title: Impact of the cation composition on the electrical performance of solution-processed zinc tin oxide thin-film transistors.
abstract: This study examined the structural, chemical, and electrical properties of solution-processed (Zn,Sn)O3 (ZTO) films with various Sn/[Zn+Sn] ratios for potential applications to large-area flat panel displays. ZTO films with a Zn-rich composition had a polycrystalline wurtzite structure. On the other hand, the Sn-rich ZTO films exhibited a rutile structure, where the Zn atom was speculated to replace the Sn site, thereby acting as an acceptor. In the intermediate composition regions (Sn/[Zn+Sn] ratio from 0.28 to 0.48), the ZTO films had an amorphous structure, even after annealing at 450 °C. The electrical transport properties and photobias stability of ZTO thin film transistors (TFTs) were also examined according to the Sn/[Zn+Sn] ratio. The optimal transport property of ZTO TFT was observed for the device with an amorphous structure at a Sn/[Zn+Sn] ratio of 0.48. The mobility, threshold voltage, subthreshold swing, and on/off current ratio were 4.3 cm(2)/(V s), 0 V, 0.4 V/decade, and 4.1 × 10(7), respectively. In contrast, the device performance for the ZTO TFTs with either a higher or lower Sn concentration suffered from low mobility and a high off-state current, respectively. The photoelectrical stress measurements showed that the photobias stability of the ZTO TFTs was improved substantially when the ZTO semiconducting films had a lower oxygen vacancy concentration and an amorphous structure. The relevant rationale is discussed based on the phototransition and subsequent migration mechanism from neutral to positively charged oxygen vacancies.
authors.affiliation: Department of Materials Science and Engineering, and Inter-university Semiconductor Research Center, Seoul National University , Seoul 151-742, Republic of Korea.
authors.forename: Yoon Jang
authors.initials: YJ
authors.lastname: Kim
authors.forename: Seungha
authors.initials: S
authors.lastname: Oh
authors.forename: Bong Seob
authors.initials: BS
authors.lastname: Yang
authors.forename: Sang Jin
authors.initials: SJ
authors.lastname: Han
authors.forename: Hong Woo
authors.initials: HW
authors.lastname: Lee
authors.forename: Hyuk Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jae Kyeong
authors.initials: JK
authors.lastname: Jeong
authors.forename: Cheol Seong
authors.initials: CS
authors.lastname: Hwang
authors.forename: Hyeong Joon
authors.initials: HJ
authors.lastname: Kim