Ultrafast Carrier and Lattice Dynamics in Plasmonic Nanocrystalline Copper Sulfide Films. Issue 3 (21st January 2021)

• Record Type: Journal Article
• Authors: Bykov, Anton Yu.; Shukla, Amaresh; van Schilfgaarde, Mark; Green, Mark A.; Zayats, Anatoly V.
• Is Part Of: Laser & photonics reviews. Volume 15:Issue 3(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-01-21
• Subjects: coherent optical phonons -- copper sulfide -- nonequilibirium processes -- plasmonics -- ultrafast hot‐carrier dynamics; Lasers -- Periodicals; Photonics -- Periodicals; Lasers -- Périodiques; Photonique -- Périodiques; 621.36
• DOI: 10.1002/lpor.202000346
• Languages: English
• ISSNs: 1863-8880

Abstract

Abstract: Excited carrier dynamics in plasmonic nanostructures determines many important optical properties such as nonlinear optical response and photocatalytic activity. Here it is shown that mesoscopic plasmonic covellite nanocrystals with low free‐carrier concentration exhibit a much faster carrier relaxation than in traditional plasmonic materials. A nonequilibrium hot‐carrier population thermalizes within first 20 fs after photoexcitation. A decreased thermalization time in nanocrystals compared to a bulk covellite is consistent with the reduced Coulomb screening in ultrathin films. The subsequent relaxation of thermalized, equilibrium electron gas is faster than in traditional plasmonic metals due to the lower carrier concentration and agrees well with that in a bulk covellite showing no evidence of quantum confinement or hot‐hole trapping at the surface states. The excitation of coherent optical phonon modes in a covellite is also demonstrated, revealing coherent lattice dynamics in plasmonic materials, which until now was mainly limited to dielectrics, semiconductors, and semimetals. These findings show advantages of this new mesoscopic plasmonic material for active control of optical processes. Abstract : Excited carrier dynamics in plasmonic nanostructures determines many important optical properties. Here a comprehensive study of equilibrium and non‐equilibrium hot carrier dynamics in mesoscopic plasmonic covellite nanocrystals is reported, which exhibit a much faster carrier relaxation than traditional plasmonic materials. Furthermore, coherent lattice dynamics in plasmonic materials is demonstrated and analyzed.