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  • TITLE
  • DEDICATION
  • DECLARATION
  • CERTIFICATE
  • ACKNOWLEDGEMENT
  • PREFACE
  • CONTENTS
  • I. REVIEW OF ELECTRICAL CONDUCTION AND OPTICAL STUDIES IN ELECTROCHROMIC AND PHOTOCHROMIC THIN FILMS
  • 1.1. Introduction
  • 1.2. Earlier work
  • 1.3. Electrochromism
  • 1.4. Photochromism
  • 1.5. Thermochromism
  • 1.6. Electrochromic devices
  • Fig I.1. Structure of a typical arrangement of different layers in an eIectrochromic window
  • 1.7. Energy band structure
  • Fig.l.2. Arrangement of different layers in an electrochrornic smart window
  • Fig.l.3. Energy band diagram for a typical insulator showing the valence band, conduction band and Fermi energy level.
  • 1.8. DC conduction mechanism in Metal-Insulator-Metal (MIM) films.
  • 1.8.1. High field conduction
  • 1.8.1.1 Electronic Conduction
  • i) Conduction by means of the conduction band.
  • ii) Tunneling processes
  • Fig.l.4. Energy band diagram of conduction processes ina thin film insulator in a high applied electric field.
  • Fig.I.5. Energy band diagram of the conduction processes in a thin insulator film at a low applied electric field.
  • iii) Impurity conduction
  • iv) Space-charge effect
  • 1.8.1.2 Ionic conduction
  • 1.8.2. Low field conduction
  • Fig.l.6. Energy band diagram showing band bending atinsulator electrode interface.
  • 1.8.2.1 Electronic impurity conduction
  • 1.8.2.2 Ionic conduction
  • 1.8.3. Temperature dependence
  • Fig.l.7. Arrhenius plot of conductivity of a typical insulator lor low fields.
  • References
  • II. APPARATUS AND EXPERIMENTAL TECHNIQUES USED IN THE PRESENT STUDY
  • 2.1 Introduction
  • 2.2 Methods of preparation
  • 2.2.1 Resistive heating evaporation
  • 2.2.2 Electron beam evaporation
  • Fig.2.1. Schematic diagram of an electron beam gun.
  • 2.3 Production of vacuum
  • 2.3.1 Oil-sealed rotary pump
  • Fig.2.2. Cross-section of oil-sealed rotary pump.
  • 2.3.2 Diffusion pump
  • Fig.2.3. Schematic diagram of cross-section diffusion pump,
  • 2.4 Vacuum coating plant
  • Fig.2.4. Schematic diagram of a vacuum coating unit.
  • Plate 2.1 Photograph of the thin film vaccum coating unit used in the Laboratory
  • 2.5 Substrate cleaning
  • 2.6 Preparation of films
  • 2.7 Preparation of MIM structure films.
  • Fig.2.5. Masks for Metal-Insulator-Metal film and its structural arrangement.
  • 2.8 Measurement of the thickness of films
  • 2.8.1 Optical Method (Multiple beam interferometry)
  • Tolanskys Fizeau fringes method
  • 2.8.2 Quartz crystal thickness monitor
  • Fig.2.6. Arrangement and figure pattern of Fizeaufringes.
  • Fig.2.7. Block diagram of a quartz crystal thickness monitor
  • 2.9 Measurement of electrical characteristics.
  • 2.9.1 Conductivity measurements
  • 2.9.2 Conductivity cell
  • Fig.2.8. Schematic diagram of electrical conductivity measurement
  • Fig.2.9. Schematic diagram of the cross-section ofthe conductivity cell.
  • 2.9.3 Electrometer
  • 2.9.4 Capacitance measurements
  • Fig.2.10. Measurement of resistance using Keithley programmable electrometer (model No. 617) in V/I mode.
  • 2.10 Measurement of optical characteristics
  • 2.10.1 UV-visible spectrophotometer
  • Fig.2.11. Electrical connection of Keithley programmable (model No. 617) electrometer for capacitance measurement.
