Femtosecond laser ablation of indium tin-oxide narrow grooves for thin film solar cells

Abstract

Finding ways to scribe indium-tin oxide (ITO) coating plays an important role in the fabrication and assembly of thin film solar cells. Using a femtosecond (fs) laser, we selectively removed the ITO thin films with thickness 120–160nm on glass substrates. In particular, we studied the effect of laser pulse duration, laser fluence and laser scanning speed on the ablation of ITO. The single pulse ablation thresholds at various pulse durations were determined to ablate ITO thin films. Clean removal of the ITO layer was observed when the laser fluence was above the threshold of 0.30J/cm2. Furthermore, the morphologies and microstructure of fabricated grooves were characterized using a scanning electron microscope and KLA Tencor P-16 Profiler. A groove width down to 3μm with 10nm groove ridge can be achieved by the ablation of femtosecond laser pulses with 220nJ of energy. The femtosecond laser therefore provides a unique scheme to ablate the indium tin-oxide layer for the fabrication of thin film solar cells.