Atomic-Layer-Deposition of Indium Oxide Nano-films for Thin-Film Transistors Article Swipe
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· 2018
· Open Access
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· DOI: https://doi.org/10.1186/s11671-017-2414-0
· OA: W2784019474
Atomic-layer-deposition (ALD) of In<sub>2</sub>O<sub>3</sub> nano-films has been investigated using cyclopentadienyl indium (InCp) and hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) as precursors. The In<sub>2</sub>O<sub>3</sub> films can be deposited preferentially at relatively low temperatures of 160-200 °C, exhibiting a stable growth rate of 1.4-1.5 Å/cycle. The surface roughness of the deposited film increases gradually with deposition temperature, which is attributed to the enhanced crystallization of the film at a higher deposition temperature. As the deposition temperature increases from 150 to 200 °C, the optical band gap (E<sub>g</sub>) of the deposited film rises from 3.42 to 3.75 eV. In addition, with the increase of deposition temperature, the atomic ratio of In to O in the as-deposited film gradually shifts towards that in the stoichiometric In<sub>2</sub>O<sub>3</sub>, and the carbon content also reduces by degrees. For 200 °C deposition temperature, the deposited film exhibits an In:O ratio of 1:1.36 and no carbon incorporation. Further, high-performance In<sub>2</sub>O<sub>3</sub> thin-film transistors with an Al<sub>2</sub>O<sub>3</sub> gate dielectric were achieved by post-annealing in air at 300 °C for appropriate time, demonstrating a field-effect mobility of 7.8 cm<sup>2</sup>/V⋅s, a subthreshold swing of 0.32 V/dec, and an on/off current ratio of 10<sup>7</sup>. This was ascribed to passivation of oxygen vacancies in the device channel.