  • 2.10.2 Infrared spectrophotometer
  • Fig.2.12. Optical diagram of the spectrophotometer
  • Fig.2.13. Block diagram of the electrical system of the spectrometer
  • 2.10.3 X-ray diffractometer
  • 2.10.4 Optical microscopy
  • 2.11 Measurement of thermal characteristics
  • 2.11.1 Thermogravimetry - D T A
  • 2.11.2 Thermo-EMF measurement
  • References
  • III. ELECTRICAL STUDIES IN MOLYBDENUM TRIOXIDE, VANADIUM PENTOXIDE, AND TITANIUM DIOXIDE FILMS.
  • 3.1 Introduction
  • 3.2 Experiment
  • 3.3. Results and discussion.
  • 3.3.1 DC electrical conductivity in coplanar geometry
  • Fig.3.1. Plot of log σ vs. 1/T for MoO3 films of thicknesses 165nm, 187nm, and 208nm coplanar geometry
  • Fig.3.2. Plot of log σ vs. 1/T for V2O2 films of thicknesses 45nm, 74nm, and 164nm in coplanar geometry
  • Fig.3.3. Plot of log σ vs 1/T for TiO2 films of thicknesses 94nm, 110nm and 153nm in coplanar geometry
  • Fig.3.4. Plot of log (σ T) vs. 1/T for MoO3 films of thicknesses 126nm, 150nm, and 163nm according to Motts formula.
  • Fig.3.5. Plot of log (σ T) vs. 1/T for V2O5 films of thicknesses 164nm, 254nm, and 299nm according to Motts formula.
  • 3.3.2 DC electrical conductivity in sandwich geometry
  • Fig.3.6. Plot of log (σ T) vs. I/T for conductivity of TiO2 films of thicknesses 94nm, 11Onm, and 153nm according to Motts formula.
  • Fig.3.7. Plot of log σ vs. 1/T for MoO3 film of thicknesses 131nm, 156nm, and 194nm in sandwich geometry
  • Fig.3.8. Plot of σ log vs. 1/T for V2O5 films of thicknesses 127nm, 143nm, and 164 nm sandwich geometry
  • Fig.3.9. Plot of log σ vs. 1/T for TiO2 film of thicknesses 60nm, 110nm and 153nm in sandwich geometry
  • Fig.3.10. Plot of log (σ T) vs. 1/T for MoO3 films of thicknesses 131nm 156nm, 194nm in sandwich geometry according to Motts formula.
  • Fig.3.11. Plot of log (σ T) vs. l/T for V2O5 films of thicknesses 127nm, 143nm, and 164nm in sandwich geometry according to Motts formula.
  • 3.3.3 Field dependent electrical conduction in Metal-Insulator-Metal structure
  • Fig.3.12. Plot of log (σ T) vs. 1/T for TiO2 films of thicknesses 60nm, 11Onm, and 153nm in sandwich geometry according to Motts formula.
  • Fig. 3.13. Plot of log I vs. V 1/2 for A1-MoO3 -A1 films of thicknesses 156nm, 181nm, and 194nm at room temperature.
  • Fig.3.14. Plot of in I vs. V1/2 for AI-V-0 -A1 films of 5V 0 thicknesses 113nm, 127nm, and 162nm at room temperature.
  • Fig.3.15.Plot of log I vs V1/2 for Al-TiO2 -Al films of TiO2 thicknesses = 60nm, 110nm. and 153 nm at room temperature.
  • Fig.3.16. plot of In (1/T2) v s 103/T at different biasing voltages for Al- MoO3 -Al film of MoO3 thickness 156nm
  • Fig.3.17. Plot of In (1/T2) vs. 103/T at different biasing voltages for Al-V2O3-Al film with V2O3 thickness 162nm
  • Fig.3.18. Plot of In (I/T2) vs. 10 /T at different biasing voltages for Al-TiO2 -Al film with TiO2 thickness 153nm.
