title: Flexible metal-oxide devices made by room-temperature photochemical activation of sol-gel films.
abstract: Amorphous metal-oxide semiconductors have emerged as potential replacements for organic and silicon materials in thin-film electronics. The high carrier mobility in the amorphous state, and excellent large-area uniformity, have extended their applications to active-matrix electronics, including displays, sensor arrays and X-ray detectors. Moreover, their solution processability and optical transparency have opened new horizons for low-cost printable and transparent electronics on plastic substrates. But metal-oxide formation by the sol-gel route requires an annealing step at relatively high temperature, which has prevented the incorporation of these materials with the polymer substrates used in high-performance flexible electronics. Here we report a general method for forming high-performance and operationally stable metal-oxide semiconductors at room temperature, by deep-ultraviolet photochemical activation of sol-gel films. Deep-ultraviolet irradiation induces efficient condensation and densification of oxide semiconducting films by photochemical activation at low temperature. This photochemical activation is applicable to numerous metal-oxide semiconductors, and the performance (in terms of transistor mobility and operational stability) of thin-film transistors fabricated by this route compares favourably with that of thin-film transistors based on thermally annealed materials. The field-effect mobilities of the photo-activated metal-oxide semiconductors are as high as 14 and 7 cm(2) V(-1) s(-1) (with an Al(2)O(3) gate insulator) on glass and polymer substrates, respectively; and seven-stage ring oscillators fabricated on polymer substrates operate with an oscillation frequency of more than 340 kHz, corresponding to a propagation delay of less than 210 nanoseconds per stage.
authors.affiliation: Flexible Display Research Center, Korea Electronics Technology Institute, Seongnam 463-816, Korea.
authors.forename: Yong-Hoon
authors.initials: YH
authors.lastname: Kim
authors.forename: Jae-Sang
authors.initials: JS
authors.lastname: Heo
authors.forename: Tae-Hyeong
authors.initials: TH
authors.lastname: Kim
authors.forename: Sungjun
authors.initials: S
authors.lastname: Park
authors.forename: Myung-Han
authors.initials: MH
authors.lastname: Yoon
authors.forename: Jiwan
authors.initials: J
authors.lastname: Kim
authors.forename: Min Suk
authors.initials: MS
authors.lastname: Oh
authors.forename: Gi-Ra
authors.initials: GR
authors.lastname: Yi
authors.forename: Yong-Young
authors.initials: YY
authors.lastname: Noh
authors.forename: Sung Kyu
authors.initials: SK
authors.lastname: Park