Fabrication and characterization of ferroelectric-gate thin-film transistors with an amorphous oxide semiconductor, amorphous In–Ga–Zn–O

Abstract

We fabricated and characterized ferroelectric-gate thin-film transistors (FeTFTs) with an amorphous In-Ga-Zn-O (a-IGZO) channel and an oxide ferroelectric (Bi,La) 4 Ti 3 O 12 (BLT) gate insulator, and examined the fabrication conditions beforehand for realizing ferroelectric hysteresis in their drain current versus gate voltage (I D -V G ) characteristics.First, the optimal annealing conditions for BLT-thin-film formation by the sol-gel method were considered in terms of chemical phenomena and crystallization mechanism.As a result, the leakage current density of the film was decreased by more than two orders of magnitude.Second, sputtering deposition conditions and postdeposition annealing temperatures of a-IGZO thin films were investigated to prepare the a-IGZO channel with good electrical properties.A small charge-injection-type hysteresis width of 0.2 V was obsereved in I D -V G characteristics of a-IGZO/SiO 2 TFTs.Finally, a-IGZO/BLT FeTFTs were fabricated using the above results, and the ferroelectric hysteresis with a width of 0.4 V was observed.