title: Absorption properties of metal-semiconductor hybrid nanoparticles.
abstract: The optical response of hybrid metal-semiconductor nanoparticles exhibits different behaviors due to the proximity between the disparate materials. For some hybrid systems, such as CdS-Au matchstick-shaped hybrids, the particles essentially retain the optical properties of their original components, with minor changes. Other systems, such as CdSe-Au dumbbell-shaped nanoparticles, exhibit significant change in the optical properties due to strong coupling between the two materials. Here, we study the absorption of these hybrids by comparing experimental results with simulations using the discrete dipole approximation method (DDA) employing dielectric functions of the bare components as inputs. For CdS-Au nanoparticles, the DDA simulation provides insights on the gold tip shape and its interface with the semiconductor, information that is difficult to acquire by experimental means alone. Furthermore, the qualitative agreement between DDA simulations and experimental data for CdS-Au implies that most effects influencing the absorption of this hybrid system are well described by local dielectric functions obtained separately for bare gold and CdS nanoparticles. For dumbbell shaped CdSe-Au, we find a shortcoming of the electrodynamic model, as it does not predict the "washing out" of the optical features of the semiconductor and the metal observed experimentally. The difference between experiment and theory is ascribed to strong interaction of the metal and semiconductor excitations, which spectrally overlap in the CdSe case. The present study exemplifies the employment of theoretical approaches used to describe the optical properties of semiconductors and metal nanoparticles, to achieve better understanding of the behavior of metal-semiconductor hybrid nanoparticles.
authors.affiliation: Institute of Chemistry and the Center for Nanoscience & Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Ehud
authors.initials: E
authors.lastname: Shaviv
authors.forename: Olaf
authors.initials: O
authors.lastname: Schubert
authors.forename: Marcelo
authors.initials: M
authors.lastname: Alves-Santos
authors.forename: Guido
authors.initials: G
authors.lastname: Goldoni
authors.forename: Rosa
authors.initials: R
authors.lastname: Di Felice
authors.forename: Fabrice
authors.initials: F
authors.lastname: Vallée
authors.forename: Natalia
authors.initials: N
authors.lastname: Del Fatti
authors.forename: Uri
authors.initials: U
authors.lastname: Banin
authors.forename: Carsten
authors.initials: C
authors.lastname: Sönnichsen
mesh_terms: D000042:Absorption; D019187:Cadmium Compounds / Q000737:chemistry; D003198:Computer Simulation; D004563:Electrochemistry / Q000379:methods; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission / Q000379:methods; D036103:Nanotechnology / Q000379:methods*; D055095:Optics and Photonics / Q000379:methods; D045663:Quantum Dots; D012666:Semiconductors; D013440:Sulfides / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D008670:Metals; D013440:Sulfides; C034939:cadmium sulfide; D006046:Gold