forums or companies that focus on new or lesser-acknowledged coins.
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How To Sell Hamster Kombat Coin In Pre Market
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View Inheritance in Odoo 17 - Odoo 17 SlidesCeline George
Odoo is a customizable ERP software. In odoo we can do different customizations on functionalities or appearance. There are different view types in odoo like form, tree, kanban and search. It is also possible to change an existing view in odoo; it is called view inheritance. This slide will show how to inherit an existing view in Odoo 17.
APM event held on 9 July in Bristol.
Speaker: Roy Millard
The SWWE Regional Network were very pleased to welcome back to Bristol Roy Millard, of APM’s Assurance Interest Group on 9 July 2024, to talk about project reviews and hopefully answer all your questions.
Roy outlined his extensive career and his experience in setting up the APM’s Assurance Specific Interest Group, as they were known then.
Using Mentimeter, he asked a number of questions of the audience about their experience of project reviews and what they wanted to know.
Roy discussed what a project review was and examined a number of definitions, including APM’s Bok: “Project reviews take place throughout the project life cycle to check the likely or actual achievement of the objectives specified in the project management plan”
Why do we do project reviews? Different stakeholders will have different views about this, but usually it is about providing confidence that the project will deliver the expected outputs and benefits, that it is under control.
There are many types of project reviews, including peer reviews, internal audit, National Audit Office, IPA, etc.
Roy discussed the principles behind the Three Lines of Defence Model:, First line looks at management controls, policies, procedures, Second line at compliance, such as Gate reviews, QA, to check that controls are being followed, and third Line is independent external reviews for the organisations Board, such as Internal Audit or NAO audit.
Factors which affect project reviews include the scope, level of independence, customer of the review, team composition and time.
Project Audits are a special type of project review. They are generally more independent, formal with clear processes and audit trails, with a greater emphasis on compliance. Project reviews are generally more flexible and informal, but should be evidence based and have some level of independence.
Roy looked at 2 examples of where reviews went wrong, London Underground Sub-Surface Upgrade signalling contract, and London’s Garden Bridge. The former had poor 3 lines of defence, no internal audit and weak procurement skills, the latter was a Boris Johnson vanity project with no proper governance due to Johnson’s pressure and interference.
Roy discussed the principles of assurance reviews from APM’s Guide to Integrated Assurance (Free to Members), which include: independence, accountability, risk based, and impact, etc
Human factors are important in project reviews. The skills and knowledge of the review team, building trust with the project team to avoid defensiveness, body language, and team dynamics, which can only be assessed face to face, active listening, flexibility and objectively.
Click here for further content: https://www.apm.org.uk/news/a-beginner-s-guide-to-project-reviews-everything-you-wanted-to-know-but-were-too-afraid-to-ask/
BÀI TẬP BỔ TRỢ 4 KỸ NĂNG TIẾNG ANH LỚP 12 - GLOBAL SUCCESS - FORM MỚI 2025 - ...
Rani
2. Under the Guidance of
Dr. ANGEL SUSAN
CHERIAN
DEPARTMENT OF
PHYSICS
MAR THOMA
COLLEGE
THIRUVALLA,KERALA
2013-2015
A PROJECTON
THIHFILM FORMATIONUSINGCHEMICALBATH DEPOSITION
Presented by
RANI RAJAN
DEPARTMENT OF PHYSICS
MAR THOMA COLLEGE
THIRUVALLA,KERALA
3. AIM
To deposit PbS thin film using chemical
bath deposition (CBD) technique.
To study the effect of different precursor
solution in the formation of thin film.
To study the structural characterization
of the film by using X-ray diffraction
(XRD) method
To study the effect on conductivity of the
film with the variation on lead content
4. THIN FILM
• Any solid or liquid object with one of its dimensions very
much less than that of the other two may be called a “thin
film”.
• A thin film is a layer of material ranging from fractions of a
nanometer (monolayer) to several micrometers in thickness.
• Electronic semiconductor devices and optical coatings are the
main applications benefiting from thin-film construction.
• The most commonly observed phenomenon associated with
thin film is the fascinating colours on it. e g. a thin layer of oil
floating on the surface of water.
