ACS Applied Electronic Materials最新文献

To satisfy the needs of the current technological world that demands high performance and efficiency, a deep understanding of the whole fabrication process of electronic devices based on low-dimensional materials is necessary for rapid prototyping of devices. The fabrication processes of such nanoscale devices often include exposure to an electron beam. A field effect transistor (FET) is a core device in current computation technology, and FET configuration is also commonly used for extraction of electronic properties of low-dimensional materials. In this experimental study, we analyze the effect of electron beam exposure on electrical properties of individual WS₂ nanotubes in the FET configuration by in-operando transport measurements inside a scanning electron microscope. Upon exposure to the electron beam, we observed a significant change in the resistance of individual substrate-supported nanotubes (by a factor of 2 to 14) that was generally irreversible. The resistance of each nanotube did not return to its original state even after keeping it under ambient conditions for hours to days. Furthermore, we employed Kelvin probe force microscopy to monitor surface potential and identified that substrate charging is the primary cause of changes in nanotubes' resistance. Hence, extra care should be taken when analyzing nanostructures in contact with insulating oxides that are subject to electron exposure during or after fabrication.

Germanium (Ge), the next-in-line group-IV material, bears great potential to add functionality and performance to next-generation nanoelectronics and solid-state quantum transport based on silicon (Si) technology. Here, we investigate the direct epitaxial growth of two-dimensional high-quality crystalline Ge layers on Si deposited at ultralow growth temperatures (T _Ge = 100-350 °C) and pristine growth pressures (≲10^-10 mbar). First, we show that a decreasing T _Ge does not degrade the crystal quality of homoepitaxial Ge/Ge(001) by comparing the point defect density using positron annihilation lifetime spectroscopy. Subsequently, we present a systematic investigation of the Ge/Si(001) heteroepitaxy, varying the Ge coverage (Θ_Ge, 1, 2, 4, 8, 12, and 16 nm) and T _Ge (100-300 °C, in increments of 50 °C) to assess the influence of these parameters on the layer's structural quality. Atomic force microscopy revealed a rippled surface topography with superimposed grainy features and the absence of three-dimensional structures, such as quantum dots. Transmission electron microscopy unveiled pseudomorphic grains of highly crystalline growth separated by defective domains. Thanks to nanobeam scanning X-ray diffraction measurements, we were able to evidence the lattice strain fluctuations due to the ripple-like structure of the layers. We conclude that the heteroepitaxial strain contributes to the formation of the ripples, which originate from the kinetic limitations of the ultralow temperatures.

The purpose of the study was to evaluate the effects of tact and match-to-sample instructions on the increase and maintenance of intraverbal responses to subcategorical questions (i.e., naming multiple items in a subcategory of a category). Three Chinese children on the autism spectrum (2 boys, 1 girl, aged 6-8 years old) participated in this study. Results indicated that intraverbal responses to subcategorical questions emerged or increased for most subcategories for all three participants following the completion of instruction without direct training.

Purpose: The aim of this study was to validate the low anterior resection syndrome (LARS) score questionnaire in the Vietnamese language among Vietnamese patients who underwent sphincter-preserving surgery for rectal cancer.

Methods: The LARS score questionnaire was translated from English into Vietnamese and then back-translated as recommended internationally. From January 2018 to December 2020, 93 patients who underwent sphincter-preserving surgery completed the Vietnamese version of the LARS score questionnaire together with an anchored question assessing the influence of bowel function on quality of life. To validate test-retest reliability, patients were requested to answer the LARS score questionnaire twice.

Results: Ninety-three patients completed the LARS score questionnaire, of whom 89 responded twice. The patients who responded twice were included in the analysis of test-retest reliability. Fifty-eight patients had a "major" LARS score. The LARS score was able to discriminate between patients who were obese and those who were not (P<0.001) and between the LAR and AR procedures (P<0.001). Age and sex were not associated with higher LARS scores (P=0.975). There was a perfect fit between the quality of life category question and the LARS score in 56.2% of cases, and a moderate fit was found in 42.7% of cases, showing reasonable convergent validity. The test-retest reliability of 89 patients showed a high intraclass correlation coefficient.

Conclusion: The Vietnamese version of the LARS score questionnaire is a valid tool for measuring LARS.

Electronics based on natural or degradable materials are a key requirement for next-generation devices, where sustainability, biodegradability, and resource efficiency are essential. In this context, optimizing the molecular chemical structure of organic semiconductor compounds (OSCs) used as active layers is crucial for enhancing the efficiency of these devices, making them competitive with conventional electronics. In this work, honey-gated organic field-effect transistors (HGOFETs) were fabricated using four different perylene derivative films as OSCs, and the impact of the chemical structure of these perylene derivatives on the performance of HGOFETs was investigated. HGOFETs were fabricated using naturally occurring or low-impact materials in an effort to produce sustainable systems that degrade into benign end products at the end of their life. It is shown that the second chain of four carbons at the imide position present in perylenes N,N'-bis(5-nonyl)-perylene-3,4,9,10-bis(dicarboximide) (PDI) and N,N'-bis(5-nonyl)-1-naphthoxyperylene-3,4,9,10-bis(dicarboximide) (PDI-ONaph) reduces π-stacking interaction in the active layer, leading to lower AC conductivity and the non-functionality of HGOFETs. On the other side, the chain-on molecular orientation in the film of N,N'-dibutylperylen-3,4:9,10-bis(dicarboximide) (BuPTCD) was fundamental for the efficiency of HGOFETs, showing a better performance than the HGOFETs of N,N'-bis(2-phenylethyl)-3,4:9,10-bis(dicarboximide) (PhPTCD), which has a face-on molecular orientation. Finally, the HGOFETs of BuPTCD and PhPTCD are good candidates as UV light detectors and are used for the detection of UV radiation.

