Ferroelectric-Gate Thin-Film Transistor Fabricated by Total Solution Deposition Process

Abstract

We have fabricated inorganic ferroelectric-gate thin-film transistors (FGTs) using only a chemical solution deposition (CSD) process. All layers, including the LaNiO3 (LNO) gate electrode, Pb(Zr,Ti)O3 (PZT) ferroelectric-gate insulator, indium–tin-oxide (ITO) source/drain electrodes, and ITO channel, were formed on a SrTiO3 (STO) substrate by the CSD process. We obtained a local epitaxially grown PZT/LNO perovskite heterostructure with good crystalline quality and no interfacial layer. The fabricated FGT exhibited typical n-channel transistor operation, with a counterclockwise hysteresis loop due to the ferroelectric nature of the PZT-gate insulator, and also exhibited good drain current saturation in output characteristics. These properties are equivalent to or better than those obtained with FGTs fabricated by means of conventional vacuum processes. The obtained on/off current ratio, memory window, and subthreshold voltage swing were about 106, 2.5 V, and 357 mV/decade, respectively.