Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Visible light carrier generation in co-doped epitaxial titanate films   Perovskite titanates such as SrTiO$_{3}$ (STO) exhibit a wide range of
important functional properties, including high electron mobility,
ferroelectricity, and excellent photocatalytic performance. The wide optical
band gap of titanates limits their use in these applications, however, making
them ill-suited for integration into solar energy harvesting technologies. Our
recent work has shown that by doping STO with equal concentrations of La and Cr
we can enhance visible light absorption in epitaxial thin films while avoiding
any compensating defects. In this work, we explore the optical properties of
photoexcited carriers in these films. Using spectroscopic ellipsometry, we show
that the Cr$^{3+}$ dopants, which produce electronic states immediately above
the top of the O 2p valence band in STO reduce the direct band gap of the
material from 3.75 eV to between 2.4 and 2.7 eV depending on doping levels.
Transient reflectance spectroscopy measurements are in agreement with the
observations from ellipsometry and confirm that optically generated carriers
are present for longer than 2 ns. Finally, through photoelectrochemical
methylene blue degradation measurements, we show that these co-doped films
exhibit enhanced visible light photocatalysis when compared to pure STO.

32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc