Advanced Electronic Materials
ISSN / EISSN : 2199-160X / 2199-160X
Published by: Wiley-Blackwell (10.1002)
Total articles ≅ 2,334
Latest articles in this journal
Advanced Electronic Materials; https://doi.org/10.1002/aelm.202100739
The effects of halide-ligand exchange and Cu and Ag doping are studied on structural, optical, and electrical properties of four monolayer CdSe nanoplatelet (NPL) and NPL thin films. Combinational study shows that NH4Cl-treatment on CdSe NPL and NPL thin films show tetragonal lattice distortion of NPL, side-to-side attachment between NPLs, bathochromic shift in absorption spectra, and complete quenching of band-edge and dopant-induced emissions. First-principle calculations reveal that Cl creates states below valence band maximum while Ag and Cu dopants create acceptor-like states, explaining the change of their optical property. Field-effect transistors are fabricated to investigate the effect of doping and reduced interplatelet distance on electrical properties of CdSe NPL thin films, demonstrating Cu and Ag dopants mitigate n-type character of CdSe NPL thin films. Temperature-dependent electrical characterization is conducted to further understand charge transport behavior depending on the existence of dopants. This work provides scientific information on the influence of surface chemistry and impurity doping on quantum confined semiconductors and new directions for the design of high-performance nanomaterial-based electronic and optoelectronic devices.
Advanced Electronic Materials; https://doi.org/10.1002/aelm.202100729
2D nanomaterials such as graphene and transition metal dichalcogenides have attracted great interest as future electronic materials, especially for application in next-generation displays, owing to their extraordinary electrical, mechanical, and optical properties. In order to achieve 2D material-based practical devices, it is essential to heal the graphene defects which are inevitably generated during chemical vapor deposition-based large-area synthesis and transfer process, through doping technology. In this article, a novel approach for selective defect-healing of graphene with electrodeposited gold nanoparticles is proposed, where the defect-healed graphene source/drain electrodes are integrated with p-type tungsten diselenide (WSe2) thin-film transistors (TFTs), for the first time. This proposed device shows greatly enhanced electrical characteristics (increase of carrier mobility about ≈230.8%) by selective defect-healing of graphene, and the performance improvement mechanism is systematically investigated in terms of conductivity and Schottky barrier engineering of graphene/WSe2 interface. Also, a long-term stability of defect-healed graphene electrode is achieved over a long period of a month, which is enabled by a polymer-based passivation layer that maintains the doping effects of defect-engineered graphene. The authors’ findings therefore provide a new strategy for developing graphene electrode-based high-performance TFTs, and reveal the enormous potential of graphene as an innovative conductor for prospective displays.
Advanced Electronic Materials; https://doi.org/10.1002/aelm.202100650
The switching dynamics of ferroelectric polarization under electric fields depends on the availability of screening charges in order to stabilize the switched polarization. In ferroelectrics, thin films with exposed surfaces investigated by piezoresponse force microscopy (PFM), the main source of external screening charges is the atmosphere and the water neck, and therefore relative humidity (RH) plays a major role. Here, it is shown how the dynamic writing of domains in BaTiO3 thin films changes by varying scanning speeds in the range of RH between 2.5% and 60%. The measurements reveal that the critical speed for domain writing, which is defined as the highest speed at which electrical writing of a continuous stripe domain is possible, increases non-monotonically with RH. Additionally, the width of line domains shows a power law dependence on the writing speed, with a growth rate coefficient decreasing with RH. The size of the written domains at a constant speed as well as the creep-factor μ describing the domain wall kinetics follow the behavior of water adsorption represented by the adsorption isotherm, indicating that the screening mechanism dominating the switching dynamics is the thickness and the structure of adsorbed water structure and its associated dielectric constant and ionic mobility.
