Photo-assisted epitaxial growth from nanoparticles to enhance multi-materialization for advanced surface functionalization

To meet the requirements of freeform objects, a wide range of highly designable resin-based materials has been created, highlighting the need for low-temperature ceramic deposition methods for surface functionalization. Photo-assisted chemical solution deposition (PCSD), an efficient technique for low-temperature ceramic growth, is used to fabricate thin films via photochemical and photothermal effects. The hybrid-solution-incorporated PCSD (HS-PCSD), in which a hybrid-solution comprising metal-organic compounds and nanoparticles is used in PCSD, has attracted considerable interest as it enables deposition at reduced temperatures and accelerated rates. However, the crystal growth processes in the HS-PCSD remain underexplored, which hinders the design of films using this method. In this study, we quantitatively evaluated the photocrystallization of ceramic thin films that were fabricated under various HS-PCSD conditions. We determined that the laser intensity at the reaction interface must exceed a threshold for epitaxial growth through dangling bond photoactivation and photothermal atomic migration to compete with crystal nucleation growth. We also identified that the particle growth during photocrystallization occurred because of amorphous-phase crystallization and not grain boundary migration. Through these quantitative analyses, we obtained insights into ways to achieve true multi-materialization with desirable physical properties in HS-PCSD.