Mechanism of Blue Shift of Optical Band Gap in Aluminum-Doped ZnO Thin Films with Blend Bond

Abstract:

In this paper, aluminum–doped nano-crystalline zinc oxide (ZnO:Al or AZO) thin films were deposited on fused quartz substrate by pulsed laser ablation at various temperatures. The physical phase and surface morphology were characterized by using X-ray diffraction (XRD) and atomic force microscope (AFM), respectively. The variation of the optical band gap (E^g_opt) of the films with the temperature was measured through transmittance in UV-VIS wavelength. The results showed that there was a blue shift of E^g_opt from 3.44 eV to 3.62 eV as the growing temperature decreased from 500°C to 200°C. The value of E^g_opt immediately recurred from 3.30 to 3.35 eV after a thermal annealing of the samples at 700 °C, inclining to a normal value of bulk zinc oxide. The analyses of XRD and AFM testified that the presence of amorphous phase in the AZO films was the main reason for the blue shift of the optical band gap E^g_opt.

• Periodical: Materials Science Forum (Volume 685)
• Pages: 98-104
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.685.98
• Online since: June 2011
• Authors: Ling Shen, Cheng Shen, Jie Yang, Fei Xu, Zhong Quan Ma
• Keywords: Blue Shift, Optical Band Gap, PLD, ZnO Film

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