Up-conversion photoluminescence and dielectric properties of pulsed-laser-ablated (Bi, Er)4Ti3O12 thin films grown with three different orientations

Epitaxial (001)-, (118)-, and (104)-oriented Bi3.95Er0.05Ti3O12 (BErT) films were reproducibly obtained by pulsed-laser-ablated method, and the (100)-, (110)-, and (111)-oriented Nb-doped SrTiO3 (NSTO) was used as substrates, respectively. X-ray diffraction indicated that the epitaxial orientation relation BErT (001)||NSTO (100), BErT (118)||NSTO (110), and BErT (104)||NSTO (111) are effective for BErT thin films on NSTO substrates in all cases. The spectral analysis indicates that the up-conversion (UC) luminescence spectra of thin films contain a red light emission band centered at 660 nm and two green light emission bands centered at 525 and 548 nm. Furthermore, a strong orientation-dependent UC luminescence was also observed. The (104)-oriented thin film reveals an approximately 7 times higher fluorescence intensity than that of the (118)-oriented thin film, which in turn has an about 3 times higher fluorescence intensity than the (001)-oriented BErT thin film. The dependence of photoluminescence on the film orientation can be attributed to the reflection of aligned grains toward incident light. Accordingly, the dielectric constant of (104)-, (118)-, and (001)-oriented BErT films is 195, 183, and 158 at the frequency of 100 kHz, respectively, thus demonstrating the dielectric anisotropy.

Automated summary

Epitaxial (001)-, (118)-, and (104)-oriented BErT films were obtained using pulsed-laser-ablated method, and their up-conversion luminescence intensity was found to be orientation-dependent due to the reflection of aligned grains towards incident light.