5. •Thin films can be classified into three types based on
the range of their thickness
Ultra thin(50-100 A0 )
Thin(or very thin)(100-1000 A0 )
Comparatively thicker(greater than 1000 A0 )
6. APPLICATIONS OF THIN FILM
• A familiar application of thin films is the
household mirror, which typically has a thin
metal coating on the back of a sheet of glass to
form a reflective interface.
•Work is being done with thin films for use as
computer memory.
•It is also being applied to pharmaceuticals, via
thin-film drug delivery.
•Thin films are used to produce thin-film
batteries.
•Thin films are also used in dye-sensitized solar
cells.
7. DEPOSITION
The act of applying a thin film to a surface is
thin-film deposition or any technique for
depositing a thin film of material on to a
substrate or on to previously deposited layers
8. DEPOSITION TECHNIQUES
Deposition techniques can be broadly classified into
two:
1) Physical :uses mechanical, electromechanical or
thermodynamic means to produce a thin film of solid.
2) Chemical: Here, a fluid precursor undergoes a
chemical change on a solid surface, leaving a solid
layer
10. • Plating
• Chemical bath deposition
• Spin coating or spin casting
• Chemical vapour deposition
• Plasma enhanced CVD
• Atomic layer deposition
11. The Chemical bath deposition (CBD) method is one of
the cheapest methods to deposit thin films and nano
materials, as it does not depend on expensive
equipment and is a scalable technique that can be
employed for large area batch processing or continuous
deposition.
The chemical bath deposition (CBD) method uses a
controlled chemical reaction to effect the deposition of
a thin film by precipitation.
Substrates are immersed in a chemical bath containing
precursor solution
12. Advantages
It requires only solution containers and substrate
mounting devices.
Among various deposition techniques, chemical bath
deposition yields stable, adherent, uniform and hard
films.
It is one of the suitable methods for preparing highly
efficient thin films in a simple manner.
Disadvantages
Wastage of solution after every deposition.
Proper substrate cleaning is a very important factor in
obtaining good adherent films
14. Molecular formula = PbS
Molar mass = 239.30 g/mol
Density = 7.60 g/cm3
Melting point = 1,118 °C (2,044 °F; 1,391 K)
Boiling point = 1,281 °C (2,338 °F; 1,554 K)
Band gap energy = 0.4eV
DESCRIPTION OF PbS
15. APPLICATIONS OF PBS
PbS was once used as a black pigment, but
current applications exploit its semiconductor
properties .
As an infrared detector due to its narrow
band gap
17. • The reactive substances used to obtain the
PbS thin film were lead acetate/lead nitrate
(Pb(CH3COO)2)/ (Pb(NO3)2), sodium hydroxide
(NaOH) and thiourea(SC(NH2)2) and H2O for
different concentration at constant room
temperature.
18. PREPARATION OF PbS USING LEAD NITRATE
(PRECURSOR SOLUTION)
The first step was to prepare 1M solution of Thiourea
(SC(NH2)2),Lead nitrate (Pb(NO3)2 ), and Sodium hydroxide
(NaOH),.
The second step is to prepare chemical bath using this
solutions
The third step is to immerse the substrate on the precursor
solution
19. • First the complexing agent NaOH was added to lead
nitrate and after some time Thiourea was added.
• A white precipitated solution was formed which
turned into a blackish colour after some time which
indicates the presence of PbS.
• NaOH fixes the alkalinity of lead nitrate solution.
The reaction of lead nitrate and NaOH resulted in
the production of Pb 2+ ions.
• Then thiourea was added which resulted in the
formation of PbS. Water was added only after mixing
the reactants.
IMPORTANCEOF ORDEROF MIXING0F REACTANTS
20. PREPARATION OF PbS USING LEAD ACETATE
(PRECURSOR SOLUTION)
• The first step in preparation of PbS using lead acetate is
preparation of 1 molar solution of lead acetate,thiourea,sodium
hydroxide
• The second step is to prepare precursor soluion using this
solution
• The third step is to immerse the substrate on the precursor
solution
• Order of mixing is important in this case also
21. OPTIMUM CONDITION
DIPPING TIME:65 MIN
At this condition thickness~200nm
When dipping time less than 65 min ,the films are not uniform
MOLARITY OF NaOH=0.55M
MOLARITY OF THIOUREA=0.1M
MOLARITY OF LEAD ACETATE/LEAD NITRATE=0.1M
AT ROOM TEMPERATURE
22. COMPARISON OF FILMS
We observed that uniformly deposited film is obtained
when we use lead acetate precursor solution. This film
was found to be more adhesive and pinhole free.