Advanced Electronic Materials; https://doi.org/10.1002/aelm.202100669
Neuromorphic systems provide a potential solution for overcoming von Neumann bottleneck and realizing computing with low energy consumption and latency. However, the neuromorphic devices utilized to construct the neuromorphic systems always focus on artificial synapses and neurons, and neglected the important role of astrocyte cells. Here, an astrocyte memristor is demonstrated with encapsulated yttria-stabilized zirconia (YSZ) to emulate the function of astrocyte cells in biology. Due to the high oxygen vacancy concentration and resultant high ionic conductivity of YSZ, significantly lower forming and set voltages are achieved in the artificial astrocyte, along with high endurance (>1011). More importantly, the nonlinearity in current-voltage characteristics that usually emerge as the testing cycle increases can be depressed in the astrocyte memristor, and the nonlinearity can also be reversed by applying a refresh operation, which implements the role of biological astrocyte in maintaining the normal activity of neurons. The recovery of linearity can dramatically improve the accuracy of Modified National Institute of Standards and Technology dataset classification from 62.98% to 94.75% when the inputs are encoded in voltage amplitudes. The astrocyte memristor in this work with improved performance and linearity recovery characteristics can well emulate the function of astrocyte cells in biology and have great potential for neuromorphic computing.
Advanced Electronic Materials; https://doi.org/10.1002/aelm.202100592
The zinc cobaltite possesses merit of high theoretical specific capacity. However, issues of low conductivity and volume expansion during lithiation and delithiation lead to severe capacity fading. In this work, a porous zinc cobaltite/carbon composite nanofiber is synthesized with a metal–organic frameworks (MOFs) structure through electrospinning, in situ growth, and hydrothermal reaction. The obtained zinc cobaltite/carbon composite nanofibers have an improved specific surface area (90.61 m2 g-1), enabling excellent electrochemical performance as anode materials in Li-ion batteries. Briefly, a high initial discharge capacity of 2468 mAh g-1 and reversible capacity of 2008 mAh g-1 after the 200 cycles, and an outstanding rate capability of 937 mAh g-1 at 2 A g-1 are achieved. The capacity fading of MOFs–zinc cobaltite/carbon composite nanofibers is significantly improved, which can be attributed to the following reasons: i) the MOFs structure effectively relieve the strain stemming from volume expansion of transition metal; ii) the abundance of mesoporous structure facilitates the electron transport for Li+ diffusion rate by shortening the Li-ion diffusion path during lithiation/delithiation process; iii) the carbon nanofibers with excellent conductivity enable efficient conduction efficiency of lithium ions and electrons. The proposed strategy offers a new perspective to prepare high-performance electrode for lithium-ion batteries.
Advanced Electronic Materials; https://doi.org/10.1002/aelm.202100591
Physically blending semiconducting conjugated polymers with elastomeric materials and precisely controlling the resulting film structure provides an effective strategy to obtain intrinsically stretchable semiconducting polymers. Here, vertically phase-separated ultrathin poly(3-hexylthiophene) (P3HT) and polystyrene-b-polyisoprene-b-polystyrene (SIS) blend films are developed for one-step fabrication of semiconductor and insulator layers of organic field effect transistors (OFETs). The phase-separated structure, surface morphology, and tensile deformation are characterized by UV–vis absorption spectroscopy, atomic force microscopy, and optical microscopy. The blend film device maintains 43% of its mobility compared with 0.1% mobility of the pristine P3HT films after 50% stretch. The deformability of the films is efficiently improved by blending proved by both the finite element analysis and the dichroic ratio measurements. The P3HT/SIS blended films possess reproducible properties under 200 continuous stretch–release cycles at a strain of 50% without significantly reduced mobilities. The fully-stretchable OFETs on polydimethylsiloxane substrate are also investigated and show a stretchability up to 70% and good electrical recovery properties after stretch–release process. The vertical phase-separated structure obtained by the blends provides an effective way to easily fabricate stretchable devices with a balance between their mechanical and electrical properties.
Advanced Electronic Materials; https://doi.org/10.1002/aelm.202100485
Originally based on phenomenological observations, the Janovec–Kay–Dunn (JKD) scaling law has been historically used to describe the dependence of the ferroelectric coercive fields (Ec) on a critical length scale of the material, wherein the film thickness (t) is considered the length scale, and Ec ∝ t−2/3. Here, for the first time, a JKD-type scaling behavior is reported in an antiferroelectric material, using the ultra-thin films of prototypical flourite-structure binary oxide, zirconia. In these films, a decrease in the ZrO2 layer thickness from 20 nm to 5.4 nm leads to an increase in critical fields for both nonpolar-to-polar (Ea), and polar-to-nonpolar (Ef) transitions, accompanied by a decrease in the average crystallite size, and an increase in the tetragonal distortion of the non-polar P42/nmc ground state structure. Notably, the -2/3 power law as in the JKD law holds when average crystallite size (d), measured from glancing-incident X-ray diffraction, is considered as the critical length scale—i.e., Ea, Ef ∝ d−2/3. First principles calculations suggest that the increase of tetragonality in thinner films contributes to an increase of the energy barrier for the transition from the non-polar tetragonal ground state to the field-induced polar orthorhombic phase, and in turn, an increase in Ea critical fields. These results suggest a de-stabilization of the ferroelectric phase with a decreasing thickness in antiferroelectric ZrO2, which is contrary to the observations in its fluorite-structure ferroelectric counterparts. With the recent interests in utilizing antiferroelectricity for advanced semiconductor applications, our fundamental exposition of the thickness dependence of functional responses therein can accelerate the development of miniaturized, antiferroelectric electronic memory elements for the complementary metal-oxide-semiconductor based high-volume manufacturing platforms.
