摘要：Flexible photodetectors have become a focus of current researches because they may offer some unique applications in various new areas that require flexible, lightweight, and mechanical shock-resistive sensing elements. In this work, we designed flexible organic-inorganic hybrid photodetectors on various flexible substrates, including polyethylene terephthalate （PET）, common Sellotape and polydimethylsiloxane （PDMS）, with n-type phenyl-C61-butyric acid methyl ester （PCBM） and p-type pearl-like GaP nanowires （NWs） as the active materials. The as-fabricated hybrid devices exhibited an optimized performance superior to the device made of pristine GaP NWs, with a fast response time （43 ms） and high on/off ratio （-170）. Under different bending conditions, the flexible hybrid photodetectors demonstrated excellent flexibility and electrical stability, which make them very promising for further large-scale, high sensitivity and high speed photodetector applications.

摘要：Strain engineering is a powerful tool to tailor the physical properties of materials coherently stacked in an epitaxial heterostructure. Such an approach, applied to the mature field of planar heteroepitaxy, has yielded a variety of new phenomena and devices. Recently, heteroepitaxial vertically aligned nanocomposites have emerged as alternatives to planar structures. Owing to the peculiar geometry of such nanoarchitectures, efficient strain control can be achieved, opening the way to novel functionalities. In this paper, we report a very large tensile axial strain in epitaxial transition metal nanowires embedded in an oxide matrix. We show that axial strains in excess of 1.5% can be sustained over a large thickness （a few hundred nanometers） in epitaxial nanowires having ultrasmall diameters （-3-6 nm）. The axial strain depends on the diameter of the nanowires, reflecting its epitaxial nature and the balance of interface and elastic energies. Furthermore, it is experimentally shown that such strain is metastable, in agreement with the calculations performed in the framework of the Frenkel-Kontorova model. The diameter dependence and metastability provide effective ways to control the strain, an appealing feature for the design of functional nanoarchitectures.

摘要：Developing low dimensional semiconductors with moderate band gaps,intrinsic ferromagnetism and large magnetic anisotropy energies (MAEs) is very desirable for high-speed nano-spintronic devices,which,however,still remains a big ***,via first principles calculations,a potential route to realize such materials is proposed based on a new class of one-dimensional transition metal (TM) embedded stannaspherene (Sn122-) nanowires [TM2(Sn12)]∞ (TM =Ti-Ni).Three semiconductors with robust ferromagnetism are achieved with TM =V,Cr and Fe,which all exhibit direct or quasi-direct band gaps around 1.0 eV,rendering their great potentials for visible light optoelectronic ***,[Cr2(Sn12)]∞ and [Fe2(Sn12)]∞ are both identified as bipolar magnetic semiconductors (BMS) with valence and conduction band edges spin polarized in the opposite directions,which are promising for realizing switch of carriers' spin orientation by electrical gating,while [V2(Sn12)]∞ exhibits a half semiconductor (HSC) property with valence and conduction band edges spin polarized in the same direction and can be used for spin-polarized carriers ***,sizable MAEs are discovered in these nanowires,which are at least two orders of magnitude larger than those of Fe,Co and Ni bulks and also significantly larger than current ferromagnetic semiconductors.

摘要：A fundamental understanding of the electrochemical reaction process and mechanism of electrodes is very crucial for developing high-performance electrode *** this study,we report the sodium ion storage behavior and mechanism of orthorhombic V_(2)O_(5) single-crystalline nanowires in the voltage window of 1.0–4.0 V(***/Na+).The single-crystalline nanowires exhibit a large irreversible capacity loss during the first discharge/charge cycle,and then show excellent cycling stability in the following *** a current density of 100 mA g^(−1),the nanowires electrode delivers initial discharge/charge capacity of 217/88 mA h g^(−1),corresponding to a Coulombic efficiency of only 40.5%;after 100 cycles,the electrode remains a reversible discharge capacity of 78 mA h g^(−1) with a fading rate of only 0.09%per cycle compared with the 2nd cycle discharge *** sodium ion storage mechanism was investigated,illustrating that the large irreversible capacity loss in the first cycle can be attributed to the initially formed single-crystalline α′-Nax V_(2)O_(5)(0.02<x<0.88),in which sodium ions cannot be electrochemically extracted and the α′-Na0.88 V_(2)O_(5) can reversibly host and release sodium ions via a single-phase(solid solution)reaction,leading to excellent cycling *** Na^(+) diffusion coefficient in α′-Nax V_(2)O_(5) ranges from 10^(−12) to 10^(−11.5) cm^(2) s^(−1) as evaluated by galvanostatic intermittent titration technique(GITT).

