Bonding of single-layered Cu2O nanospheres on Cu substrates in irradiating near-infrared femtosecond laser pulses

Abstract

Abstract We investigated the bonding mechanism of single-layered Cu2O nanospheres (NSs) on Cu thin films. When near-infrared femtosecond laser pulses were focused and irradiated on the Cu2O NS films containing the NSs and reducing agents on Cu thin film-coated Si substrates, single-layered NSs were bonded just above the substrates after rinsing the non-bonded NSs. The minimum pulse energy for the single bonding on the Cu thin film-coated Si substrates was smaller than that on Si substrates. The electromagnetic enhancement was calculated between the Cu2O NSs and Cu thin films by simulating the finite element method. The enhancement was estimated using a transverse mode of the linear polarization of the incident femtosecond laser pulses. The experimental and simulation results indicated that the single-layered NSs were bonded on the Cu thin films by femtosecond laser pulse-induced local heating and melting due to the localized plasmon enhancement between the Cu2O NSs and substrates.