Effect of oxygen partial pressure on structural and optical properties of pulsed laser deposited CaBi < inf > 4 < /inf > Ti < inf > 4 < /inf > O < inf > 15 < /inf > thin films

Abstract

The influence of oxygen partial pressure (OPP) on the structural and optical properties of CaBi 4 Ti 4 O 15 (CBTi) thin films deposited by pulsed laser deposition have been investigated in the range of 0.1 mbar to 7.8 × 10 −3 mbar. The structural properties show all the films are polycystlline in nature with orthorombic structure. The optical transmission of the films is in the range of 60–90%. A slight shift in transmission threshold towards higher wavelength region with an increase in O 2 pressure reveals the systematic reduction in the optical band gap energy (3.69 to 3.59 eV) of the films. Raman studies confirm the phase formation and presence of stresses in the films. It is suggested that the OPP played a key role in controlling crystallinity, morphology, chemical composition and optical properties in CBTi thin films.