  • Fig.3.19. Plot of in I with 10/T at different biasing voltages for Al-MoO3-Al film with MoO3 thickness 156nm.
  • Fig.3.19a. Plot of activation energy vs. biasing voltages for Al-MoO3-AI sandwich structure with MoO3 thickness = 156nm
  • Fig.3.20 Plot of In I with 10/T at different biasing voltages for Al-V2O5-al film with V2O5 thickness 162nm
  • Fig.3.20a. Plot of activation energy vs. biasing voltages for Al-V2O5 -Al sandwich structure with V2O5 thickness 162nm.
  • Fig.3.21. Plot of in I vs.10/T at different biasing voltages for AI-TiO2-Al film with TiO2 thickness 153nm.
  • Fig.3.21a. Plot of activation energy vs.biasing voltages for Al-TiO3 -Al sandwich structure of TiO2 thickness = 153nm
  • 3.3.4. Studies of capacitance in Metal-Insulator-Metal structure.
  • Fig.3.22. Plot of capacitance vs.temperature for Al-MoO3 -Al with MoO3 thicknesses = 131nm, 156nm and 194 nm.
  • Fig.3.23. Plot of capacitance vs. temperature for A l -V2O5 -Al with V2O5 thicknesses = 81nm, 113nm, and 164nm
  • Fig.3.24. Plot of capacitance vs. temperature for Al-TiO2 -Al with TiO2 thicknesses = 60nm, 111nm, and 153nm.
  • Fig.3.25. Plot of capacitance vs. inverse of thicknesses for MoO3 film.
  • Fig.3.26. Plot of capacitance vs inverse of thickness for V2O3 film.
  • Fig.3.27. Plot of capacitance vs. inverse of thickness for TiO2 film
  • 3.4. Conclusion
  • Fig.3.28. Plot In I vs. In V for Al-MoO3-Al films with MoO3 thickness 156nm, 181nm & 194nm
  • Fig.3.29. Plot of lnl with In V for Al-V2O5-Al film of V2O5 thicknesses. 81nm. 113nm, 127nm, and I62nm.
  • Fig.3.30. Plot of InI with InV for AI-TiO2 -Al film of TiO2 thicknesses 60nm. 111nm and 153nm.
  • References
  • IV. OPTICAL STUDIES IN MOLYBDENUM TRIOXIDE, VANADIUM PENTOXIDE, AND TITANIUM DIOXIDE FILMS
  • 4.1 Introduction
  • 4.2 Theory
  • Fig.4.1. Reflection and transmission of light by a single film
  • Fig.4.2. Plot of transmittance spectra vs.λ for MoO3 film of thickness 61nm.
  • Fig.4.3. Plot of transmittance spectra vs. λ for V2O5 film of thickness 208nm.
  • 4.3 Experiment
  • 4.4 Results and discussion
  • 4.4.1 Optical constants
  • Fig.4.4. Plot of n and k vs. λ for MoO3 film.
  • Fig.4.5. Plot of n and k vs. λ for V2O5 films
  • 4.4.2 optical band gap
  • Fig.4.6a. Transmission spectra of MoO3 film of thickness 187nm as a function of wavelength before and after UV irradiation.
  • Fig.4.6b. Transmission spectra of MoO3 film of thickness 211nm as a function of wavelength before and after UV irradiation in alcohol vapour.
  • Fig.4.7. Transmission spectra of V2O5 film of thickness 129 nm as a function of wavelength before and after UV irradiation.
  • Fig.4.8. Transmission spectra of TiO2 film of thickness 94 nm as a function of wavelength before and after UV irradiation.
  • Fig.4.9a. Plot of (α ħ ω) vs. ħ ω for MoO3 film in air
  • Fig.4.9b. Plot of (α ħ ω) vs. ħ ω for MoO3 film in alcohol vapour
  • Fig.4.10. Plot of (α ħ ω) 2 / 3 vs. ħ ω for V2O5 film
  • Fig.4.11 Plot of (α ħ ω) vs. ħ ω and (α ħ ω) vs ħ ω for TiO2 film
  • 4.4.3 Infrared spectra of MoO3, V205, and TiO2 films
  • Fig.4.12. IR spectra of MoO3 film of thickness 134 nm.
