Enhancement of the Ultraviolet Photoresponsivity of Al-doped ZnO Thin Films Prepared by using the Sol-gel Spin-coating Method

• Published in: Journal of the Korean Physical Society 2018, 72(5), , pp.610-614
• Main Authors: Lee, Wookbin, Leem, Jae-Young
• Format: Article
• Language: English
• Subjects: Absorbance; Diffraction patterns; Doping; Doppler effect; Electron microscopy; Emission; Grain size; Lattice parameters; Mathematical and Computational Physics; Optical properties; Particle and Nuclear Physics; Photoluminescence; Physics; Physics and Astronomy; Red shift; Silicon substrates; Sol-gel processes; Spin coating; Theoretical; Thin films; Zinc oxide; 물리학
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.72.610

We report the structural, morphological, optical, and ultraviolet (UV) photoresponse properties of Al-doped ZnO (AZO) thin films prepared on silicon substrates with different Al doping concentrations by using the sol-gel spin-coating method. An analysis of the X-ray diffraction patterns of the AZO thin films revealed that the average grain size decreased and the c -axis lattice constant increased with Al content. The field-emission scanning electron microscopy images showed that with Al doping, the grain size decreased, but the film density increased with increasing Al doping concentration from 0% to 3%. These results indicate that the surface area of the film increased with increasing Al doping. The absorbance spectra revealed that the UV absorbance of the AZO thin films increased with increasing Al doping concentration and that the absorption onset shifted towards lower energies. The photoluminescence spectra revealed that with increasing Al doping, the intensity of the visible emission greatly decreased and the visible emission peak shifted forward lower energy (a red shift). The UV sensor based on the AZO thin films exhibited a higher responsivity than that based on the undoped ZnO thin film. Therefore, this study provides a facile method for improving the photoresponsivity of UV sensors.