Laser plasma sintering for fabricating indium tin oxide thin films

• ITO thin films are fabricated using novel laser plasma sintering.
• The plasma sintering can enhance the crystallinity and the adhesion performance.
• The grain size and the thickness of the sintered layer can be varied effectively.
• The enhanced sintering is due to combined thermal and mechanical effects.

This paper introduces laser plasma sintering (LPS), and uses it to fabricate dense indium tin oxide (ITO) thin films. LPS uses a nanosecond pulsed laser to generate an airborne laser-induced plasma (LIP) of high temperature and high pressure, which sinters the particles on the substrate. ITO thin films were fabricated by spin-coating ITO nanoparticle (NP) ink onto a substrate then using the LIP to sinter the NPs. The deposited NPs are sintered by the combined effect of the thermal radiation from the LIP and the impact of the shockwave. This LPS process could generate a polycrystalline structure with an average grain size of 280 nm. The electrical resistivity of the film was decreased to ~ 1/1000 of the initial value without losing transparency of the ITO film. The minimum resistivity of 1.6 × 10− 5 Ω·m was obtained significantly reducing the optical transparency of the ITO film. The thickness of the sintered layer and electrical resistivity could be controlled by adjusting the process parameters. LPS also strengthened the adhesion between the sintered film and the substrate significantly, compared with the conventional thermal or laser sintering process. This work suggests that LPS process can be an effective tool to fabricate various thin films with enhanced crystallinity and adhesion characteristics.