%0 Journal Article %1 sando2018revisiting %A Sando, Daniel %A Carrétéro, Cécile %A Grisolia, Mathieu N %A Barthélémy, Agnès %A Nagarajan, Valanoor %A Bibes, Manuel %D 2018 %I Wiley Online Library %J Advanced Optical Materials %K BiFeO3 bandgap experiment ferroelectric_photovoltaics %N 2 %P 1700836 %T Revisiting the Optical Band Gap in Epitaxial BiFeO3 Thin Films %V 6 %X A detailed structural and optical band gap characterization study for more than 40 epitaxial bismuth ferrite (BiFeO3 —BFO) thin films, measured by X-ray diffraction, atomic force microscopy, and optical transmission spec- troscopy, is reported. The films are grown in different deposition systems to varying thicknesses (10–140 nm), on several substrates, and under different growth and cooling conditions. Using the results and literature data, first it is shown that the band gap measured by transmission is systematically lower than the gap found by ellipsometry, suggesting that sufficient caution must be exercised when comparing optical properties of BFO thin films. Then, statistical analysis is used to look for correlations between the band gap and structural parameters. While earlier works show the band gap to be sensitive to epitaxial (homogeneous) strain, it is found that it appears not to exhibit a dependence on inhomogeneous strain, out-of-plane lattice constant, or sub- strate/film interface roughness. Rather, it is found that surface roughness as well as film thickness generally tends to enhance the gap. Overall, the insen- sitivity of the band gap to structural parameters—aside from homogeneous strain—makes BiFeO3 largely immune to deviations in processing param- eters, which should be an asset for photonic devices based on this material.

@article{sando2018revisiting, abstract = {A detailed structural and optical band gap characterization study for more than 40 epitaxial bismuth ferrite (BiFeO3 —BFO) thin films, measured by X-ray diffraction, atomic force microscopy, and optical transmission spec- troscopy, is reported. The films are grown in different deposition systems to varying thicknesses (10–140 nm), on several substrates, and under different growth and cooling conditions. Using the results and literature data, first it is shown that the band gap measured by transmission is systematically lower than the gap found by ellipsometry, suggesting that sufficient caution must be exercised when comparing optical properties of BFO thin films. Then, statistical analysis is used to look for correlations between the band gap and structural parameters. While earlier works show the band gap to be sensitive to epitaxial (homogeneous) strain, it is found that it appears not to exhibit a dependence on inhomogeneous strain, out-of-plane lattice constant, or sub- strate/film interface roughness. Rather, it is found that surface roughness as well as film thickness generally tends to enhance the gap. Overall, the insen- sitivity of the band gap to structural parameters—aside from homogeneous strain—makes BiFeO3 largely immune to deviations in processing param- eters, which should be an asset for photonic devices based on this material.}, added-at = {2018-08-19T23:34:45.000+0200}, author = {Sando, Daniel and Carr{\'e}t{\'e}ro, C{\'e}cile and Grisolia, Mathieu N and Barth{\'e}l{\'e}my, Agn{\`e}s and Nagarajan, Valanoor and Bibes, Manuel}, biburl = {https://www.bibsonomy.org/bibtex/2754b659233f6e886485cdf515cc7aa4d/skoerbel}, interhash = {b0943bf54f513e8f9d14fe9f3adf4063}, intrahash = {754b659233f6e886485cdf515cc7aa4d}, journal = {Advanced Optical Materials}, keywords = {BiFeO3 bandgap experiment ferroelectric_photovoltaics}, number = 2, pages = 1700836, publisher = {Wiley Online Library}, timestamp = {2018-08-24T20:30:41.000+0200}, title = {Revisiting the Optical Band Gap in Epitaxial BiFeO3 Thin Films}, volume = 6, year = 2018 }