jz0c02330_si_001.pdf (13.99 MB)
Micro-Heterogeneous Annihilation Dynamics of Self-Trapped Excitons in Hematite Single Crystals
journal contribution
posted on 2020-09-04, 17:09 authored by Hongyan Liao, Yunyan Fan, Yumei Lin, Kang Wang, Renfu Li, Xueyuan Chen, Kelvin H. L. Zhang, Ye YangThe
Auger recombination in bulk semiconductors can quickly depopulate
the charge carriers in a nonradiative way, which, fortunately, only
has a detrimental impact on optoelectronic device performance under
the condition of high carrier density because the restriction arising
from concurrent momentum and energy conservation limits the Auger
rate. Here, we surprisingly observed enhanced Auger recombination
in an α-Fe2O3 single crystal, a wide bandgap
semiconductor with low carrier mobility. The Auger process was ascribed
to the Coulombically coupled self-trapped excitons (STEs), and the
relaxation of momentum conservation due to the strong spatial localization
of these STEs should account for the enhancement. The STE-density
dependent kinetics suggested that the strong polaronic effect could
cause a micro-heterogeneous distribution of STEs in a high-quality
bulk single crystal, which also gave rise to the micro-heterogeneous
annihilation dynamics, and a stochastic recombination model was developed
and successfully described the STE annihilation dynamics.