Ultrafast transient reflectance of epitaxial semiconducting perovskite thin films

作者：Smolin S Y; Scafetta M D; Guglietta G W; Baxter J B^*; May S J

来源：Applied Physics Letters, 2014, 105(2): 022103.

DOI：10.1063/1.48902411

Ultrafast pump-probe transient reflectance (TR) spectroscopy was used to study carrier dynamics in an epitaxial perovskite oxide thin film of LaFeO3 (LFO) with a thickness of 40 unit cells (16 nm) grown by molecular beam epitaxy on (LaAlO3)(0.3)(Sr2AlTaO6)(0.7) (LSAT). TR spectroscopy shows two negative transients in reflectance with local maxima at similar to 2,5 eV and similar to 3.5 eV which correspond to two optical transitions in LFO as determined by ellipsometry. The kinetics at these transients were best fit with an exponential decay model with fast (5-40 ps), medium (similar to 200 ps), and slow (similar to 3 ns) components that we attribute mainly to recombination of photoexcited carriers, Moreover, these reflectance transients did not completely decay within the observable time window, indicating that similar to 10% of photoexcited carriers exist for at least 3 ns. This work illustrates that TR spectroscopy can be performed on thin (%26lt;20 am) epitaxial oxide films to provide a quantitative understanding of recombination lifetimes, which are important parameters for the potential utilization of perovskite films in photovoltaic and photocatalytic applications.

• 出版日期2014-7-14