Ultrasonic-Vibration-Assisted Laser Annealing on Photoelectric Properties of FTO Thin Films

doi:10.15541/jim20160695

Abstract

Abstract:

A novel way, i.e. introducing ultrasonic vibration during the laser annealing process, was developed for treating fluorine-doped tin oxide (FTO) transparent conducting thin films. The influences of ultrasonic-vibration-assisted laser annealing on crystal structure, surface morphology and photoelectric properties of the FTO films were investigated. The experimental results indicated that application of ultrasonic vibration during laser annealing caused the films to move up and down and thus brought about a continuous change in laser focusing state, ensuring the films to be in the optimum location to undergo laser annealing. Meanwhile, it could enable the particles in the laser-molten zone on the film surfaces to be dispersed through vibration, thus restraining the agglomeration of the particles and enhancing the uniformity and compactness of the films. As a result, photoelectric properties of the FTO films were effectively improved. It was found that the FTO film obtained by using a vibration power of 300 W was more uniform, compact and smooth, thereby yielding the optimal photoelectric properties with an average optical transmittance of 84.7% in the waveband range of 400~800 nm and a sheet resistance of 9.0 Ω/□.

Key words: fluorine-doped tin oxide (FTO), ultrasonic vibration, laser annealing, photoelectric properties

CLC Number:

REN Nai-Fei, CAO Hai-Di, HUANG Li-Jing, LI Bao-Jia, ZU Wei. Ultrasonic-Vibration-Assisted Laser Annealing on Photoelectric Properties of FTO Thin Films[J]. Journal of Inorganic Materials, 2017, 32(10): 1083-1088.

Figures/Tables 9

Fig. 1 Schematic diagram of ultrasonic-vibration-assisted laser annealing treatment equipment

Fig. 2 XRD patterns of the untreated FTO film sample and the FTO film samples obtained by ultrasonic-vibration-assisted laser annealing using different vibration powers

Table 1 Grain sizes (D) and surface RMS roughnesses of the untreated FTO film sample and the FTO film samples obtained by ultrasonic-vibration-assisted laser annealing using different vibration powers

Power/W	D/nm	RMS/nm
Untreated	22.5	37.6
0	27.3	48.7
100	26.7	29.3
200	25.2	20.5
300	23.9	14.2
400	22.9	26.3
500	21.6	35.8

Fig. 3 SEM (a) and AFM (b) images of untreated FTO film sample

Fig. 4 SEM images of the FTO film samples obtained by ultrasonic-vibration-assisted laser annealing using different vibration powers(a) 0 W; (b) 100 W; (c) 200 W; (d) 300 W; (e) 400 W; (f) 500 W

Fig. 5 AFM image of the 300-W sample

Fig. 6 Schematic diagram for evolution of particle distribution on the FTO film surface during ultrasonic-vibration-assisted laser annealing process

Fig. 7 Transmittance spectra of the untreated FTO film sample and the FTO film samples obtained by ultrasonic-vibration- assisted laser annealing using different vibration powers

Table 2 Average transmittances (Tav) and sheet resistances (Rsh) of the FTO film samples obtained by ultrasonic-vibration-assisted laser annealing using different vibration powers

Power/W	T_av (400~800 nm)/%	R_sh/(Ω·□^-1)
0	81.0	9.4
100	81.9	9.3
200	82.8	9.2
300	84.7	9.0
400	82.7	9.1
500	81.6	9.2

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