Ultrafast Band-Edge Carrier Dynamics in the Weyl Semiconductor Tellurium Microcrystal

초록

Rod-shaped tellurium microcrystals are promising mid-infrared photonic materials and a prototypical chiral (Weyl) semiconductor, yet intrinsic band-edge relaxation at room temperature is often masked by hot-carrier and photothermal pathways under above-gap excitation. Here, we employ mid-infrared asynchronous and interferometric transient absorption (MIR AI-TA) spectroscopy with frequency-comb pulses centered near the band-edge (380 meV) to directly interrogate two band-edge resonances. The time- and frequency-resolved AI-TA data reveal a fast component characterized by a time constant of 1-2 ps and a long-lived component with a time constant of similar to 50 ps, common to both resonances. A global spectro-temporal model assigns the fast component to phonon-assisted redistribution of valence holes coupled to recovery of pump-induced Peierls distortion, while the slow component corresponds to band-edge electron-hole recombination. These results demonstrate that MIR AI-TA can quantitatively disentangle coupled electronic and structural dynamics in narrow-bandgap semiconductors.

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