title: Dual active layer a-IGZO TFT via homogeneous conductive layer formation by photochemical H-doping.
abstract: In this study, InGaZnO (IGZO) thin film transistors (TFTs) with a dual active layer (DAL) structure are fabricated by inserting a homogeneous embedded conductive layer (HECL) in an amorphous IGZO (a-IGZO) channel with the aim of enhancing the electrical characteristics of conventional bottom-gate-structure TFTs. A highly conductive HECL (carrier concentration at 1.6 × 10(13) cm(-2), resistivity at 4.6 × 10(-3) Ω∙cm, and Hall mobility at 14.6 cm(2)/Vs at room temperature) is fabricated using photochemical H-doping by irradiating UV light on an a-IGZO film. The electrical properties of the fabricated DAL TFTs are evaluated by varying the HECL length. The results reveal that carrier mobility increased proportionally with the HECL length. Further, a DAL TFT with a 60-μm-long HECL embedded in an 80-μm-long channel exhibits comprehensive and outstanding improvements in its electrical properties: a saturation mobility of 60.2 cm(2)/Vs, threshold voltage of 2.7 V, and subthreshold slope of 0.25 V/decade against the initial values of 19.9 cm(2)/Vs, 4.7 V, and 0.45 V/decade, respectively, for a TFT without HECL. This result confirms that the photochemically H-doped HECL significantly improves the electrical properties of DAL IGZO TFTs.
authors.affiliation: Department of Materials Science and Engineering, 222 Wangsimni-Ro, Seongdong-Gu, Hanyang University, Seoul 133-791, Republic of Korea.
authors.forename: Seung-Ki
authors.initials: SK
authors.lastname: Jeong
authors.affiliation: Department of Materials Science and Engineering, 222 Wangsimni-Ro, Seongdong-Gu, Hanyang University, Seoul 133-791, Republic of Korea.
authors.forename: Myeong-Ho
authors.initials: MH
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering and Department of Energy System Research, Ajou University, 206 Worldcup-ro, Yeongtong-Gu, Suwon 443-739, Republic of Korea.
authors.forename: Sang-Yeon
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Department of Materials Science and Engineering and Department of Energy System Research, Ajou University, 206 Worldcup-ro, Yeongtong-Gu, Suwon 443-739, Republic of Korea.
authors.forename: Hyungtak
authors.initials: H
authors.lastname: Seo
authors.affiliation: Department of Materials Science and Engineering, 222 Wangsimni-Ro, Seongdong-Gu, Hanyang University, Seoul 133-791, Republic of Korea.
authors.forename: Duck-Kyun
authors.initials: DK
authors.lastname: Choi
keywords: Dual active layers; Hydrogen donor; Photochemical doping; TFT; UV irradiation; a-IGZO