Photogenerated carriers in SrTiO3 probed by mid-infrared absorption

摘要

Infrared absorption spectra of SrTiO3 have been measured under above-band-gap photoexcitations to study the properties of photogenerated carriers, which should play important roles in previously reported photoinduced phenomena in SrTiO3. A broad absorption band appears over the entire mid-infrared region under photoexcitation, which is attributed to absorption by the photogenerated carriers occupying in-gap states. The photoinduced absorption is strongly dependent on temperature even below 35 K, where the average photocarrier density is nearly constant. The data show that the density of in-gap states occupied by the photocarriers is high and distributed over a wide energy range extending to the band edges.