Advanced Electronic Materials; https://doi.org/10.1002/aelm.202100717
Ferroelectric materials have aroused increasing interest in the field of self-powered ultraviolet (UV) photodetectors for their polarization electric field induced photovoltaic (PV) effect. However, the device performance of currently reported ferroelectric-based self-powered UV detectors remains to be improved. Herein, achievement of high-performance ZnO/Pb0.95La0.05Zr0.54Ti0.46O3 (PLZT) heterojunction-based self-powered UV photodetectors is demonstrated by coupling the ferroelectric depolarization electric field (Edp) and built-in electric field (EZnO/PLZT) at the ZnO/PLZT interface with a II-type energy band alignment. The ZnO/PLZT heterojunction-based self-powered UV photodetector shows a remarkable responsivity (R = 3.96 mA W−1) and detectivity (D* = 6.6 × 1010 Jones), which are by two orders of magnitude larger than those of the device that are produced under similar conditions without ZnO layer. Moreover, the ZnO/PLZT heterojunction-based device exhibits a rapid response (rise time τr = 0.04 s, decay time τd = 0.05 s), which is faster than most of previous reports. The excellent device performance of the ZnO/PLZT heterojunction-based device can be attributed to the efficient separation and transport of photogenerated carriers caused by the constructive coupling of Edp and EZnO/PLZT. This work offers a feasible and effective strategy for the performance improvement of ferroelectric-based self-powered UV detectors.
Advanced Electronic Materials; https://doi.org/10.1002/aelm.202100434
In improper ferroelectrics, the spontaneous ordering is typically driven by a structural distortion or a magnetic spin alignment. The induced electric polarization is only a secondary effect. This dependence is a rich source for unusual phenomena and ferroelectric domain configurations for proper, polarization-driven ferroelectrics. This study focuses on the polar domain structure and the hysteretic behavior at the ferroelectric phase transition in Ca3Mn1.9Ti0.1O7 as a representative of the recently discovered hybrid improper ferroelectric class of multiferroics. Combining optical second harmonic generation and Raman spectroscopy gives access to the spontaneous structural distortion and the resulting improper electric polarization. This study shows that hybrid improper ferroelectrics contrast proper and improper ferroelectrics in several ways. Most intriguingly, adjacent ferroelectric domains favor head-to-head and tail-to-tail domain walls over charge-neutral configurations. Furthermore, the phase transition occurs in an asymmetric fashion. The regime of phase coexistence of the nonpolar and polar phases shows a clear and abrupt upper temperature limit. In contrast, the coexistence toward low temperatures is best described as a fade-out process, where 100-nm-sized islands of the nonpolar phase expand deep into the polar phase.
Advanced Electronic Materials; https://doi.org/10.1002/aelm.202100420
Endurance of ferroelectric HfO2 needs to be enhanced for its use in commercial memories. This work investigates fatigue in epitaxial Hf0.5Zr0.5O2 (HZO) instead of polycrystalline samples. Using different substrates, the relative amount of orthorhombic (ferroelectric) and monoclinic (paraelectric) phases is controlled. Epitaxial HZO films almost free of parasitic monoclinic phase suffer severe fatigue. In contrast, fatigue is mitigated in films with a greater amount of paraelectric phase. This suggests that fatigue can be intrinsically pronounced in ferroelectric HZO. It is argued that the enhancement of endurance in films showing coexisting phases results from the suppression of pinned domain propagation at ferroelectric–paraelectric grain boundaries, in contrast with a rapid increase of the size of the pinned domains in single ferroelectric regions.