Laser-based Material Processing and Electronics Fabrication

by Prof. Daeho Lee

Assistant Professor, Mechanical Engineering, Gachon University,Korea

Lasers are effective and capable material-processing tools that offer distinct features and advantages, including choice of wavelength, pulse width and frequency to match the target material properties as well as one-step direct and locally confined structural modification. Moreover, since lasers are controllable with digitized parameters and can be integrated with a CAD (computer-aided design) system they allow a high degree of freedom when the design needs to be changed.

As current technology is pushed to ever smaller dimensions, lasers become a truly enabling solution, reducing thermomechanical damage and facilitating heterogeneous integration of components into functional devices. Laser process can be applied on heat-sensitive flexible substrates since laser provides high peak processing temperature while minimizing thermal damage on the substrate due to localized and rapid heating in conjunction with extremely fast cooling rate. For this reason, lasers are actively used to develop flexible, stretchable and wearable devices nowadays.

In this talk, recent research activities will be presented focused on the laser-assisted material processing and electronics fabrication which will cover, but not limited to, 1) non-vacuum, non-lithographic electrode fabrication by laser direct writing of metal and metal oxide nanoparticle ink, 2) laser-assisted transfer of nanomaterials, 3) laser-assisted nanoimprinting over a large area, 4) localized nanomaterial synthesis and deposition.

Second part of this talk will focus on the laser-assisted one-step patterning of various nanomaterials on flexible substrates and its application to transparent conductors.

In this talk, recent research activities will be presented, focused on the laser-assisted manufacturing and diagnostics technologies for solar applications.

Laser has various characteristics depending on its parameters such as wavelength, pulse duration and frequency, and thus has a diverse range of applications.

 

Laser-assisted localized growth of semiconducting nanostructures is reported. As is the case of conventional crystal growth, localized laser enables three kinds of crystal growth: (1) melt growth (recrystallization) of amorphous silicon nanopillars by pulsed laser; (2) vapor growth (chemical vapor deposition) of germanium nanowires; (3) solution growth (hydrothermal growth) of zinc oxide nanowires. The results not only demonstrate programmable and digital fabrication of laser-assisted crystal growth, but also reveal unusual growth chacracteristics (grain morphologies, growth kinetics). Related to solar applications, it is suggested that these structures can act as epitaxial seeds for growth of coarse grains and as multi-spectral centers for enhanced and engineered light absorption. < back >