Ultrafast Dynamics of Defect-Assisted Auger Process in PdSe2Films:Synergistic Interaction between Defect Trapping and Auger Effect

By using optical pump and terahertz probe spectroscopy, we have investigated thephotocarrier dynamics in PdSe2films with different thicknesses. The experimental results revealthat the photocarrier relaxation consists of two components: a fast component of 2.5 ps thatshows the layer-thickness independence and a slow component that has typical lifetime of 7.3 psdecreasing with the layer thickness. Interestingly, the relaxation times for both fast and slowcomponents exhibited both pumpfluence and temperature independence, which suggests thatsynergistic interactions between defect trapping and Auger effect dominate the photocarrierdynamics in PdSe2films. A model involving a defect-assisted Auger process is proposed, whichcan reproduce the experimental results well. Thefitting results reveal that the layer-dependentlifetime is determined by the defect density rather than carrier occupancy rate afterphotoexcitation. Our results underscore the interplay between the Auger process and defectsin two-dimensional semiconductors.

Automated summary

We investigated the photocarrier dynamics in PdSe2 films with different thicknesses using optical pump and terahertz probe spectroscopy. Our experimental results showed the presence of two components in the photocarrier relaxation process, a fast component and a slow component. The interaction between defect trapping and Auger effect was found to dominate the photocarrier dynamics in PdSe2 films. We proposed a model involving defect-assisted Auger process which reproduced the experimental results well.