Nanjing National Laboratory of Microstructures

Nanjing, China

Nanjing National Laboratory of Microstructures

Nanjing, China

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Fu D.,University of California at Berkeley | Fu D.,Nanjing University | Fu D.,Nanjing National Laboratory of Microstructures | Zou J.,University of California at Berkeley | And 7 more authors.
Nano Letters | Year: 2011

Charge transfer, surface/interface, defect states, and internal fields strongly influence carrier statics and dynamics in semiconductor nanowires. These effects are usually probed using spatially resolved scanning current techniques, where charge carriers are driven to move by diffusion force due to a density gradient, drift force due to internal fields, and thermoelectric force due to a temperature gradient. However, in the analysis of experimental data, analytical formulas are usually used which are based on the assumption that a single component of these forces dominates the carrier dynamics. In this work we show that this simplification is generally not justified even in the simplest configurations, and the scanning microscopy data need to be analyzed with caution. We performed a comprehensive numerical modeling of the electrothermal dynamics of free charge carriers in the scanning photocurrent microscopy configuration. The simulation allows us to reveal and predict important, surprising effects that are previously not recognized, and assess the limitation as well as potential of these scanning current techniques in nanowire characterization. © 2011 American Chemical Society.


Li M.,Nanjing National Laboratory of Microstructures | Zhang R.,Nanjing National Laboratory of Microstructures | Zhang Z.,Nanjing National Laboratory of Microstructures | Yan W.S.,Nanjing National Laboratory of Microstructures | And 6 more authors.
Superlattices and Microstructures | Year: 2010

By solving Schrödinger and Poisson equations self-consistently for AlxGa1-xN/GaN heterostructures grown along the c axis, the spatial distribution of electrons and the energy of all the bound states confined in heterostructures are obtained, and electrons are found to occupy the first two subbands. Considerable magnitude of the Rashba spin splitting for the first two subbands at the Fermi level is obtained. Changes of the Rashba spin splitting with the Al composition in the barrier are calculated. The effect of electrons taking up more than one subband on the Rashba spin splitting for the first subband is discussed. Individual factors contributing to the Rashba spin splitting are discussed in detail, and the contribution to the Rashba coefficient from the well and the heterointerface are found to be much more than that from the barrier. The results show that a high density of the 2DEG and the internal electric field caused by the piezoelectric polarization and the spontaneous polarization are crucial for considerable Rashba spin splitting for AlxGa1-xN/GaN heterostructures. © 2010 Elsevier Ltd. All rights reserved.


Zhang X.,Nanjing National Laboratory of Microstructures | Zhang X.,Gannan Normal University | Xu Z.,Nanjing National Laboratory of Microstructures | Tang S.,Nanjing National Laboratory of Microstructures | And 2 more authors.
Crystal Growth and Design | Year: 2011

Single-crystalline alkaline-earth metal manganites CaMn3O 6, SrMn3O6-x and Ba6Mn 24O48 nanoribbons have been successfully synthesized by a facile ion-exchange approach based on molten-salt reaction between Na 0.44MnO2 nanoribbons and CaCl2, SrCl 2, and BaCl2. All of these as-prepared nanoribbons are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). Taking the synthesis of single-crystalline SrMn3O6-x nanoribbons as an example, we researched in detail the conversion process from Na0.44MnO2 nanoribbons to SrMn3O6-x nanoribbons. Our results indicate that Na0.44MnO2 nanoribbons serve as the precursor template and the final products are obtained via ion-exchange reaction. Although there is a complete cation exchange, a change in stoichiometry, and a change in crystal structure, the morphology is nearly perfectly maintained. The synthetic method is thought to be a self-sacrificing templating route. © 2011 American Chemical Society.


Lan C.,Nanjing National Laboratory of Microstructures | Gong J.,Nanjing National Laboratory of Microstructures | Gong J.,Hohai University | Wang Z.,Nanjing National Laboratory of Microstructures | Yang S.,Nanjing National Laboratory of Microstructures
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2011

The synthesis of single crystalline K6Ta10.8O 30 nanowires by molten salt method was reported for the first time. X-ray diffraction results indicated that the as-prepared products were pure phase K6Ta10.8O30. Scanning electron microscopy and transmission electron microscopy results showed that the products consisted of wire-like nanostructures with 100-300 nm in diameter and several micrometers in length. High resolution electron microscopy and selected area electron diffraction results indicated that the K6Ta10.8O 30 nanowires were single crystalline with a growth direction of [0 0 1]. The ultraviolet-visible diffuse reflectance measurement showed that the band gap of the nanowires was about 4.1 eV. The effects of reaction temperature, time, and weight ratio of the precursor (mixture of K2CO3 and Ta2O5) to KCl salt on the morphology of the products were investigated. © 2011 Elsevier B.V. All rights reserved.


