Impact ionization dynamics in small band-gap two-dimensional materials from a coherent phonon mechanism

Article

关键词: CHARGE-DENSITY WAVES;    CARRIER MULTIPLICATION;    GENERATION;    EXCITATION;    GRAPHENE;    TISE2;   

DOI  :  10.1103/PhysRevB.100.035431

来源: SCIE

【 摘 要 】

For materials that exhibit dynamic changes in the electronic quasiparticle states after ultrafast optical excitation, it is extremely difficult to unambiguously separate quasiparticle band dynamics and carrier redistribution processes in state-of-the-art photoemission experiments. We study theoretically the interplay of band and carrier dynamics for a model system of a quasi-two-dimensional material with a small band gap and investigate the consequences for electronic distribution curves. Our model system contains photo-induced band-gap narrowing by a coherent phonon mechanism, which mimics the quenching of an insulator phase. We discuss the importance of impact ionization in the ultrafast response and investigate the interplay between carrier and band dynamics. Our model allows us to compare with recent experiments and identify signatures of carrier multiplication in typical electronic distribution curves as measured by time-resolved photoemission spectroscopy. We also investigate the influence of the shape of the bands on the carrier multiplication.

【 授权许可】

Free