Optically transparent thin-film transistors based on 2D multilayer MoS₂ and indium zinc oxide electrodes

We report on optically transparent thin film transistors (TFTs) fabricated using multilayered molybdenum disulfide (MoS₂) as the active channel, indium tin oxide (ITO) for the back-gated electrode and indium zinc oxide (IZO) for the source/drain electrodes, respectively, which showed more than 81% transmittance in the visible wavelength. In spite of a relatively large Schottky barrier between MoS₂ and IZO, the n-type behavior with a field-effect mobility (μ_eff) of 1.4 cm² V^-1 s^-1 was observed in as-fabricated transparent MoS₂ TFT. In order to enhance the performances of transparent MoS₂ TFTs, a picosecond pulsed laser was selectively irradiated onto the contact region of the IZO electrodes. Following laser annealing, μ_eff increased to 4.5 cm² V^-1 s^-1, and the on-off current ratio (I_on/I_off) increased to 10⁴, which were attributed to the reduction of the contact resistance between MoS₂ and IZO.