Growth and photo-response of (110) oriented BaBiO₃ films on SrTiO₃ (001) substrates

Preferred orientation and optical responses were studied for BaBiO₃ films grown by pulsed laser deposition. BaBiO₃ films have a monoclinic symmetry I2/m, with the (110) preferred orientation on SrTiO₃ (001) substrates. From the transmittance spectra of BaBiO₃ films, optical bandgaps were estimated to be around 2.3 eV for direct transition and 2.1 eV for indirect transition. From the photo-response transient characteristics of the film, the decay time of photoconductivity was estimated to be 0.48 sec. The relation between ultraviolet light-induced photoconductivity and film crystallinity is clarified. The photoconductivity became low for BaBiO₃ films with high crystalline quality which was the opposite result for the case of TiO₂ films.