1. Republic of IraqMinistry of Higher Education and Scientific Research University of Al-Mustansiriya College of Education A thesis submitted BySarmad Sabih Kaduory Al-ObaidiSupervised byDr.Ali Ahmed Yousif Al-Shammari(Assistant Professor)

2. Abstract Nanostructured TiO2 thin films are grown by pulsed laserdeposition (PLD) technique on glass substrates. TiO2 thinfilms are then annealed at 400-600 C in air for a period of 2hours. Effect of annealing on the structural, morphologicaland optical properties are studied. The results of the X-ray testing show that all nanostructurestetragonal are polycrystalline, also these results show that increasing in grain size with increasing of annealing temperature. The XRD results also reveal that the deposited thin film and annealed at 400 C of TiO2 have anatase phase. Thin films annealed at 500 C and 600 C have mixed anatase and rutile phase. 3. AFM measurements confirmed that the films grown by thistechnique have good crystalline and homogeneous surface.The Root Mean Square (RMS) value of thin films, surfaceroughness increased with increasing annealing temperature. From UV-VIS spectrophotometer measurements, the opticaltransmission results shows that the transmission overthan ~65% which decrease with the increasing of annealingtemperatures. The allowed indirect optical band gap of thefilms was estimated to be in the range from 3.49 to 3.1 eV.The allowed direct band gap was found to decrease from3.74 to 3.55 eV with the increase of annealing temperature.The refractive index of the films was found from 2.1-2.8 inthe range from 350nm to 900nm. The extinction coefficient,real and imaginary parts of the dielectric constant increasewith annealing temperature. 4. Why titanium dioxide (TiO2)?Non-toxic, inexpensive, highly photoactive, and easilysynthesized and handled. Highly photostable. High electro-chemical properties and high chemical stability. Wide band gap (Eg 3 eV). High refractive index - up to 2.7 (at wavelength of 600nm). High dielectric constant and hardness. 5. The Crystal Structure of TiO2 Anatase RutileBrookite form is tetragonal form is tetragonal form is orthorhombic 3.9 gm/cm34.23 gm/cm3 4.13 gm/cm3a = b = 3.7710 and a = b = 4.5933 and a = 9.18 , b = 5.447 c = 9.430 c = 2.9592 and c = 5.145 n= 2.5612n= 2.605n= 2.5831 6. Applications of Nanostructured TiO2 Hydrophilic properties for environmental applications, suchas air purification, sterilization, anti fogging, and selfcleaning. Biomedical applications . Photocatalysis. 7. Dye-sensitized solar cells (DSSC). TiO2/polymer nanocomposites. Gas sensors. 8. Mechanism of Pulsed Laser DepositionThe mechanism of the PLD process can be expressed in threesteps : The interaction of the laser beam and target. Plasma Plume Formation. Nucleation and growth of thin films. 9. Pulsed laser deposition (PLD) The target material isablated by a Nd: YAGNd: YAGLaser. The ejected materialforms a plasma plumeand expands across tothe substrate where it is Halogendeposited as a film.Lamp The substrate is heatedby a halogen lamp. A background gas isused to control the plumestoichiometry anddynamics. 10. Aim of the Work Initially, the series of samples has been prepared by PLDtechnique at different technological conditions on glasssubstrates. We study the preparation condition such as, substratetemperature, oxygen pressure, energy laser influence duringdeposition, as well as the concentration into the target onthe structure, morphology (Atomic Force Microscopy(AFM)), and XRD. Also the optical properties for depositedfilms. Then, we study the effect of annealing temperature onstructural and optical properties of TiO2 films. 11. Experimental Work 12. Experimental work Thin filmsBy PLD Annealing films at :400 oC, 500 oC& 600 oCThickness Structural Opticalof thin films Properties PropertiesOptical T, A, , Eg, n,interferometer XRD & AFMk,r, i & method 13. Target preparation of TiO2(a) before(b) after The target before and after being 14. Parameters Used Laser model: Q-switched Nd: YAG Laser Second Harmonic Generation (SHG). Laser wavelength 532 nm. Energy density 0.4 J/cm2. Pulse duration 10 ns. Substrate temperature of 300 C. Pressure of 10-2 mbar. 15. Pulsed Laser Deposition (PLD) 16. Nanostructured TiO2 Thin films 17. Characterization measurements1. Thickness measurement 18. Characterization measurements2. X-ray Diffraction (XRD) Shimadzu 6000 made in Japan 19. Characterization measurements3. Atomic Force Microscopy 4. Optical measurements (AFM) 20. Results 21. X-ray Diffraction All the films were polycrystalline. Good agreement with JCPD data card Films annealed at 500 C and 600 C have mixed anatase and rutile phase structure. 