Lead nitrate precursor solution precipitated faster
than lead acetate solution. It is reported that slow
precipitation yielded better films.
24. THE HOT-PROBE METHOD
The "hot-probe" experiment provides a very simple
way to distinguish between n-type and p-type
semiconductors using a standard multimeter.
The experiment is performed by heating the
positive terminal of the standard multimeter.The
heated probe is hot probe and the other one is cold
probe. The two terminals are placed on the film,the
experimental setup is as shown in the figure
25. When applying the probes to n-type material one obtains a positive
current reading on the multimeter, while p-type material yields a
negative current.A . PbS thin film is observed to be p-type material.
26. STRUCTURAL CHRACTERISATION
X-ray crystallography is a tool used for identifying the atomic and
molecular structure of a crystal, in which the crystalline atoms cause a
beam of incident X-rays to diffract into many specific directions.
By measuring the angles and intensities of these diffracted beams, a
three-dimensional picture of the density of electrons within the crystal can
be produced.
Using this electron density, the mean positions of the atoms in the
crystal can be determined, as well as their chemical bonds, their disorder
and various other information.
The method also revealed the structure and function of many biological
molecules, including vitamins, drugs, proteins and nucleic acids such as
DNA.
X-ray crystallography is still the chief method for characterizing the
atomic structure of new materials and in discerning materials that appear
similar by other experiments
27. Crystals are regular arrays of atoms, and X-rays can be considered waves of
electromagnetic radiation. Atoms scatter X-ray waves, primarily through the atoms'
electrons.waves cancel one another out in most directions through destructive
interference, they add constructively in a few specific directions, determined by Bragg's
law:
Here d is the spacing between diffracting planes,
θ is the incident angle, n is any integer, and
λ is the wavelength of the beam.
28. THE DIAMETER OF THE CRYSTALLITES
we use the Debye-Scherrer formula to find the
diameter of the crystal.
Debye-Scherrer formula
D = 0.9λ/ β cosθ
Where,
D is the diameter of the crystallites forming the
film,
λ is the wavelength,
β is the FWHM (Full Width at Half Maximum) in
radians and
θ is the Bragg angle
29. Bragg Condition
2dsin θ= nλ
Where,
d is the interplanar distance,
n is the order of diffraction,
θ is the Bragg angle and
λ is the wavelength.
30. XRD of Sample of lead nitrate
20 30 40 50 60
0
50
100
150
200
250
300
350
INTENSITY[inarbitaryunits]
in degrees]
2θ(in
degrees)
(h k l)values
26.7 (1 1 1)
30.8 (2 0 0)
43.8 (2 2 0)
Inferences from XRD
• Thin films formed are
lead sulphide cubic
crystal and no other
phases are present.
• Using debye-scherrer
formula grain size is
calculated and is of the
order 41.9nm
• Using braggs condition
inter planar distance is
also calculated is equal
to 29nm
conc.of Pb(NO3)2 = 0.1M, conc.of SC(NH2)2 = 0.1M , conc.of NaoH=0.55M
31. 20 30 40 50 60
0
100
200
300
INTENSITY[inarbitaryunits]
[in degrees]
XRD of Sample of lead acetate
2θ(in
degrees)
(h k l)values
26.7 (1 1 1)
30.8 (2 0 0)
43.8 (2 2 0)
Inferences from XRD
•Thin films formed are
lead sulphide cubic crystal
and no other phases are
present.
