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ZnO-based transparent thin-film transistors

TitleZnO-based transparent thin-film transistors
Publication TypeJournal Article
Year of Publication2003
AuthorsHoffman, R. L., B. J. Norris, and J. F. Wager
JournalApplied Physics Letters
Date Published2003
Keywordscarrier mobility, II-VI semiconductors, light transmission, persistent currents, photoconductivity, semiconductor device measurement, thin film transistors, wide band gap semiconductors, zinc compounds

Highly transparent ZnO-based thin-film transistors (TFTs) are fabricated with optical transmission (including substrate) of ∼75% in the visible portion of the electromagnetic spectrum. Current–voltage measurements indicate n-channel, enhancement-mode TFT operation with excellent drain current saturation and a drain current on-to-off ratio of ∼10⁷. Threshold voltages and channel mobilities of devices fabricated to date range from ∼10 to 20 V and ∼0.3 to 2.5 cm²/V s, respectively. Exposure to ambient light has little to no observable effect on the drain current. In contrast, exposure to intense ultraviolet radiation results in persistent photoconductivity, associated with the creation of electron-hole pairs by ultraviolet photons with energies greater than the ZnO band gap. Light sensitivity is reduced by decreasing the ZnO channel layer thickness. One attractive application for transparent TFTs involves their use as select-transistors in each pixel of an active-matrix liquid-crystal display.

Short TitleAppl. Phys. Lett.