Layer-effects on electrical and photovoltaic properties of Aurivillius-type Srn-3Bi4TinO3n+3 (n = 3, 5) films grown by pulsed laser deposition

Bi4Ti3O12 (BTO) and Sr2Bi4Ti5O18 (SBT) materials belonging to the Aurivillius family materials were deposited on Pt/Ti/SiO2/Si substrates via pulsed laser deposition technology. The XRD, SEM, EDX, FTIR-ATR, ferroelectric properties, piezoelectric properties, absorption spectra, reflection spectra, and ellipsometry characterization were used to compare the differences between the two materials and find out the relationship between them. The relative atomic displacement of the two materials, calculated from the atomic coordinates, which explain the poor ferroelectric properties of SBT than BTO materials. Computing of the absorption spectra revealed that the band gap of the BTO sample is 2.51 eV and the SBT sample is 2.23 eV, probably due to the greater stress of the BTO’s fluorite structure to the oxygen octahedra. In addition, the band gap (2.48 eV) and the density of state of the BTO were calculated by first principles method to assist in the analysis of the experimental data. Through the comparison of the two materials, the reason of the difference in the performance of Aurivillius family materials is analyzed from the atomic level, which provides the theoretical basis for the application of Aurivillius family materials in random access memory, sensor and optical devices.