Ultrafast Dynamics of Defect-Assisted Auger Process in PdSe2 Films: Synergistic Interaction between Defect Trapping and Auger Effect

Di Li; Wenjie Zhang; Peng Suo; Jiaming Chen; Kaiwen Sun; Yuqing Zou; Hong Ma; Xian Lin; Xiaona Yan; Saifeng Zhang; Bo Li; Guohong Ma

doi:10.1021/acs.jpclett.2c00315

Ultrafast Dynamics of Defect-Assisted Auger Process in PdSe₂ Films: Synergistic Interaction between Defect Trapping and Auger Effect

J Phys Chem Lett. 2022 Mar 31;13(12):2757-2764. doi: 10.1021/acs.jpclett.2c00315. Epub 2022 Mar 22.

Authors

Di Li¹, Wenjie Zhang¹, Peng Suo¹, Jiaming Chen¹, Kaiwen Sun¹, Yuqing Zou¹, Hong Ma², Xian Lin¹, Xiaona Yan¹, Saifeng Zhang¹, Bo Li³, Guohong Ma¹

Affiliations

¹ Department of Physics, Shanghai University, Shanghai 200444, China.
² School of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
³ Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China.

PMID: 35315678
DOI: 10.1021/acs.jpclett.2c00315

Abstract

By using optical pump and terahertz probe spectroscopy, we have investigated the photocarrier dynamics in PdSe₂ films with different thicknesses. The experimental results reveal that the photocarrier relaxation consists of two components: a fast component of 2.5 ps that shows the layer-thickness independence and a slow component that has typical lifetime of 7.3 ps decreasing with the layer thickness. Interestingly, the relaxation times for both fast and slow components exhibited both pump fluence and temperature independence, which suggests that synergistic interactions between defect trapping and Auger effect dominate the photocarrier dynamics in PdSe₂ films. A model involving a defect-assisted Auger process is proposed, which can reproduce the experimental results well. The fitting results reveal that the layer-dependent lifetime is determined by the defect density rather than carrier occupancy rate after photoexcitation. Our results underscore the interplay between the Auger process and defects in two-dimensional semiconductors.