Fully Transparent Non-volatile Memory Thin-Film Transistors Using an Organic Ferroelectric and Oxide Semiconductor Below 200 °C

Abstract

A fully transparent non-volatile memory thin-film transistor (T-MTFT) is demonstrated. The gate stack is composed of organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] and oxide semiconducting Al-Zn-Sn-O (AZTO) layers, in which thin Al₂O₃ is introduced between two layers. All the fabrication processes are performed below 200 °C on the glass substrate. The transmittance of the fabricated device was more than 90% at the wavelength of 550 nm. The memory window obtained in the T-MTFT was 7.5 V with a gate voltage sweep of −10 to 10 V, and it was still 1.8 V even with a lower voltage sweep of −6 to 6 V. The field-effect mobility, subthreshold swing, on/off ratio, and gate leakage currents were obtained to be 32.2 cm² V⁻¹ s⁻¹, 0.45 V decade⁻¹, 10⁸, and 10⁻¹³ A, respectively. All these characteristics correspond to the best performances among all types of non-volatile memory transistors reported so far, although the programming speed and retention time should be more improved.