摘要：The careful design of nano-architectures and smart hybridization of expected active materials can lead to more advanced properties. Here we have engineered a novel hierarchical branching Cu/Cu2O/CuO heteronanostructure by combining a facile hydrothermal method and subsequent controlled oxidation process. The fine structure and epitaxial relationship between the branches and backbone are investigated by high-resolution transmission electron microscopy. Moreover, the evolution of the branch growth has also been observed during the gradual oxidation of the Cu nanowire surface. The experimental results suggest that the surface oxidation needs to be performed via a two-step exposure process to varying humidity in order to achieve optimized formation of a core-shell structured branching architecture. Finally, a proof-of-concept of the function of such a hierarchical framework as the anode material in lithium-ion batteries is demonstrated. The branching core-shell heterostructure improves battery performance by several means： （i） The epitaxially grown branches provide a high surface area for enhanced electrolyte accessibility and high resistance to volume change induced by Li^＋ intercalation/extraction; （ii） the core-shell structure with its well-defined heterojunction increases the contact area which facilitates effective charge transport during lithiation; （iii） the copper core acts as a current collector as well as providing structural reinforcement.

摘要：A wavelength splitter with ultra-compact and simple structure is proposed and analyzed by using both plane wave expansion （PWE） method and finite difference time domain （FDTD） method. The device is based on directional coupling between two parallel lithium niobate （LiNbO3, LN） nanowire optical waveguides. The wavelength splitter with a coupling region length of 5 um can separate 1.3 um and 1.55 um wavelengths for corresponding outputs with transmittance higher than 97%.

摘要：This review describes work presented in the 2014 inaugural Tsinghua University Press-Springer Nano Research Award lecture, as well as current and future opportunities for nanoscience research at the interface with brain science. First, we briefly summarize some of the considerations and the research journey that has led to our focus on bottom-up nanoscale science and technology. Second, we recapitulate the motivation for and our seminal contributions to nanowire- based nanoscience and technology, including the rational design and synthesis of increasingly complex nanowire structures, and the corresponding broad range of ＂applications＂ enabled by the capability to control structure, com- position and size from the atomic level upwards. Third, we describe in more detail nanowire-based electronic devices as revolutionary tools for brain science, including （i） motivation for nanoelectronics in brain science, （ii） demonstration of nanowire nanoelectronic arrays for high-spatial/high-temporal resolution extracellular recording, （iii） the development of fundamentally-new intracellular nanoelectronic devices that approach the sizes of single ion channels, （iv） the introduction and demonstration of a new paradigm for innervating cell networks with addressable nanoelectronic arrays in three-dimensions. Last, we conclude with a brief discussion of the exciting and potentially transformative advances expected to come from work at the nanoelectronics-brain interface.

摘要：A 25-channel 200 GHz arrayed waveguide grating （AWG） based on Si nanowire wavegnides is designed, simulated and fab- ricated. Transfer function method is used in the simulation and error analysis of AWG with width fluctuations. The 25-channel 200 GHz AWG exhibits central channel insertion loss of 6.7 dB, crosstalk of-13 dB, and central wavelength of 1 560.55 nm. The error analysis can explain the experimental results of 25-channel 200 GHz AWG well. By using deep ul- traviolet lithography （DUV） and inductively coupled plasma etching （ICP） technologies, the devices are fabricated on sili- con-on-insulator （SOI） substrate.

摘要：Further improvement of storage density is a key challenge for the application of phase-change memory(PCM)in storage-class ***,for PCM,storage density improvements include feature size scaling down and multilevel cell(MLC)operation,potentially causing thermal crosstalk issues and phase separation issues,*** address these challenges,we propose a high-aspect-ratio(25:1)lateral nanowire(NW)PCM device with conventional chalcogenide Ge_(2)Sb_(2)Te_(5)(GST-225)to realize stable MLC operations,i.e.,low intra-and inter-cell variability and low resistance drift(coefficient=0.009).The improved MLC performance is attributed to the high aspect ratio,which enables precise control of the amorphous region because of sidewall confinement,as confirmed by transmission electron microscopy *** summary,the NW devices provide guidance for the design of future high-aspect-ratio threedimensional PCM devices with MLC capability.

摘要：A compact bi-directional （BiDi） triplexer using grating-assisted multimode interference （MMI） coupler is proposed based on silicon nanowire *** of the high index contrast between silicon and silicon dioxide, the size of the structure is greatly reduced with a footprint of 2.5×911 （μm）. Asymmetrical ports are introduced in the MMI structure to satisfy the bandwidth requirements of the industrial standards ITU-T G.983.3-dB bandwidths of 100, 22, and 15 nm are obtained for the wavelengths of 1 310, 1 490, and 1 550 nm, respectively. The device can be readily fabricated using a commercial CMOS process.