Optical and electrical properties of spray pyrolysis deposited nano-crystalline BiFeO3 films

The nano-crystalline BiFeO3 were prepared under controlled substrate temperature by spray pyrolysis method. Their structural, optical and electrical properties were studied and correlated. A blueshift (Δλ ∼ 8.17 nm) in the absorbance peaks was observed in the films with decrease in grain size. The absorption coefficient spectra show defect transitions at 1.9 and 2.3 eV in large grain size films due to oxygen vacancies. The lowest leakage was observed in smaller grain size (< 20 nm) films due to negligible oxygen vacancies, smooth surface roughness and large energy bang gap. The Poole-Frankel conduction mechanism has been found to be the predominant mechanism for the leakage current.