Hu Y.C.,Nanjing National Laboratory of Microstructures | Ji Q.,Nanjing National Laboratory of Microstructures | Ge J.J.,Nanjing National Laboratory of Microstructures | Xie R.B.,Nanjing National Laboratory of Microstructures | And 5 more authors.
Journal of Alloys and Compounds | Year: 2010

The structure and photo-doping effect on Sr2FeMoO6 are investigated using the X-ray powder diffraction and positrons annihilation technique, respectively. Anti-site defect is about 8.8%, can be estimated directly from the XRD pattern, which is well consistent with that of obtained from the XRD refinements. The integral intensity ratio of the reflection (1 0 1) and the reflections (2 0 0) and (1 1 2) may used to estimate the concentration of the anti-site defect. The positron annihilation lifetime in Sr2FeMoO6 is sensitive to photo-doping. The average lifetime and the electron density ne vary with photo-doping. © 2009.


Fu D.,University of California at Berkeley | Fu D.,Nanjing University | Fu D.,Nanjing National Laboratory of Microstructures | Levander A.X.,University of California at Berkeley | And 6 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We report an effect that occurs in semiconductors where internal electrical fields interact with a temperature gradient. Steady current vortices and a magnetic field develop in the system, even without external carrier injection. The effect is electrodynamic, energy dissipative, and fundamentally distinct from any previously described electrothermal effects. In bipolar structures the effective thermopower can be significantly modified by the vortices. Joule heating arising from the vortices reduces the thermal conductivity by an amount comparable to the electronic thermal conductivity. © 2011 American Physical Society.


Deng Y.,Nanjing University | Deng Y.,Nanjing National Laboratory of Microstructures | Zhou J.,Nanjing University of Aeronautics and Astronautics | Wu D.,Nanjing National Laboratory of Microstructures | And 2 more authors.
Japanese Journal of Applied Physics | Year: 2012

Featherlike (CoFe2O4)0.3-(BaTiO 3)0.7 (CFO-BTO) nanostructures were synthesized by a hydrothermal reaction and polymer-assisted deposition. With CFO nanopillars embedded in the BTO matrix, the nanostructures show an average diameter of 250nm and lengths of up to 5 μm. The microstructure and growth mechanism of the nanostructures were investigated. A large magnetoelectric (ME) coefficient of 51.8mVcm-1 Oe-1 at room temperature and a strong phonon abnormality between 110 and 140 °C are discussed. # 2012 The Japan Society of Applied Physics. © 2012 The Japan Society of Applied Physics.


Zhang X.,Nanjing National Laboratory of Microstructures | Tang S.,Nanjing National Laboratory of Microstructures | Li Y.,Nanjing National Laboratory of Microstructures | Du Y.,Nanjing National Laboratory of Microstructures
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2010

Single crystalline Ba6Mn24O48 nanoribbons with diameters ranging from one hundred nanometers to a few hundred nanometers and length up to tens of microns are synthesized via a facile molten salt method. These nanoribbons are characterized by a range of methods including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The magnetic properties of Ba6Mn24O48 nanoribbons are investigated by the zero-field-cooled (ZFC), field-cooled (FC) magnetization, and ac susceptibility. Upon cooling, we find the reentrant spin glass (RSG) behavior in these nanoribbons, i.e., paramagnetic (PM), antiferromagnetic (AFM), and spin glass (SG). The RSG behavior might be due to the surface spin disorder, geometrical frustration and Mn3+/Mn4+ mixture in Ba6Mn24O48 nanoribbons. Crown Copyright © 2010.


Xu J.,Nanjing National Laboratory of Microstructures | Chen G.,Nanjing National Laboratory of Microstructures | Song C.,Nanjing National Laboratory of Microstructures | Chen K.,Nanjing National Laboratory of Microstructures | And 2 more authors.
Applied Surface Science | Year: 2010

Laser induced crystallization of ultrathin hydrogenated amorphous Si films or amorphous Si-based multilayered structures were used to get high density Si nanodots. The present technique can get size controllable Si nanodots embedded in various dielectric materials with uniform distribution which was revealed by cross-section transmission electron microscopy. Room temperature photoluminescence and electroluminescence were achieved with the emission wavelength in a visible light region both from a-SiN/Si nanodots/a-SiN sandwiched and Si nanodots/SiO2 multilayered structures. The luminescence was associated with the radiative recombination of generated electron-hole pairs in Si nanodots or the luminescent surface states. The electroluminescence intensity is increased with increasing the injection current implying the bipolar carrier injection plays an important role in enhancing the luminescence efficiency. The formed Si nanodots by the present approach can be applied for many kinds of devices such as high efficient light emitting diodes and solar cells. © 2010 Elsevier B.V. All rights reserved.


PubMed | Nanjing National Laboratory of Microstructures
Type: Journal Article | Journal: Chemical communications (Cambridge, England) | Year: 2011

The synthesis of a novel aza-BODIPY dye functionalized with fused pyrazine rings, suitable for use as a selective colorimetric and fluorometric sensor for NH(4)(+), is outlined. In addition to significant fluorescence quenching, an obvious colorimetric change from green to red-pink is observed enabling facile naked-eye detection of NH(4)(+).

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