Tuning the Charge-Transport Properties of CeTiO₃ Thin Films through Controllable Phase Transformations Induced by the JNSP Technique

Abstract

CeTiO3 thin films were synthesized by jet nebulizer spray pyrolysis (JNSP) at substrate temperatures of 350, 400, and 450 °C to investigate temperature-dependent structural, optical, morphological, and electrical properties for photodiode applications. X-ray diffraction analysis confirmed temperature-induced phase evolution and showed an increase in average crystallite size from 11.46 to 12.98 nm, accompanied by a reduction in dislocation density. FESEM observations revealed progressive grain growth and improved film densification, with average particle size increasing from approximately 17 to 35 nm. UV–Vis analysis demonstrated a decrease in optical band gap from 2.96 to 2.64 eV as the substrate temperature increased, indicating enhanced visible-light absorption. XPS confirmed the presence of Ce, Ti, and O with mixed Ce3+/Ce4+ states and predominantly Ti4+. CeTiO3/p-Si photodiodes were fabricated and evaluated through current-voltage measurements under illumination. Device performance improved with increasing deposition temperature, with the 450 °C sample exhibiting the lowest ideality factor of 1.991, the highest barrier height of 0.411 eV, responsivity of 5.97 mA/W, quantum efficiency of 8.89%, and detectivity of 5.66 × 10^10 Jones. These results demonstrate that substrate-temperature control effectively tunes CeTiO3 thin-film properties and enhances photodiode performance. The optimized films therefore show strong potential for oxide-based optoelectronic and photodetection device applications.