RESUMEN
Two-dimensional (2D) semiconductors have generated considerable attention for high-performance electronics and optoelectronics. However, to date, it is still challenging to mechanically exfoliate large-area and continuous monolayers while retaining their intrinsic properties. Here, we report a simple dry exfoliation approach to produce large-scale and continuous 2D monolayers by using a Ag film as the peeling tape. Importantly, the conducting Ag layer could be converted into AgOx nanoparticles at low annealing temperature, directly decoupling the conducting Ag with the underlayer 2D monolayers without involving any solution or etching process. Electrical characterization of the monolayer MoS2 transistor shows a decent carrier mobility of 42 cm2 V-1 s-1 and on-state current of 142 µA/µm. Finally, a plasmonic enhancement photodetector could be simultaneously realized due to the direct formation of Ag nanoparticles arrays on MoS2 monolayers, without complex approaches for nanoparticle synthesis and integration processes, demonstrating photoresponsivity and detectivity of 6.3 × 105 A/W and 2.3 × 1013 Jones, respectively.
RESUMEN
Vertical field effect transistors (VFETs) have attracted considerable interest for developing ultra-scaled devices. In particular, individual VFET can be stacked on top of another and does not consume additional chip footprint beyond what is needed for a single device at the bottom, representing another dimension for high-density transistors. However, high-density VFETs with small pitch size are difficult to fabricate and is largely limited by the trade-offs between drain thickness and its conductivity. Here, a simple approach is reported to scale the drain to sub-10 nm. By combining 7 nm thick Au with monolayer graphene, the hybrid drain demonstrates metallic behavior with low sheet resistance of ≈100 Ω sq-1 . By van der Waals laminating the hybrid drain on top of 3 nm thick channel and scaling gate stack, the total VFET pitch size down to 20 nm and demonstrates a higher on-state current of 730 A cm-2 . Furthermore, three individual VFETs together are vertically stacked within a vertical distance of 59 nm, representing the record low pitch size for vertical transistors. The method pushes the scaling limit and pitch size limit of VFET, opening up a new pathway for high-density vertical transistors and integrated circuits.
RESUMEN
Perovskite heterojunctions are essential components of perovskite optoelectronics, but their construction and investigation have been impeded by the instability and severe anion interdiffusion. This work epitaxially deposits p-type CsPbBr3 on n-type Nb:SrTiO3 (STO) to construct a functional perovskite heterojunction with high stability. The lattice match allows epitaxial growth of CsPbBr3 to occur over large scale, resulting in a monocrystalline thin film with excellent crystallinity and uniformity. The highly stable STO prevents the anion migration frequently happening in halide perovskites, forming a sharp interface of two perovskite with opposite conduction type, with which a diode is fabricated and a current rectification ratio of 374 is obtained. The diode is able to work as a photodetector with dark current of 2.01 × 10-12 A at -1 V and responsivity (R) of 8.26 A W-1 , rendering a detectivity (D*) of 2.98 × 1013 Jones. Owing to the all-inorganic architecture, effective photoresponse at temperature as high as 150 °C is guaranteed with D* of ≈1.52 × 1013 Jones. Combining the unique optoelectrical properties of halide perovskite and the rigidity of oxide perovskite, the epitaxy of CsPbBr3 on n-type STO opens up a new method to construct functional perovskite heterojunction for optoelectronics.
RESUMEN
A method was developed for the simultaneous determination of 14 fat-soluble dyes in chilli products. The samples were extracted with hexane/acetone. The cleanup was performed with gel permeation chromatography (GPC) cleanup system. A HPLC separation was performed using variable wavelength detector and a gradient elution with 0.1% formic acid and methanol-acetonitrile (1:1, v/v) as the mobile phases. Good linearity (R² ≥ 0.995) was observed between 0.1 and 5.0 µg/mL. Detection limits of the investigated dyes, which were evaluated at signal to noise ratio of 3, were in the ranges of 11-71 µg/kg. The recoveries of the 14 synthetic colourants in three matrices ranged from 73.4% to 103.5%. Relative standard deviations ranged from 3.7% to 12.3%. The method has been successfully used for the determination of banned dyes in real samples.
