Surface morphology and photoelectric properties of fluorine-doped tin oxide thin films irradiated with 532nm nanosecond laser

Abstract

In order to improve the transparency and conductivity of the commercial fluorine-doped tin oxide (FTO) films deposited on glass substrates, a nanosecond pulsed laser with a wavelength of 532 nm was used to irradiate the surfaces of the films. The effects of laser fluence and scanning speed on the surface morphology, photoelectric property and overall quality of the FTO films were investigated. The FTO films which were subjected to lower laser fluences or higher scanning speeds achieved gentle laser annealing effects, resulting in unapparent changes in surface morphology. These changes caused enhancements in optical transmittance and decrease in sheet resistance. The FTO films irradiated with higher laser fluences or lower scanning speeds melted and ablated, causing the optical transmittance and the electrical conductivity of the films to drop significantly. Experimental results indicated that the optimum irradiation fluence and scanning speed for 532 nm nanosecond laser annealing of FTO films were 1.02 J/ cm2 and 10 mm/ s, respectively. The corresponding film had an obvious increase in crystallite size. The RMS roughness, the average optical transmittance in the waveband of 380–780 nm and the figure of merit were increased from 100.5 nm, 75.4% and 5.82×10−3 Ω−1 to 113.0 nm, 82.7% and 17.00×10−3 Ω−1 respectively, while the sheet resistance was reduced from 10.2 Ω/□ to 8.8 Ω/□.