Anomalous Behaviour in Structural and Optical Properties of Cr and N co- doped TiO 2 thin films Under Thermally Induced Conditions synthesized by Spin Coating

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Abstract This study investigates the transformative effects of chromium and nitrogen doping on the structural and optical characteristics of TiO₂ thin films. Intriguing results are obtained by analysing XRD patterns, FTIR spectroscopy, RBS, EDS, UV-vis transmission spectra, and bandgap studies. The XRD analysis reveals the development of mixed phases, with notable phase transitions observed upon doping in TiO₂ thin films and the occurrence of Ti₂O₃ peak, suggesting potential advantages such as enhanced conductivity or catalytic activity. FTIR spectroscopy confirms the C-O stretching group at 1102 cm⁻¹ and characteristic peaks in the fingerprint region at 613 cm⁻¹ and 435 cm⁻¹, indicating titanium-oxygen bonds and the incorporation of dopants into the TiO2 lattice. RBS spectra show that the pristine thin films have a thickness of 268 nm, which increases to 270 nm upon doping. UV-Vis transmission spectra unveil alterations in transparency and absorbance, with chromium and nitrogen dopants significantly impacting optical properties. Notably, bandgap measurements highlight the fascinating phenomenon of bandgap narrowing attributed to the substitution of lattice oxygen with nitrogen atoms. The bandgap energy of the Pristine film is 3.25 eV, which decreases to 2.28 eV after increasing chromium doping. The nitrogen-doped 7Cr: TiO₂ thin film showed a bandgap energy of 2.81 eV. This study illuminates the complex interplay between doping and TiO₂ thin film properties, offering valuable insights for optoelectronic applications and materials science advancements.