The 3D vertical ferroelectric tunneling junction (FTJ) of bilayer antiferroelectric (AFE) Hf 1-x Zr x O 2 (HZO) and Al 2 O 3 has been demonstrated for NAND-compatible feasibility. A bilayer-type FTJ ...is explored for the designs of the dielectric interlayer Al 2 O 3 0 nm to 4 nm and the ferroelectric type, while the current mechanism is revealed. The multilevel AFE-FTJ is exhibited for both the Program and Erase operations and realizes a synaptic device. High-density emerging memory and computing-in-memory (CiM) are in high demanded for the future era and can be feasible by the proposed vertical FTJ.
Pt(II) metal complexes are known to exhibit strong solid‐state aggregation and are promising for realization of efficient emission in fabrication of organic light emitting diodes (OLED) with nondoped ...emitter layer. Four pyrimidine–pyrazolate based chelates, together with four isomeric Pt(II) metal complexes, namely: Pt(pm2z)2, Pt(tpm2z)2, Pt(pm4z)2, and Pt(tpm4z)2, are isolated and systematically investigated for their structure–property relationships for practical OLED applications. Detailed single molecular and aggregated structures are revealed by photophysical and mechanochromic measurements, grazing‐incidence X‐ray diffraction, and theoretical approaches. These results suggest that these Pt(II) emitters pack like a deck of playing cards under vacuum deposition, and their emission energy is not only affected by the single molecular designs, but notably influenced by their intermolecular packing interaction, i.e., Pt···Pt separations that are arranged in the order: Pt(tpm4z)2 > Pt(pm4z)2 > Pt(tpm2z)2 > Pt(pm2z)2. Nondoped OLED with emission ranging from green to red are prepared, to which the best performances are recorded for Pt(tpm2z)2, giving maximum external quantum efficiency (EQE) of 27.5% at 103 cd m−2, maximum luminance of 2.5 × 105 cd m−2 at 17 V, and with stable CIEx,y of (0.56, 0.44).
Nondoped organic light emitting diodes (OLED) devices with emission ranging from green to red are prepared using four Pt(II) complexes that exhibit strong solid‐state aggregation and horizontal aligned transition dipole moments, while their stacking characteristics also play a crucial role in manipulating the emission properties.
The bilayer-based Antiferroelectric Tunneling Junction (AFTJ) with ferroelectric (FE) HfZrO 2 (HZO) and dielectric (DE) Al 2 O 3 demonstrates a current ratio of <inline-formula> <tex-math ...notation="LaTeX">> 100\times </tex-math></inline-formula>, a TER (tunneling electroresistance) of <inline-formula> <tex-math notation="LaTeX">> 50\times </tex-math></inline-formula>, multilevel states, <inline-formula> <tex-math notation="LaTeX">> 10^{4} </tex-math></inline-formula> sec retention, and a cycling endurance as high as 10 8 . The concept of tunneling current through DE in an antiferroelectric (AFE) system enhances the capacity to modulate the current/TER ratio and makes the AFTJ feasible for low-power crossbar eNVM (embedded nonvolatile memory) applications.
Atomic layer deposition (ALD)-based TiN electrode on ferroelectric HfZrO 2 metal/ferroelectric/metal (MFM) capacitor and ferroelectric field-effect transistor (FeFET) is demonstrated experimentally ...with weight transfer, that is, <inline-formula> <tex-math notation="LaTeX">\Delta {P} </tex-math></inline-formula>, per pulse analysis through consecutive alternating potentiation/depression (Pot./Dep.) training pulses. The weight training pulse schemes are studied to have symmetric and linear synapse weight transfer to increase the accuracy and accelerate the deep neural network (DNN) training. With ALD TiN inserted, <inline-formula> <tex-math notation="LaTeX">\alpha _{p} / \alpha _{d} = -0.63 </tex-math></inline-formula> / −0.84, asymmetry <inline-formula> <tex-math notation="LaTeX">\vert \alpha _{p} - \alpha _{d}\vert =0.21 </tex-math></inline-formula>, and polarization modulation ratio (Pot./Dep.) = 97%/98% are achieved for MFM capacitor, and <inline-formula> <tex-math notation="LaTeX">\alpha _{p} / \alpha _{d} = -1.32 </tex-math></inline-formula> / −1.88, asymmetry <inline-formula> <tex-math notation="LaTeX">\vert \alpha _{p} - \alpha _{d}\vert =0.56 </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">G_{\text {max}} / G_{\text {min}} > 10\times </tex-math></inline-formula> are delivered for FeFET.
Opposite polarity cycling recovery (OPCR) is proposed to completely restore a fatigued antiferroelectric (AFE) capacitor back to its initial state, thereby extending the endurance number of switching ...cycles for AFE-RAM. A comprehensive model exclusive to AFE with unipolar cycling is revealed to achieve unlimited endurance, and the unipolar cycling with OPCR is experimentally demonstrated to accumulate Formula Omitted cycles, while achieving the nondegradation and complete restoration of the remnant polarization (Formula Omitted). Furthermore, the proposed OPCR achieves a recovery time ratio of 0% (Formula Omitted), which indicates no extra time to spend for the recovery procedure.
