Carrier recombination in SrTiO3 single crystals: impacts of crystal faces and Nb doping

We observed the carrier recombination in SrTiO3 single crystals with several crystal faces and Nd doping concentrations using time-resolved photoluminescence and microwave photoconductivity decay methods. The shapes of the decay curves were independent of the excited carrier concentrations, and thus the carriers recombined through the Shockley-Read-Hall and surface recombination processes. From the measurements for different crystal faces, we found that, although the surface recombination is significant for the (100), (110), and (111) faces, they have similar surface recombination velocities of similar to 10(6) cm s(-1). Therefore, as photocatalysts, the shape of the materials has a minor effect on the energy conversion efficiency. Based on the dependence of the Nb doping concentration, a high doping concentration significantly enhances the carrier recombination, whereas a moderate Nb doping induces only a slight reduction in the time constants of the carrier decay. In addition, the time constant increases with temperature, and thus moderate Nb doping will have a positive effect on the energy conversion efficiency of SrTiO3 photocatalysts at high temperatures.

Automated summary

The carrier recombination in SrTiO3 single crystals with different crystal faces and Nd doping concentrations was studied using time-resolved photoluminescence and microwave photoconductivity decay methods. It was found that carriers recombined through the Shockley-Read-Hall and surface recombination processes, with surface recombination velocities being similar for different crystal faces. Additionally, higher Nb doping concentrations significantly enhanced carrier recombination, while moderate Nb doping only slightly reduced carrier decay time constants.