Search

Highcarrier concentration and low mobility in Bi2Se3 hide thetopological surface states (TSS). In the 2D ternary topological insulator (TI) Bi2–xSbxSe3,compensatory Sb doping regulates the carrier concentration and mobility withambipolar performance, together with the ultrathin thickness; these factorsmake the TSS in the 2D ternary TI Bi2–xSbxSe3 more observable. Here, a chemical vapor deposition (CVD) method is provided for synthesizing ultrathin Sb‐doped Bi2Se3 nanoplates with dimensions of 2–126 nm in thickness, 3–100 µm in lateral size, and an average Sb doping ranging from 0.15 ≤ x ≤ 0.75. Bi2–xSbxSe3 field effect transistors and Hall devices are manufactured to determine the carrier concentration and mobility of the obtained Bi2–xSbxSe3 nanoplates. These findings demonstrate that the 2D carrier concentration for Bi2–xSbxSe3 nanoplates can decrease up to 1.6 × 1012 cm–2. Furthermore, field‐effect mobility and Hall mobility of up to 3411 cm2 V–1s–1 and 6462 cm2 V–1 s–1, respectively, are realized. A strong ambipolar field effect is found in low‐carrier‐density Bi2–xSbxSe3 nanoplates, proving that these nanostructures may be freely controlled in terms of carrier type and concentration. The synthesis of high‐quality Bi2–xSbxSe3 nanoplates with low‐carrier concentration and high‐mobility provides a platform for investigating TI characteristics more clearly. [ABSTRACT FROM AUTHOR]

The increase of gate leakage current when the gate dielectric layer is thinned is a key issue for device scalability. For scaling down the integrated circuits, a thin gate dielectric layer with a low leakage current is essential. Currently, changing the dielectric layer material or enhancing the surface contact between the gate dielectric and the channel material is the most common way to reduce gate leakage current in devices. Herein, we report a technique of enhancing the surface contact between the gate dielectric and the metal electrode, that is constructing an Au/Al2O3/Si metalâ€"oxideâ€"semiconductor device by replacing the typical evaporated electrode/dielectric layer contact with a transferred electrode/high- Îş dielectric layer contact. The contact with a mild, non-invasive interface can ensure the intrinsic insulation of the dielectric layer. By applying 2â€"40 nm Al2O3 as the dielectric layer, the current densityâ€"electrical field (J â€" E) measurement reveals that the dielectric leakage generated by the transferred electrode is less than that obtained by the typical evaporated electrode with a ratio of 0.3 × 101 ∼ 5 × 106 at V bias = 1 V. Furthermore, at J  = 1 mA cmâˆ'2, the withstand voltage can be raised by 100â€"102 times over that of an evaporated electrode. The capacitanceâ€"voltage (C â€" V) test shows that the transferred metal electrode can efficiently scale the equivalent oxide layer thickness (EOT) to 1.58 nm, which is a relatively smaller value than the overall reported Si-based device’s EOT. This finding successfully illustrates that the transferred electrode/dielectric layer’s mild contact can balance the scaling of the gate dielectric layer with a minimal leakage current and constantly reduce the EOT. Our enhanced electrode/dielectric contact approach provides a straightforward and effective pathway for further scaling of devices in integrated circuits and significantly decreases the overall integrated circuit’s static power consumption (ICs). [ABSTRACT FROM AUTHOR]

This article highlights the preparation of NiFe2O4 nanoparticles by adopting a sol–gel auto-combustion route. The prime focus of this study is to investigate the impact of γ-irradiation on the microstructural, morphological, functional, optical, and magnetic characteristics. The resulting NiFe2O4 products have been characterized employing numerous instrumental techniques such as Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction (XRD), UV–visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), and Physical Properties Measurement System for a variety of γ-ray doses (0, 25, and 100 kGy). FESEM micrographs illustrate the aggregation of ferrite nanoparticles in the pristine NiFe2O4 product having an average particle size of 168 nm, and the surface morphology is altered after exposure to γ-irradiation. XRD spectra have been analyzed employing the Rietveld method, and the results of the XRD investigation reveal the desired phases (cubic spinel phases) of NiFe2O4 with the observation of other transitional phases. The values of the crystallite size are in the range of 34.04–34.71 nm investigated by the Debye–Scherrer (D–S) method. Several microstructural parameters, such as bond length, bond angle, and hopping length, have been determined from the analysis of the Rietveld method. This study reports that γ-irradiations demonstrate a great influence on optical bandgap energy, and it varies from 1.80 to 1.89 eV evaluated via the Kubelka–Munk function. The FTIR measurement depicts a proof for the persistence of Ni–O and Fe–O stretching vibrations within the respective products at positions 365 and 547 cm−1, respectively, thus indicating the successful development of NiFe2O4. The saturation magnetization (MS) of the pristine Ni ferrite product is noticed to be 28.08 emu/g. A considerable increase in MS is observed in the case of low γ-dose (25 kGy), and a decrement nature is disclosed after the result of high dose of γ-irradiation (100 kGy). [ABSTRACT FROM AUTHOR]

With its atomically smooth surface yet no dangling bond, chemical inertness and high temperature sustainability, the insulating hexagonal boron nitride (h-BN) can be an ideal substrate for two-dimensional (2D) material growth and device measurement. In this review, research progress on the chemical growth of 2D materials on h-BN has been summarized, such as chemical vapor deposition and molecular beam epitaxy of graphene and various transition metal dichalcogenides. Further, stacking of the as-grown 2D materials relative to h-BN, thermal expansion matching between the deposited materials and h-BN, electrical property of 2D materials on h-BN have been discussed in detail.