Asymmetric field cycling recovery (AFCR) with alternating opposite low <inline-formula> <tex-math notation="LaTeX">{E} </tex-math></inline-formula>-field cycling is proposed to restore a fatigued ...ferroelectric (FE) capacitor and is experimentally demonstrated for up to <inline-formula> <tex-math notation="LaTeX">10^{{12}} </tex-math></inline-formula> switching cycles, thereby extending the endurance of FeRAM. Positive and negative asymmetric minor loops (AmLs) with AFCR exhibit nondegradation and complete restoration of <inline-formula> <tex-math notation="LaTeX">\Delta 2{P}_{\text {r}} </tex-math></inline-formula> toward unlimited endurance operation. Furthermore, an FE random access memory (FeRAM) array circuit with an inverting amplifier is designed to simultaneously execute Write/Read and Recovery procedures via the AFCR scheme.
A double-HZO (HfZrO 2 ) FeFET (ferroelectric FET) with nonidentical ferroelectric thicknesses is experimentally demonstrated with as low as <inline-formula> <tex-math notation="LaTeX">\vert ...{V}_{P/{E}}\vert = {5} </tex-math></inline-formula> V, 2-bit endurance > 10 5 cycles and retention > 10 4 s. Inserting an insulator to separate the ferroelectric layers and avoid the monoclinic formation of a thick Fe-HZO (ferroelectric-HZO) is a useful method to enhance the MW (memory window) for MLC (multilevel cell) applications. Double-HZO has a lower ER (error rate) and shows a 600X improvement compared to single-HZO. The stacked HZO FeFET has potential as an MLC for high-density NVM (nonvolatile memory) applications.
The voltage amplification of a ferroelectric layer was studied for advanced complementary metal–oxide–semiconductor (CMOS) applications. To match the capacitance for negative-capacitance field-effect ...transistors (NC-FETs), a method of adjusting the MOS capacitance is proposed by optimizing the width (
W
) and height/depth (
H
) in two types of ferroelectric gate-stack 2D metal-oxide semiconductor capacitor (MOSCAP) structures: a fin-like structure and a trench structure. The capacitance of the semiconductor was modeled to match that of the ferroelectric films to obtain hysteresis-free operation (Δ
V
T
=
V
T
, for –
V
T,rev
~ 0) and achieve voltage amplification (
A
V
). The optimized conditions are found to be
H
= 19.3 nm and 24.3 nm to achieve the criterion with
A
V
> 50 for the fin-like and trench structure, respectively. Subsequently, the structure was extended to a three-dimensional (3D) fin-shaped field-effect transistor (FinFET) to evaluate the effects of varying geometrical parameters such as the fin spacing (
F
S
). Tuning
F
S
can not only enhance the on-current but also decrease the subthreshold swing in the off-current region. For the FET, the use of the optimum
F
S
value of 30 nm helps the FinFETs achieve capacitance matching with
A
V
> 30. The subthreshold swing of the NC-FinFET is improved by about 47% for
H
FinFET
/
W
FinFET
~ 3 and
F
s
/
H
FinFET
~ 1.2 as compared with the conventional FinFET. The concept of coupling the polarized Hf-based oxide in NC-FETs that is demonstrated to be feasible herein is thus practicable using current CMOS architectures.
Functional 2-pyrazolyl-6-phenylpyridine chelatesnamely, (pzpyphBu)H2 and (pzpyphCF3 )H2 and phosphinesare successfully employed in the preparation of emissive Ir(III) metal complexes, for which ...the reaction with phosphine such as PPh3, PPh2Me, and PPh2(CH2Ph) afford corresponding Ir(III) complexes Ir(pzpyphBu)(PPh3)2H (1a), Ir(pzpyphCF3 )(PPh2R)2H (2a–2c), R = Ph, Me, CH2Ph, which also show an equatorial coordinated hydride. In contrast, treatment with 1,2-bis(diphenylphosphino)benzene (dppb) and 1,2-bis(diphenylphosphino)ethane (dppe) yields the isomeric products Ir(pzpyphBu)(dppb)H (3a) and Ir(pzpyphBu)(dppe)H (3b), for which the distinctive, axial hydride undergoes rapid chlorination, forming chlorinated complexes Ir(pzpyphBu)(dppb)Cl (4a) and Ir(pzpyphBu)(dppe)Cl (4b), respectively. On the other hand, upon extensive heating of 2c, one of its coordinated PPh2(CH2Ph) exhibits benzyl cyclometalation and hydride elimination to afford Ir(pzpyphCF3 )(PPh2R)(PPh2R′) (5c and 6c) R = CH2Ph and R′ = CH2(o-C6H4) as the kinetic and thermodynamic products, respectively. Their structural, photophysical, and electrochemical properties are examined and further affirmed by the computational approaches.
This study was conducted to determine the effect of acute aerobic exercise on executive function in children with attention deficit hyperactivity disorder (ADHD). Forty children with ADHD were ...randomly assigned into exercise or control groups. Participants in the exercise group performed a moderate intensity aerobic exercise for 30 min, whereas the control group watched a running/exercise-related video. Neuropsychological tasks, the Stroop Test and the Wisconsin Card Sorting Test (WCST), were assessed before and after each treatment. The results indicated that acute exercise facilitated performance in the Stroop Test, particularly in the Stroop Color-Word condition. Additionally, children in the exercise group demonstrated improvement in specific WCST performances in Non-perseverative Errors and Categories Completed, whereas no influences were found in those performances in the control group. Tentative explanations for the exercise effect postulate that exercise allocates attention resources, influences the dorsolateral prefrontal cortex, and is implicated in exercise-induced dopamine release. These findings are promising and additional investigations to explore the efficacy of exercise on executive function in children with ADHD are encouraged.
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