Gate Metals with An Ultra-thin Lithium Fluoride Buffer Layer for Pentacene-Based Organic Thin Film Transistors Applications

• Main Authors: Pei-Pei Hsu, 徐蓓貝
• Other Authors: Yeong-Her Wang
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/72980431101015272481

碩士 === 國立成功大學 === 電機工程學系碩博士班 === 96 === Various metal gate electrodes, including aluminum (Al), hafnium (Hf), tantalum (Ta), titanium (Ti), zirconium (Zr), and other materials such as Indium Tin Oxide (ITO) on glass substrates, were applied to the fabrication of pentacene-based organic thin film transistors. By sputtering deposition on substrates, the metal gate electrodes have poly (4-vinyl phenol) (PVP) as insulator layers over substrate. When compared with the metal gate electrodes with an ultra-thin lithium fluoride films as substrate, this group of electrodes also had an insulator layer that generated effects. Subsequently, the pentacene was primarily selected in p-type organic thin-film transistors. For this reason, the pentacene served as the active layer, while the PVP served as an insulator layer that was easily manufactured for use in spinning and coated in this experiment. It has been found that gate metals such as Hf, Zr, Ta, Al, Ti, and ITO, with an ultra-thin LiF buffer layer for pentacene-based OTFTs, can enhance the drain current, mobility, and on/off ratio significantly. As the results showed, the inserted LiF layer between the dielectric and gate electrode could result in decrease of the surface roughness and increase of grain size of pentacene film. This is attributed in part to improve device performance. Here, we deposit an ultra-thin LiF film between gate electrode and dielectric layer in pentacene-based OTFTs. The on/off current ratio (up to 103) is obviously improved as thickness of the LiF film is approximately 5.0 nm. The metal gate electrodes on the glass substrate with LiF could be successfully integrated into a metal-gated pentacene TFT. Compared with the metals used in the study, the ITO gate electrode, which had the highest work function for OTFTs, showed the best transistor performance.