Surface Modification of Solution-Processed ZrO2 Films through Double Coating for Pentacene Thin-Film Transistors

• Published in: Journal of the Korean Physical Society Vol. 72; no. 5; pp. 570 - 576
• Main Authors: Kwon, Jin-Hyuk, Bae, Jin-Hyuk, Lee, Hyeonju, Park, Jaehoon
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Physical Society 01.03.2018; Springer Nature B.V; 한국물리학회
• Subjects: Coating; Contact angle; Dielectric properties; Grain boundaries; Grain size; Mathematical and Computational Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Semiconductor devices; Surface energy; Surface properties; Surface roughness; Theoretical; Thin film transistors; Threshold voltage; Transistors; Zirconium dioxide; Zirconium oxides; 물리학; Solution Process; Transistor; Dielectric; Organic Semiconductor; Zirconium Oxide
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.72.570

We report the modification of surface properties of solution-processed zirconium oxide (ZrO 2 ) dielectric films achieved by using double-coating process. It is proven that the surface properties of the ZrO 2 film are modified through the double-coating process; the surface roughness decreases and the surface energy increases. The present surface modification of the ZrO 2 film contributes to an increase in grain size of the pentacene film, thereby increasing the field-effect mobility and decreasing the threshold voltage of the pentacene thin-film transistors (TFTs) having the ZrO 2 gate dielectric. Herein, the molecular orientation of pentacene film is also studied based on the results of contact angle and X-ray diffraction measurements. Pentacene molecules on the double-coated ZrO 2 film are found to be more tilted than those on the single-coated ZrO 2 film, which is attributed to the surface modification of the ZrO 2 film. However, no significant differences are observed in insulating properties between the single-and the double-coated ZrO 2 dielectric films. Consequently, the characteristic improvements of the pentacene TFTs with the double-coated ZrO 2 gate dielectric film can be understood through the increase in pentacene grain size and the reduction in grain boundary density.