Excellent low-voltage operating flexible ferroelectric organic transistor nonvolatile memory with a sandwiching ultrathin ferroelectric film

Abstract

The high operating voltage is a primary issue preventing the commercial application of the ferroelectric organic field-effect transistor (Fe-OFET) nonvolatile memory (NVM). In this work, we propose a novel route to resolve this issue by employing two ultrathin AlOX interfacial layers sandwiching an ultrathin ferroelectric polymer film with a low coercive field, in the fabricated flexible Fe-OFET NVM. The operation voltage of Fe-OFET NVMs decreases with the downscaling thickness of the ferroelectric film. By inserting two ultrathin AlOX interfacial layers at both sides of the ultrathin ferroelectric film, not only the gate leakage is prominently depressed but also the mobility is greatly improved. Excellent memory performances, with large mobility of 1.7 ~ 3.3 cm2 V−1 s−1, high reliable memory switching endurance over 2700 cycles, high stable data storage retention capability over 8 × 104 s with memory on-off ratio larger than 102, are achieved at the low operating voltage of 4 V, which is the lowest value reported to data for all Fe-OFET NVMs. Simultaneously, outstanding mechanical fatigue property with the memory performances maintaining well over 7500 bending cycles at a bending radius of 5.5 mm is also achieved in our flexible FE-OFET NVM.

Highly Robust Flexible Ferroelectric Field Effect Transistors Operable at High Temperature with Low‐Power Consumption

“…Under a negative gate voltage of −6 V, the polarization of PZT is reversed downward, resulting in depletion of channel charges at PZT/ZnO interface and thus low current. The memory window is around 1.5 V when V GS sweeps from −6 to +6 V, consistent with coercive voltage estimated from P‐E loop, suggesting that the flexible FeFETs can operate as well as be programmed with a low voltage, much smaller than other FeFETs using polymeric ferroelectric gate that is usually in the range from ±20 to ±40 V, though lower coercive voltage of 4 V has also been demonstrated in ultrathin P(VDF‐TrFE‐CTFE), at the expense of low on/off ratio. The device also possesses good retention characteristics critical for memory application as shown in Figure b, acquired by measuring the on/off current as a function of time after applying a writing/erasing pulse of ± 6 V to the gate electrode at a fixed drain voltage of 0.5 V. Note that between readout measurements, all the terminals of FeFET are left floating for retention characterization, reflecting nonvolatile nature of the device.…”

EGOFET Gated by a Molecular Electronic Switch: A Single‐Device Memory Cell

“…The main potential advantages of EGOFET‐based memory architectures with respect to OFETs are the high‐current/low‐voltage operation to write/read/erase and the possibility to work with biological solutions in vitro and potentially in vivo. Nevertheless, one disadvantage is that the EGOFET relies on ion displacement, and this may limit the switching speed of the memory with respect to the OFET.…”

Organic Field‐Effect Transistor Nonvolatile Memories with Hydroxyl‐Rich Polymer Materials as Functional Gate Dielectrics

“…Among them, organic field‐effect transistors (OFETs) based nonvolatile memories (NVMs) exhibited the most attractive features owing to their good processing compatibility with integrated circuits, nondestructive reading‐out, and potential multi‐bit data storage in one cell . Depending on the mechanism of data storage, OFET‐NVM devices are divided into two types: charge‐trapping type and polarization‐type …”

“…For polarization‐type OFET‐NVMs, the dipole moments of the polymer materials as the gate dielectrics can be realigned to induce two polarization states at the W/E operations, which modulate the channel current to be binary 0 and 1 states, respectively. Among the reported polarization‐type OFET‐NVMs, the most used gate dielectric materials are ferroelectric polymer polyvinylidene fluoride (PVDF) and its derivatives for their advantages of short switching time and stable remnant polarization ( P r ) . However, the rough surface morphology of ferroelectric polymer gate dielectric layers because of their crystalline nature often induced a small field‐effect mobility and visible leakage current, which reduced the memory performances .…”