title: In/Ga-free, inkjet-printed charge transfer doping for solution-processed ZnO.
abstract: An In/Ga-free doping method of zinc oxide (ZnO) is demonstrated utilizing a printable charge transfer doping layer (CTDL) based on (3-aminopropyl)triethoxysilane (APS) molecules. The self-assembled APS molecules placed on top of ZnO thin films lead to n-type doping of ZnO and filling shallow electron traps, due to the strong electron-donating characteristics of the amine group in APS molecules. The CTDL doping can tune the threshold voltage and the mobility of the ZnO thin-film transistors (TFTs) as one varies the grafting density of the APS molecules and the thickness of the underneath ZnO thin films. From an optimized condition, high-performance ZnO TFTs can be achieved that exhibit an electron mobility of 4.2 cm(2)/(V s), a threshold voltage of 10.5 V, and an on/off current ratio larger than 10(7). More importantly, the method is applicable to simple inkjet processes, which lead to produce high-performance depletion load ZnO inverters through selective deposition of CTDL on ZnO thin films.
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University , Suwon, 440-746, Korea.
authors.forename: Seong Hun
authors.initials: SH
authors.lastname: Yu
authors.forename: Beom Joon
authors.initials: BJ
authors.lastname: Kim
authors.forename: Moon Sung
authors.initials: MS
authors.lastname: Kang
authors.forename: Se Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Jong Hun
authors.initials: JH
authors.lastname: Han
authors.forename: Jun Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Jeong Ho
authors.initials: JH
authors.lastname: Cho