30-nm-channel-length c-axis aligned crystalline In-Ga-Zn-O transistors with low off-state leakage current and steep subthreshold characteristics

We report the world's smallest field effect transistors (FETs) with channel lengths of 32 nm including c-axis aligned crystalline (CAAC) In-Ga-Zn-O as their active layers, which achieve low off-state leakage currents. Furthermore, these FETs exhibit excellent subthreshold swing values despite having thick gate insulating film. The FET operation has been achieved owing to the 3D gate structure with a thin active layer, due to the FETs being accumulation-type FETs with intrinsic channels, and due to the dielectric anisotropy of the CAAC crystal structure.