The 1530 nm emission of the Er intra-4f transition (⁴I_13/2 → ⁴I_15/2) is essential for telecom communication because it corresponds to the minimum-loss window of silica optical fibers. Herein, we develop a metal–semiconductor–metal structured light source based on O–Er co-doped MoS₂. The electroluminescence device exhibits the 1530 nm emission at low drive voltages (<5 V), which is beneficial from the impact excitation with the space–charge-limited conduction mechanism. The characteristic of symmetric structure allows the devices to exhibit consistent electrical and electroluminescence performance at positive and negative voltages. The O doping contributes to such high-current electrical behavior, and the Er doping leads to increased trap-filled-limited voltage due to increased trap density. This work lays the foundation for developing near-infrared light sources constructed with two-dimensional materials.

Self-induced spin Hall effect and self-torque hold great promise in the field of spintronics, offering a path toward highly efficient spin-to-charge interconversion, a pivotal advancement for data storage, sensing devices, or unconventional computing. In this study, we investigate the spin-charge current conversion characteristics of chemically disordered ferromagnetic single FePt thin films by spin-pumping ferromagnetic resonance experiments performed on both a resonance cavity and on patterned devices. We clearly observe a self-induced signal in a single FePt layer. The sign of a single FePt spin pumping voltage signal is consistent with a typical bilayer with a positive spin Hall angle layer such as that of Pt on top of a ferromagnet (FM), substrate//FM/Pt. Structural analysis shows a composition gradient due to natural oxidation at both FePt interfaces, with the Si substrate and with the air. The FePt-thickness dependence of the self-induced charge current produced allowed us to obtain λ_FePt = (1.5 ± 0.1) nm and self-induced θ_self-FePt = 0.047 ± 0.003, with efficiency for reciprocal effects applications θ_self-FePt × λ_FePt = 0.071 nm which is comparable to that of Pt, θ_SH-Pt × λ_Pt = 0.2 nm. The spin pumping voltage is also observed in a symmetrical stacking, Al/FePt/Al with a lower overall efficiency. Moreover, by studying bilayer systems such as Si//FePt/Pt and Si//Pt//FePt we independently could extract the individual contributions of the external inverse spin Hall effect of Pt and the self-induced inverse spin Hall effect of FePt. Notably, this method gives consistent values of charge currents produced due to only self-induced inverse spin Hall effect in FePt layers. These results advance our understanding of spin-to-charge interconversion mechanisms in composite thin films and pave the way for the development of next-generation spintronics devices based on self-torque.

Rational design of the multidimensional structure of self-supporting composite electrode materials is an effective way to maintain the structural stability of supercapacitors and the efficient energy storage performance of ion and electron transport. Here, layered double hydroxide (LDH) composite electrodes (CoMn LDH@CoNi LDH/NF, CM@CN LDH) with graded structure and unique sea urchin-like distribution are prepared on nickel foam (NF) by the solvothermal method. The synergistic effect of the dual-LDH leads to increased layer spacing and provides more electrochemically accessible surfaces together with short and effective ion transport paths, which helps to accommodate a large number of active sites to achieve a rapid Faraday oxidation–reduction reaction. The results show that the CM@CN LDH-S1 in the three-electrode system exhibits an excellent specific capacitance of 2381.3 F·g^–1 at a current density of 1 A·g^–1. The assembled asymmetric supercapacitor device has a high specific capacitance of 240.8 F·g^–1 at 1 A·g^–1, a high energy density of 75.3 Wh·kg^–1, and an excellent cycling performance (85.2% initial retention after more than 5000 cycles at 5 A·g^–1), indicating that the graded nanostructure dual-LDH material has excellent application potential.

Radio frequency (RF) switches used in reconfigurable antennas often face reliability issues such as low isolation, high insertion loss, and limited power handling capability. To address these issues, this study presents a mechanical RF switch with high power capability that uses liquid metals as wetted contacts. It utilizes the rotation of a DC motor, together with a gear-rack meshing drive, to push the movable contact electrode to achieve contact or disconnection with the fixed electrode contacts wetted by eutectic gallium–indium alloy, thus realizing the on/off action of this RF switch. The electrode contacts are made of tin-plated copper, experimentally verified to have good wetting characteristics and low contact resistance with gallium-based liquid metals. For RF performance, small-signal measurements show that the RF switch has a return loss of less than −10 dB, an insertion loss of less than 3.5 dB, and an isolation of more than 13 dB from 0 to 5 GHz, while large-signal measurements suggest that it can handle a maximum power of 45.1 dBm in the 0–3 GHz band. This study also confirms the good performance of the designed RF switch for frequency reconfiguration of microstrip antennas.