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Electrical and optical properties of Nb-doped TiO 2 films deposited by dc magnetron sputtering using slightly reduced Nb-doped TiO 2 − x ceramic targets J. Vac. Sci. Technol. A 28, 851 (2010); 10.1116/1.3358153 Structure, optical, and electrical properties of indium tin oxide thin films prepared by sputtering at room temperature and annealed in air or nitrogen Transparent conductive In 2 O 3 -SnO 2 films were deposited by dc magnetron sputtering on unheated glass substrates using high-density ceramic targets with various SnO 2 concentrations ͑0-100 wt. %͒. These films were subsequently postannealed in various atmospheres ͓air, Ar ͑100%͒ or Ar͑97% ͒ +H 2 ͑3%͔͒ for 1 h at 200°C. All the as-deposited films were amorphous by X-ray diffraction ͑XRD͒. After the postannealing, XRD profiles of the films deposited using the targets in the range of 0-20 wt. % SnO 2 showed bixbyte In 2 O 3 polycrystalline structure, whereas all the films deposited using the targets with 44.5 wt. % SnO 2 and 100 wt. % ͑pure SnO 2 ͒ were amorphous. Resistivity of the films deposited using the targets in the range of 0-20 wt. % SnO 2 went from about 4.0 ϫ 10 −4 to 2.0ϫ 10 −4 ⍀ · cm by the postannealing under all atmospheres due to increased carrier density. This implies an increase in the number of the substitutional Sn 4+ at In 3+ sites during crystallization. The work function of the postannealed films was inversely proportional to the two-thirds power of carrier density.

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We fabricated a field-effect transistor (FET) with a gate length of 21 nm whose channel material is a c-axis-aligned crystalline In-Ga-Zn oxide (CAAC-IGZO). A CAAC-IGZO FET with a gate length of 21 nm has an extremely low off-state leakage current, a practical driving capability, and tolerance against high temperatures. CAAC-IGZO FETs enable low-power integrated circuits, such as logic and memory in high-temperature environments. Performance estimation of a memory cell using the CAAC-IGZO FET with a gate length of 21 nm revealed that a write time of less than 1 ns and a data retention time of more than 1 h would be possible at 85 • C.INDEX TERMS C-axis-aligned crystalline In-Ga-Zn oxide (CAAC-IGZO), leakage current, nonvolatile memory, random access memory. II. BASIC CHARACTERISTICS OF C-AXIS-ALIGNED CRYSTALLINE IN-GA-ZN OXIDE FET

In a C‐axis aligned crystal (CAAC) IGZO TFT, contact between a CAAC‐IGZO film and source and drain electrode was good. In this study, we recognized the existence of n‐type IGZO layer serving as contact layer by a novel experimental method where a depth profile of the sheet resistance.