Chemical and structural analysis of low-temperature excimer-laser annealing in indium-tin oxide sol-gel films

• Published in: Current applied physics Vol. 19; no. 2; pp. 168 - 173
• Main Authors: Kim, Hyuk Jin, Maeng, Min-Jae, Park, J.H., Kang, Min Gyu, Kang, Chong Yun, Park, Yongsup, Chang, Young Jun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2019; 한국물리학회
• Subjects: Excimer-laser annealing (ELA); Indium-tin oxide (ITO); Transmission electron microscopy (TEM); X-ray photoemission spectroscopy (XPS); 물리학; Excimer-laser annealing (ELA); X-ray photoemission spectroscopy (XPS); Transmission electron microscopy (TEM); Indium-tin oxide (ITO)
• ISSN: 1567-1739; 1878-1675; 1567-1739
• DOI: 10.1016/j.cap.2018.12.005

We investigated the influence of excimer-laser annealing (ELA) on the electrical, chemical, and structural properties of indium–tin oxide (ITO) films prepared by a solution process. The ITO film was prepared by the sol-gel method and annealed by excimer-laser pulses with an energy density up to 240 mJ/cm2. Hall measurements showed that the ELA substantially enhanced the electrical properties of the ITO films, including their resistivity, carrier density, and mobility, as increasing the laser energy density. In-depth x-ray photoelectron spectroscopy analysis of the chemical states in the film surface showed that the ELA reduced carbon species and promoted both an oxidation and crystallization. These changes were consistent with results of x-ray diffraction and transmission electron microscopy measurements, where expansions in the microcrystal growth were observed for higher laser energy density. We comprehensively understand that the chemical rearrangement and concomitant crystallization are the main factors for achieving the electrical properties during the ELA. These results suggest the potential of the ELA-treated sol-gel films for providing high-quality ITO films at low temperatures toward the flexible device applications. Excimer laser annealing of indium-tin oxide sol-gel thin films. (a) Schematic diagram of ELA process in ITO thin film, (b) XRD patterns ranged from 50 to 240 mJ/cm2, and cross-sectional TEM images at (c) 100 mJ/cm2, (d) 150 mJ/cm2 and (e) 240 mJ/cm2. The inset shows low-magnification TEM images in the corresponding regions. The scale-bars correspond to 10 nm (50 nm for the insets). [Display omitted] •We investigated the influence of excimer-laser annealing (ELA) on the sol-gel derived indium-tin oxide (ITO) films.•In-depth XPS analysis showed that the ELA reduced carbon species and promoted both an oxidation and crystallization.•We understand that the chemical rearrangement and concomitant crystallization are the main factors during the ELA.