Photogenerated Carriers in SrTiO3 Probed by Mid-Infrared Absorption

TL;DR

This study investigates the properties of photogenerated carriers in SrTiO3 using mid-infrared absorption spectra, revealing a broad absorption band and a high density of in-gap states influenced by photoexcitation.

Contribution

It provides detailed analysis of photoinduced absorption in SrTiO3, highlighting the existence of in-gap states and their energy, temperature, and power dependences, which advances understanding of photoinduced phenomena.

Findings

Broad mid-infrared absorption under photoexcitation

Existence of high-density in-gap states for carriers

Photoinduced absorption depends on energy, temperature, and power

Abstract

Infrared absorption spectra of SrTiO$_3$ 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 SrTiO$_3$. A broad absorption band appears over the entire mid-infrared region under photoexcitation. Detailed energy, temperature, and excitation power dependences of the photoinduced absorption are reported. This photo-induced absorption is attributed to the intragap excitations of the photogenerated carriers. The data show the existence of a high density of in-gap states for the photocarriers, which extends over a wide energy range starting from the conduction and valence band edges.