•Using debye-scherrer
formula grain size is
calculated and is of the
order 45.44nm
•Using braggs condition
inter planar distance is
also calculated and equal
to28nm
•It is observed that
crystallinity is slightly
higher for lead acetate
conc.of Pb(CH3COO)2 = 0.1M,conc.of SC(NH2)2 =0.1M, conc.of NaoH =0.55M
32. EFFECT ON THE VARIATION OF LEAD CONCENTRATION ON
LEAD ACETATE PRECURSOR SOLUTION
For this the concentration of NaOH is fixed at 0.55M and that of thiourea at 0.1M and
the concentration of leadnitrate is varied from 0.1 to 0.22M
Sample name Molarity of NaOH(M) Molarity ofThiourea(M) Molarity of lead
acetate(M)
A 0.55 0.1 0.1
B 0.55 0.1 0.1
C 0.55 0.1 0.14
D 0.55 0.1 0.16
E 0.55 0.1 0.18
F 0.55 0.1 0.2
G 0.55 0.1 0.22
The best film was obtained at 0.1M concentration of lead acetate.Structural
characterization were done using x ray diffraction technique and electrical properties
are studied.
33. 20 30 40 50 60
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
INTENSITY[inarbitaryunits]
[in degrees]
20 30 40 50 60
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
INTENSITY[inarbitaryunits]
in degrees]
Here crystallinity was observed to be decreasing on increasing the Pb concentration in PbS
films.Decreases in crstallinity may be due to the removal of Pb2+ ions from the surface of
films.S.Seghaier et al reported that decrease in crystallinity in lead sulphide was due to the
depletion of Pb2+ ions resulting lower rate of deposition.Optimum lead content may be
reached even at 0.1M concentration of lead acetate (Reference : S. Seghaier, N. KamouN, R.
Brini, A.B. Amara, Materials Chemistry Physics 97 (2006) 71–80.)
STRUCTURAL ANALYSIS ON THE VARIATION OF LEAD
conc.of Pb(CH3COO)2 = 0.22M,conc.of SC(NH2)2 =0.1M,
conc.of NaoH =0.55M
conc.of Pb(CH3COO)2 =0.18M,conc.of SC(NH2)2 =
0.1M,conc.of NaoH =0.55M
34. Electrical contacts was given using silver paint of 5mm length in the form
of two end contacts having a distance of 5mm between them. Then
readings are taken by multimeters. Multimeters readings show that lead
sulphide films are conductive.
Resistivity and conductivity
Resistance, R = ρA
l
Therefore, Resistivity ρ = R x t x d
l
Where l is the length of the silver paint
d is the distance between two electrical contacts
t is the thickness of the film
here d and l are same
therefore ρ = R x t
here t,thickness of the film ~ 200nm
ρ = R x 200nm
ELECTRIAL CHARACTERISATION
35. Sample Resistance(MΩ) Resistivity( 10-3 Ωm) Conductivity(Ω-1m-1)
A
6.3 1260
0.79
C 5.2 1040 0.96
E 3.1 620 1.612
G 0.9 180 5.5
[lead concentration of samples:A = 0.1M, C = 0.14M , E = 0.18M , G = 0.22M ]
RESISTIVITY AND CONDUCTIVITY OF THE SAMPLES ON
VARYING THE LEAD CONCENTRATION IN LEAD ACETATE
36. MOLARITY OF LEAD VS CONDUCTIVITY
0
1
2
3
4
5
6
0 0.05 0.1 0.15 0.2 0.25
conductivity(ohm-1m-1)
concentration of lead (M)
From the graph we can understand that when concentration of lead increases
,there is a sharp increase in electrical conductivity which may be due to the greater
metal content.
37. • It was proved that films are PbS from the crystalline peaks of XRD and
there were three peaks corresponding to (1 1 1), (2 0 0) and (2 2 0)
orientations
• It was found out that the PbS films produced are p-type in nature
by hot probe method
• The resistance values of all PbS films can be measured using multimeter
and it means that our films are conductive. We have calculated resistivity
and conductivity of the films
• A clear increase in conductivity was observed on increasing the lead
concentration in PbS films,which may be due to the increase in metal
content
INFERENCES FROM THE PROJECT
• It is observed that the PbS films formed from lead acetate
precursor is more adherent than from lead nitrate
38. CBD is a cost effective method for the formation of
thin films.
The method does not involve heating or stirring.
The order of adding the reactants of the precursor
solution is important.
The films formed are conductive and crystalline in
nature.
The selection of precursor solutions also play a great
role in the formation of films.