Sputter-Deposited copper iodide thin film transistors with low Operating voltage.

• Sputter-deposited copper iodide (CuI) p-type thin film transistor(TFT) with a high-κ dielectric, field-effect channel mobility of ~2.1 cm2/Vs, and <5 V low-voltage operation. • Morphology of CuI stabilized by passivation with Al 2 O 3. • I on /I off ratio improves to ~250 after forming gas anneal. This paper reports on a back-gated p-type thin film transistor (TFT) with copper iodide (CuI) as the channel material, a HfO 2 gate dielectric layer, and Al 2 O 3 passivation. The γ-CuI channel was deposited from a CuI target using DC magnetron sputtering at room temperature. Our TFT can be fully shut off by V G = 4 V, with a field-effect channel hole mobility μ h ∼ 1.5–2 cm2 V−1 s−1. An anneal in forming gas was performed twice, once at 200 °C, then at 250 °C to improve gate control, yielding a final I on /I off current ratio of ∼ 250. The anneal served two purposes: to reduce the oxygen acceptor density in the CuI channel and reduce the concentration of interface states between the CuI, Al 2 O 3 passivation, and HfO 2. A model of the device was built in an industrial TCAD simulator, which reproduces the measured characteristics and allows an estimation of interface state densities and channel doping. [ABSTRACT FROM AUTHOR]