Specific contact resistances between amorphous oxide semiconductor In–Ga–Zn–O and metallic electrodes

• Published in: Thin solid films 2008-07, Vol.516 (17), p.5899-5902
• Main Authors: Shimura, Yasuhiro, Nomura, Kenji, Yanagi, Hiroshi, Kamiya, Toshio, Hirano, Masahiro, Hosono, Hideo
• Format: Article
• Language: English
• Subjects: Amorphous semiconductor; Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Contact resistance; Contact resistance, contact potential; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in interface structures; Electronics; Exact sciences and technology; Inorganic semiconductor; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Thin film transistor; Transistors
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2007.10.051

Specific contact resistances between an amorphous oxide semiconductor, In–Ga–Zn–O, and various metallic electrodes, Ag, Au, In, Pt, Ti, polycrystalline indium tin oxide (ITO) and amorphous indium zinc oxide (a-IZO), were examined. All the contacts except for Au and Pt showed linear current–voltage characteristics, while Au and Pt did Schottky contacts. Low contact resistances < 10 − 4  Ω cm 2 were obtained for the Ag, In, Ti, ITO and a-IZO contacts, and there is a trend that the contact resistance decreases with decreasing the work function of the metallic electrode. The performances of thin film transistors using ITO and Ti for source and drain contacts were better than that using the Schottky Au contacts. It was also found that the Ti contacts have a large distribution in the contact resistance, suggesting that a higher reproducibility process should be employed when reactive metals are used for an electrical contact to an oxide semiconductor.