Laser Induced Backward Transfer of ultra-thin metal structures

Abstract

Ultra-thin, flexible and stretchable interfaces comprising thin metal films and polymers are attracting increasing interest for applications in sensors and optoelectronics. The transfer of ultra-thin gold films for the digital fabrication of such interfaces was investigated in this study using the Laser-Induced Backward Transfer (LIBT) technique. In particular, the transfer of thin and ultra-thin gold films (60, 10 and 5 nm thick) on Polydimethylosiloxane substrate has been achieved using ps pulses and low laser fluences for controllable material transfer. As the size of the nanograins comprising the Au films decreases, their melting point also decreases, enabling the transfer of intact disk-shaped Au nanostructures at low laser fluence values, with form factors and thickness equal to the pristine films. Moreover, the contribution of the substrate has been clarified: the two substrates (silicon, glass) which were used in this work, have significantly different reflectivity to the selected laser wavelength (532 nm), which can considerably influence the thickness and the quality of the transferred disk. The results presented in this work clearly demonstrate the compatibility of LIBT with ultra-thin metal film/ polymer interfaces and highlight the potential application of this digital process for a variety of optoelectronic applications.