A Coplanar Crystalline InGaO Thin Film Transistor with SiO2 Gate Insulator on ZrO2 Ferroelectric Layer: A New Ferroelectric TFT Structure.

Ferroelectric transistors with a large memory window (MW) and operational stability have been of increasing interest recently. In this study, a ferroelectric thin‐film transistor (FE‐TFT) with a novel metal‐insulator‐semiconductor‐ferroelectric (MISF) structure is proposed. With the ferroelectric layer located under the semiconductor, the TFT process can be similar to a conventional coplanar structure with a SiO2 gate insulator (GI). In this work, both FE and active semiconductors are deposited by spray pyrolysis which is beneficial for large‐area and low‐cost manufacturing. The FE ZrO2 by spray pyrolysis has a nanocrystalline phase, and the semiconductor InGaO shows a polycrystalline structure. The TFT exhibits a MW of 5.6 V with an operating voltage range of −10–10 V. The device shows a low leakage current of 10−12 A, and thus the on/off ratio is >107 at VDS = 1.0 V. The device shows stable performance with increasing temperatures up to 80 °C. The endurance of the device is 5000 cycles at 0.1 Hz pulse with a negligible variation of MW less than 0.1 V, indicating excellent operational stability. [ABSTRACT FROM AUTHOR]