In this work, we have successfully demonstrated the junctionless (JL) transistors with two-dimensional-like (2D-like) nano-sheet (NS) material, amorphous indium tungsten oxide (a-IWO), as an active channel layer. The influences of the different gate insulator (GI) materials and the scalings of GI thickness, a-IWO channel thickness, and channel lengths on the a-IWO NS JL transistors (a-IWO NS-JLTs) have been studied for the purposes of low operation voltage (gate voltage ≤2V) and high performance. The 2D-like a-IWO NS-JLTs exhibit low operation voltage, low source/drain (S/D) contact resistance (R C ) and other key electrical characteristics, such as high field-effect mobility (μ FE ), near ideal subthreshold swing (S.S.), and large ON/OFF currents ratio (I ON /I OFF ). The remarkable device characteristics also make the proposed 2D-like a-IWO NS-JLTs promising for system-on-panel (SoP) and vertically stacked (VS) hybrid CMOS applications.

The integration of 4 nm thick amorphous indium tungsten oxide (a-IWO) and a hafnium oxide (HfO2) high-κ gate dielectric has been demonstrated previously as one of promising amorphous oxide semiconductor (AOS) thin-film transistors (TFTs). In this study, the more positive threshold voltage shift (∆VTH) and reduced ION were observed when increasing the oxygen ratio during a-IWO deposition. Through simple material measurements and Technology Computer Aided Design (TCAD) analysis, the distinct correlation between different chemical species and the corresponding bulk and interface density of states (DOS) parameters were systematically deduced, validating the proposed physical mechanisms with a quantum model for a-IWO nanosheet TFT. The effects of oxygen flow on oxygen interstitial (Oi) defects were numerically proved for modulating bulk dopant concentration Nd and interface density of Gaussian acceptor trap NGA at the front channel, significantly dominating the transfer characteristics of a-IWO TFT. Furthermore, based on the studies of density functional theory (DFT) for the correlation between formation energy Ef of Oi defect and Fermi level (EF) position, we propose a numerical methodology for monitoring the possible concentration distribution of Oi as a function of a bias condition for AOS TFTs.