Sub-surface laser nanostructuring in stratified metal/dielectric media: a versatile platform towards flexible, durable and large-scale plasmonic writing

Photo-engineered optoelectronic properties of indium tin oxide via reactive laser annealing

Transparent conductive oxides are appealing materials for optoelectronic and plasmonic applications as, amongst other advantages, their properties can be modulated by engineering their defects. Optimisation of this adjustment is, however, a complex design problem. This work examined the modification of the carrier transport properties of sputtered tin-doped indium oxide (ITO) via laser annealing in reactive environments. We relate the optical modifications to the structural, compositional, and electronic properties to elucidate the precise mechanisms behind the reactive laser annealing (ReLA) process. For sufficiently high laser fluence, we reveal an ambient-dependent and purely compositional modulation of the carrier concentration of ITO thin films. Hereby, we demonstrate that ReLA utilises the precise energy delivery of photonic processing to enhance the carrier mobility and finely tune the carrier concentration without significantly affecting the crystal structure. Exploitation of this phenomena may enable one to selectively engineer the optoelectronic properties of ITO, promising an alternative to the exploration of new materials for optoelectronic and photonic applications.

Selective modification of nanoparticle arrays by laser-induced self assembly (MONA-LISA): putting control into bottom-up plasmonic nanostructuring

Nano-structuring of metals is one of the greatest challenges for the future of plasmonic and photonic devices. Such a technological challenge calls for the development of ultra-fast, high-throughput and low-cost fabrication techniques. Laser processing, accounts for the aforementioned properties, representing an unrivalled tool towards the anticipated arrival of modules based in metallic nanostructures, with an extra advantage: the ease of scalability. In the present work we take advantage of the ability to tune the laser wavelength to either match the absorption spectral profile of the metal or to be resonant with the plasma oscillation frequency, and demonstrate the utilization of different optical absorption mechanisms that are size-selective and enable the fabrication of pre-determined patterns of metal nanostructures. Thus, we overcome the greatest challenge of Laser Induced Self Assembly by combining simultaneously large-scale character with atomic-scale precision. The proposed process can serve as a platform that will stimulate further progress towards the engineering of plasmonic devices.