[16a-F203-1~11] 17.3 Layered materials

[16a-F203-10] Fabrication of thin film transistors using solution processed MoS₂ directly deposited on high-k oxide film for thin film transistor

〇(DC)Joonam Kim¹, Kennichi Haga¹, Eisuke Tokumitsu¹ (1.JAIST)

Keywords:MoS2, semiconductor, high-k

In this work, TFTs with the chemical solution processed MoS₂ channel which was directly deposited on the high-k oxide film was investigated. The (NH₄)₂MoS₄ powder was dissolved in N-methyl-2-pyrrolidone (NMP) for MoS₂ precursor solution. To investigate the appropriate gate oxide for spin-coating of MoS₂, we first examined coating property of the source solution on various kinds of dielectric oxide films as well as thermal stability at 1000ºC with sulfur atmosphere, and selected Nb-doped ZrO₂(NZO). The 0.05 mol/kg MoS₂ solution were spin-coated on NZO/Si substrates and annealed by a two-step annealing process, where the first annealing is performed at 450 ºC in H₂/Ar (5:95) atmosphere for 20 min and the second annealing at 1000 ºC in Ar atmosphere with S vapor for 20 min. It is confirmed by Raman scattering spectroscopy that the MoS₂ layers were grown on the NZO film. In addition, although the NZO film shows rough surface, the conformal growth of a MoS₂ layered structure on the curved surface of the oxide film was confirmed by transmission electron microscope. Normal n-type transistor operation was observed. The on/off drain current ratio was 4.5x10⁴ and the estimated field effect mobility was 0.32~0.71 cm²/Vs.