22. Table 1: Lattice constants and interpllanar spacing of TiO2 films.Temperature2InterplanarLattice constant (hkl)c/a ( oC) (degree)spacing, d acAs-deposited25.27 A(101)3.153.3439/2.842 at 300 37.83 A(004)2.37/9.505025.2A(101)3.53 3.8/400 37.81 A(004)2.37/9.5098 3.50248.1A(200)1.893.7803/25.17 A(101)3.53 3.8/37.79 A(004)2.38/9.5147500 3.50348.12 A(200)1.893.7788/27.47 R(110)3.244.5881/25.11 A(101)3.543.8170/37.72 A(004)2.38/9.531760048 A(200)1.893.7877/ 2.49727.41 R(110)3.254.5979/54.35 R(211)1.68/2.9484 23. Full Width at Half Maximums (FWHM) decreases with increasing of annealing temperatureGrain size increase with increasing of annealing temperatureValues of texture coefficient decrease with increasing of annealing temperature Table 2: The obtained result of the structural properties from XRD for TiO2 thin films. Main Temperature2Stress Ss Strain (hkl) FWHM Grain Texture Tc( oC) (degree) (GPa)10-3) Size (nm) As-deposited25.27 A(101)0.450 19.02 0.2180.93541.813at 300 37.83 A(004)0.440 19.94 25.2A(101)0.421 20.19 400 37.81 A(004)0.0980.4225 0.412 21.271.126 48.1A(200)0.410 22.16 25.17 A(101)0.352 24.16 37.79 A(004)0.400 21.94 500 -0.0190.0841.154 48.12 A(200)0.349 25.99 27.47 R(110)0.334 25.59 25.11 A(101)0.301 28.25 37.72 A(004)-0.435 1.8709 0.288 30.43 60048 A(200)0.338 26.880.952 27.41 R(110)0.315 27.13 0.849 3.640 54.35 R(211)0.293 31.85 24. Atomic Force Microscopy (AFM) 25. AFMTable 3: Morphological characteristicsfrom AFM images for TiO2 thin film. The root mean square Root Mean SquareTemperature (oC) Roughness average(RMS)(RMS)and surface (nm)(nm)roughnessincreased As-deposited at 46.560.5300 withincreasingof40076.695annealing temperature50084.310560088.6114 26. Optical Properties 1. Optical Transmission (T)Average transmittance of as-deposited TiO2 films is about 65% in the near-infrared regionFor all the films transmittance decreases with increasing of annealing temperature 27. Optical Properties2. Optical Absorption (A) 28. Optical Properties 3. Optical Absorption Coefficient ()The absorption coefficient () is increasing with the annealing temperature increasing 29. Optical Properties4. Optical Energy Gap (Eg) 30. Optical Properties4. Optical Energy Gap (Eg)Table 4: Shows allowed direct band gap and allowed indirect band gap for differentFrom table 4. it can be annealing temperatures of TiO2 thin films. observed that (Eg) isdecreasing with theAllowed direct Allowed indirectincreasing of annealingTemperature (oC)bandbandgap (eV)gap (eV)temperature for allfilms.As-deposited at 3003.743.49 400 3.7 3.39 500 3.683.35 600 3.553.1 31. Optical Properties5. The values of the refractive index 6. Extinction coefficient (Ko) increasing (n) for the films of differentwithincreasing ofannealing annealing temperatures vary in thetemperature. range from 2.1 to 2.8. 32. Optical Properties 7. The Dielectric Constants ( r, i) Real part and imaginary part increases when the annealing temperatureincreasing. 33. Optical Properties 8. Optical Conductivity () The optical conductivity of the films increases with increasing of annealingtemperature. 34. Conclusion The XRD results reveal that the deposited thin film and annealed at 400 C of TiO2have a good nanocrystalline tetragonal anatase phase structure. Thin films annealedat 500 C and 600 C have mixed anatase and rutile phase structure. The AFM results show the slow growth of crystallite sizes for the as-grown films andannealed films from 400 to 600 C. The root mean square (RMS) is found to increasefrom 50.5 to 114 nm as the annealing temperature is increased up to 600 C. The average transmittance (T) of deposited TiO2 films is about 65% in the near-infrared region. The film annealed at 600 C has the least transmittance among thefilms, therefore; the film is good to be detector within ultra-violet region range. Theoptical absorption coefficient () of TiO2 films is about (>104cm-1), thus absorptioncoefficient has higher increase at wavelength (