多铁性纳米点结构及微纳器件应用

在当前电子技术微型化和高度集成化的趋势下,多铁性纳米材料的研究正逐渐成为一个重要主题。这方面的研究还处在起步阶段,在材料的制备工艺和表征手段方面还面临诸多挑战。文章简要介绍了多铁性纳米点的制备工艺(包括离子刻蚀、自组构、多孔氧化铝模板方法等)和以多功能扫描探针为代表的表征手段,还介绍了纳米点带来的新颖的物理现象及其在微纳器件应用等方面的研究进展。

1.46 μm room-temperature emission from InAs/InGaAs quantum dot nanostructures

We present a study on InAs/InGaAs QDs nanostructures grown by molecular beam epitaxy on InGaAs metamorphic buffers, that are designed so as to determine the strain of QD and, then, to shift the luminescence emission towards the 1.5 μm region （QD strain engineering）. Moreover, we embed the QDs in InAIAs or GaAs barriers in addition to the InGaAs confining layers, in order to increase the activation energy for confined carrier thermal escape; thus, we reduce the thermal quenching of the photoluminescence, which prevents room temperature emission in the long wavelength range. We study the dependence of QD properties, such as emission energy and activation energy, on barrier thickness and height and we discuss how it is possible to compensate for the barrier-induced QD emission blue-shift taking advantage of QD strain engineering. Furthermore, the combination of enhanced barriers and QD strain engineering in such metamorphic QD nanostmctures allowed us to obtain room temperature emission up to 1.46μm, thus proving how this is a valuable approach in the auest for 1.55 um room temperature emission from ODs grown on GaAs substrates.

Ferroxidase-like activity of Au nanorod/Pt nanodot structures and implications for cellular oxidative stress

Platinum nanoparticles （NPs） are reported to mimic various anfioxidant enzymes and thus may produce a positive biological effect by reducing reactive oxygen species （ROS） levels. In this manuscript, we report Pt NPs as an enzyme mimic of ferroxidase by depositing platinum nanodots on gold nanorods （Au@Pt NDRs）. Au@Pt NDRs show pH-dependent ferroxidase-like activity and have higher activity at neutral pH values. Cytotoxicity results with human cell lines （lung adenocarcinoma A549 and normal bronchial epithelial cell line HBE） show that Au@Pt NDRs are taken up into cells via endocytosis and translocate into the endosome/lysosome. Au@Pt NDRs have good biocompatibility at NDR particle concentrations lower than 0.15 nM. However, in the presence of H202, lysosome- located NDRs exhibit peroxidase-like activity and therefore increase cytotoxicity. In the presence of FeE＋, the ferroxidase-like activity of the NDRs protects cells from oxidative stress by consuming H202. Thorough consideration should be given to this behavior when employinK Au@Pt NDRs in biological svstems.

Bi2WO6 quantum dot-intercalated ultrathin montmo- rillonite nanostructure and its enhanced photocatalytic performance

The kinetic competition between electron-hole recombination and water oxidation is a key limitation for the development of efficient solar water splitting materials. In this study, we present a solution for solving this challenge by constructing a quantum dot-intercalated nanostructure. For the first time, we show the interlayer charge of the intercalated nanostructure can significantly inhibit the electron-hole recombination in photocatalysis. For Bi2WO6 quantum dots （QDs） intercalated in a montmorillonite （MMT） nanostructure as an example, the average lifetime of the photogenerated charge carriers was increased from 3.06 μs to 18.8 Ds by constructing the intercalated nanostructure. The increased lifetime markedly improved the photocatalytic performance of Bi2WO6 both in solar water oxidation and environmental purification. This work not oMy provides a method to produce QD-intercalated ultrathin nanostructures but also a general route to design efficient semiconductor-based photoconversion materials for solar fuel generation and environmental purification.

Advanced 3D nanohybrid foam based on graphene oxide: Facile fabrication strategy, interfacial synergetic mechanism, and excellent photocatalytic performance

Herein,a unique nanohybrid foam was fabricated with titanium dioxide(TiO2)-carbon quantum dots(CQDs)nanoparticles intercalated between graphene oxide(GO)layers via a facile and low-cost solvothermal method.Compared with pure GO foam,the fabricated GO-TiO2-CQDs foam displayed high degradation rate towards methyl orange(MO),methylene blue(MB),and rhodamine B(Rh B),respectively,under the Xenon lamp irradiation.The composite foam can be used for several times and remain a high degradation rate without structural damage.The photochemical property was attributed to the 3D porous structure of GOTiO2-CQDs foam,in which ultrafine hydrogenated TiO2-CQDs nanoparticles were densely anchored on the GO sheets.This paper provides an efficient strategy to tune the charge transport and thus enhance the photocatalytic performance by combining the semi-conductive GO and quantum dots.

Enhanced Cross-Phase Modulation via Phase Control in a Quantum dot Nanostructure

A four-level quantum dot (QD) nanostructure interacting with four fields (two weak near-infrared (NIR) pulses and two control fields) forms the well-known double-cascade configuration.We investigate the cross-phase modulation (XPM) between the two NIR pulses.The results show,in such a closed-loop scheme,that the XPM can be greatly enhanced,while the linear absorption and two-photon absorption (gain) can be efficiently depressed by tuning the relative phase among the applied fields.This protocol may have potential applications in NIR all-optical switch design and quantum information processing with the solid-state materials.