Inducing ferroelectric o-phase in spray-pyrolyzed ZrO2 by La doping for high-performance InGaZnO ferroelectric thin-film transistors

초록

We report the La doping effect in ZrO2 at a substantially lower process temperature of 450 degrees C. The optimum La doping in ZrO2 increases the orthorhombic phase fraction due to the reduction of bulk free and surface energy between orthorhombic phase and monoclinic phase. The 30 nm ZrO2 demonstrates enhanced remnant polarization of 18.4 mu C cm(-2) after 8 % La doping. The inverted staggered InGaZnO thin-film transistors are fabricated with 8 % La:ZrO2 gate oxide, demonstrating memory window tuning from 1.1 to 3.5 V and low subthreshold swing of 43 mV dec(-1) during reverse sweep.

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