Effect on structural, optical and electrical properties of aluminum-doped zinc oxide films using diode laser annealing

• Diode laser system with an 808-nm wavelength used for annealing aluminum-doped zinc oxide (AZO) thin films.
• AZO films characteristics depended on the laser fluence and annealing speed.
• After laser annealing, approximately 90% of transmittance spectra exhibited slight changes.
• The mobility increased as the annealing speed increased when applying laser fluence.
• The optical energy band gap of the annealed AZO films was affected by the carrier concentration.

This study investigated the laser annealing characteristics of aluminum-doped zinc oxide (AZO) films using a diode laser source (808 nm) combined with moving stage with varying parameters, including laser fluence and speed of moving stage in air atmosphere. The commercial AZO thin films were prepared by RF magnetron sputtering on glass substrates. The films characteristics were systematically analyzed using a field emission scanning electron microscope, an atomic force microscope (AFM), an X-ray diffraction (XRD) equipment, an ultraviolet–visible–near-infrared (UV–vis–NIR) spectrophotometer, a four points probe instrument, and a Hall effect measurement system. The experimental results indicate that varying the laser fluence and annealing speed affected the optical, electrical, and structural characteristics of the AZO films. After annealing, approximately 90% of transmittance spectra exhibited slight changes in the visible region. All resistivity values of the laser-annealed AZO films decreased substantially from 4×10−2 Ω cm to 2.8×10−2 Ω cm. The absorption band edge moved toward shorter or longer wavelengths, depending on the annealing laser fluence and annealing speed. The optical energy band gap of the annealed AZO films increased because the carrier concentration of the annealed AZO films increased. The grain size increased in conjunction with the annealing speed. The AFM-derived root mean square (RMS) values decreased as the annealing speed increased, and the corresponding RMS values ranged from 1.4 to 1.9 nm.