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.

Nonvolatile Ferroelectric P(VDF-TrFE) Memory Transistors Based on Inkjet-Printed Organic Semiconductor

“…The initial on/off-state current ratio is found to be higher than 10 2 , and a ratio of more than 10 remains after the lapsed time of 10 3 seconds. The retention time value is considerably smaller than previously reported [4], [7]. Although the reason for this difference in value is not clear at present, in general, the retention characteristics of programmed currents for this type of memory transistor are very sensitive to the read-out conditions of V G .…”

“…Moreover, the width of the memory window increases in an almost symmetrical manner toward both positive and negative In these series of measurements, the memory windows are slightly increased toward only the negative direction, whereas the V on remains the same [4]. Consequently, we can control and design the operation voltage and corresponding memory behaviors by using the operation schemes shown in Figs.…”

“…The overall process temperature should be below 200°C [4]. Polymeric ferroelectric thin films can offer an attractive solution to this problem because their crystallization temperatures are much lower than those of oxide ferroelectrics.…”

An upconverted photonic nonvolatile memory

“…We further demonstrate the hybrid memory on flexible PEN substrate. Until now, there are very few reports of hybrid flash memory devices, most of which use rigid substrate 53,54 or large program/erase voltage 55 . Here we use the atomic layer deposition method to fabricate the aluminium oxide (Al 2 O 3 ) dielectric layer at low temperature, demonstrating good reproducibility and sufficient uniformity with high device yields.…”

Nanoionics-Based Three-Terminal Synaptic Device Using Zinc Oxide

“…36 TCO devices employing a ferroelectric gate insulator have also been reported to show EPSC behaviour. 28,37 The (fig 1i). It is revealed here that the anomalous counter-clockwise hysteresis arises from the positive gate sweep and application of a negative gate bias restores the charge separation to its initial state.…”