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

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.

Ultrafast Carrier Dynamics in 2D NbTe2 Films: Implications for Photonic and Optoelectronic Devices

“…Also, τ 2 (several hundreds of picoseconds) in our measurements is much shorter than the radiative recombination time. , Other possible mechanisms are Auger and phonon-assisted electron–hole recombination. Auger recombination is a three-body process that involves the recombination of an electron and a hole as well as an energy transfer to a third charge carrier, , while in phonon-assisted recombination, the electron and hole recombine with the assistance of electron–phonon scattering between the electron and hole pockets. This process exists commonly in semimetals, such as bismuth, WTe 2 , TiTe 2 , and PdTe 2 .…”

Ultrafast carrier dynamics in GeSn thin film based on time-resolved terahertz spectroscopy

“…In order to apply this ma-terial, it is necessary to understand the interaction between infrared photons and the material, especially the carrier relaxation behavior after photoexcitation and the electrical properties of the generated carriers. Therefore, we perform timeresolved terahertz spectroscopy (TRTS) [17][18][19] to measure the epitaxial grown GeSn thin films.…”

Ultrafast Photocarrier Dynamics in Vertically Aligned SnS2 Nanoflakes Probing with Transient Terahertz Spectroscopy

“…2D materials, such as graphene, black phosphorus (BP) and transition metal dichalcogenides (TMDs) consist of single layer held together by weak van der Waals interactions, which have been paid extensive attention due to their unique mechanical, electric and optical properties [ 1 , 2 , 3 , 4 ]. The 2D materials also provide a playground for testing new concept in physics and are building block for designing and developing novel devices with desired functionality [ 5 , 6 , 7 ].…”

“…Considering the low photon energy of THz radiation (1 THz~4.1 meV), optical pump and THz probe spectroscopy (OPTP) can directly sample the dynamics of free carriers and probe the photoconductive response of materials in a noncontact way. Transient THz photoconductivity (PC) spectroscopy has been demonstrated as useful for investigating photocarrier dynamics in graphene, semiconducting and semimetallic TMDs, and other materials [ 4 , 5 , 6 , 10 ], which allows us to probe the charge transfer and dynamical relaxation of the desired system [ 28 ].…”