  • Fig.4.13.K spectra of V2O5 film of thickness 127nm.
  • Fig.4.14.K spectra of TiO2 film of thickness 60nm.
  • 4.4.4 X-ray diffraction studies
  • Fig.4.15. XRD pattern of MoO3 film; (a) as-deposited, film (b) film annealed at 250°c
  • 4.4.5 Morphological studies
  • Fig.4.16. Micrographs of MoO3 film at (a) room temperature.
  • 4.4.6 DC electrical conductivity while UV irradiation
  • Fig.4.17.Plot of σ vs. UV irradiation time for MoO3 film of thickness 208 nm; (a) after starting irradiation (b) after terminating irradiation.
  • Fig.4.18. Plot of σ vs. UV irradiation time for V2O5 film of thickness 164nm (a) after starting UV irradiation, (b) after terminating UV irradiation.
  • Fig.4.19. Plot of σ vs. TiO2 UV irradiation time for TiO2 of thickness 106nm. (a) after starting UV irradiation (b) after terminating UV irradiation
  • 4.5. Conclusion
  • References
  • V. THERMAL STUDIES IN MOLYBDENUM TRIOXIDE AND VANADIUM PENTOXIDE FILMS
  • 5.1. Introduction
  • 5.2. Experiment
  • 5.3. Results and discussion
  • 5.3.1.TG-DTA studies
  • Fig.5.1. V2O5 thermo-emf study set-up.
  • Fig.5.2. TG-DTA curve of MoO3 film.
  • 5.3.2.Thermo emf studies
  • Fig.5.3. Plot of thermo-emf vs.absolute temperature for Al-V2O5 film for various thickness.
  • Fig.5.4. Plot of TEP vs. inverse of temperature for AI-V2O5
  • 5.4. Conclusion.
  • References
  • VI. ELECTRICAL AND OPTICAL STUDIES OF MIXED OXIDE SYSTEMS OF MoO3 AND V205 THIN FILMS
  • 6.1.Introduction
  • 6.2.Experiment
  • 6.3 Results and discussion:
  • Fig.6.1. Plot of log σ vs 1000/T for MoO3 -V2O5 system in different molar concentrations. Thickness of the films is between 190-200 nm.
  • Fig.6.2. Transmittance spectra of MoO3 -V2O5 mixed mixed system in different molar concentrations as a function of wavelength.Thickness of the film is between 190-210nm.
  • Fig.6.3. Plot of (αħω) YS. (ħω) for different molar concentrations of MoO3 and V2O5 mtxed system.The thickness of the film is 190-21Onm.
  • Fig.6.4. Plot of n and k vs. wavelength (λ) for 90% MoO3: 10% V2O5 mixed system of thickness 194nm.
  • Fig.6.5. IR spectra of MoO3-V2O5 mixed systems in different molar concentrations and thickness of the range of 190-210.
  • 6.4 conclusion
  • References
  • VII. DESIGN AND FABRICATION OF ELECTROCHROMIC WINDOWS USING MOLYBDENUM TRIOXIDE AND VANADIUM PENTOXIDE
  • 7.1 Introduction
  • 7.2 Operating principle
  • Fig.7.1. Optical properties of idealized
  • 7.3 Experiment
  • Fig.7.2. All-solid type electrochromic window structure using MoO3
  • 7.4 Results and Discussion
  • Fig.7.3. Lamination type window structure using MoO3-V2O5.
  • Fig.7.4. Transmission spectra as a function of wavelength for different applied voltages for all-solid type window.
  • Fig.7.5. Transmission spectra as a function of wavelength for different applied voltages for lamination type window.
  • 7.5 Conclusion
  • References