High-Performance Self-Powered UV Detector Based on SnO-TiO Nanomace Arrays.

Photoelectrochemical cell-typed self-powered UV detectors have attracted intensive research interest due to their low cost, simple fabrication process, and fast response. In this paper, SnO-TiO nanomace arrays composed of SnO nanotube trunk and TiO nanobranches were prepared using soft chemical methods, and an environment-friendly self-powered UV photodetector using this nanostructure as the photoanode was assembled. Due to the synergistic effect of greatly accelerated electron-hole separation, enhanced surface area, and reduced charge recombination provided by SnO-TiO nanomace array, the nanostructured detector displays an excellent performance over that based on bare SnO arrays.

Electrically tunable tunneling rectification magnetoresistance in magnetic tunneling junctions with asymmetric barriers.

The development of multifunctional spintronic devices requires simultaneous control of multiple degrees of freedom of electrons, such as charge, spin and orbit, and especially a new physical functionality can be realized by combining two or more different physical mechanisms in one specific device. Here, we report the realization of novel tunneling rectification magnetoresistance (TRMR), where the charge-related rectification and spin-dependent tunneling magnetoresistance are integrated in Co/CoO-ZnO/Co magnetic tunneling junctions with asymmetric tunneling barriers. Moreover, by simultaneously applying direct current and alternating current to the devices, the TRMR has been remarkably tuned in the range from -300% to 2200% at low temperature.

Reversible control of the magnetization of spinel ferrites based electrodes by lithium-ion migration.

Lithium-ion (Li-ion) batteries based on spinel transition-metal oxide electrodes have exhibited excellent electrochemical performance. The reversible intercalation/deintercalation of Li-ions in spinel materials enables not only energy storage but also nondestructive control of the electrodes' physical properties. This feature will benefit the fabrication of novel Li-ion controlled electronic devices.

Ultrabroadband MoS Photodetector with Spectral Response from 445 to 2717 nm.

Photodetectors with excellent detecting properties over a broad spectral range have advantages for the application in many optoelectronic devices. Introducing imperfections to the atomic lattices in semiconductors is a significant way for tuning the bandgap and achieving broadband response, but the imperfection may renovate their intrinsic properties far from the desire. Here, by controlling the deviation from the perfection of the atomic lattice, ultrabroadband multilayer MoS photodetectors are originally designed and realized with the detection range over 2000 nm from 445 nm (blue) to 2717 nm (mid-infrared).

Broadband atomic-layer MoS optical modulators for ultrafast pulse generations in the visible range.

Visible lasers are a fascinating regime, and their significance is illustrated by the 2014 Noble prizes in physics and chemistry. With the development of blue laser diodes (LDs), the LD-pumped solid-state visible lasers become a burgeoning direction today. Constrained by the scarce visible optical modulators, the solid-state ultrafast visible lasers are rarely realized.

High-Performance Self-powered Photodetectors Based on ZnO/ZnS Core-Shell Nanorod Arrays.

In recent years, there is an urgent demand for high-performance ultraviolet photodetectors with high photosensitivity, fast responsivity, and excellent spectral selectivity. In this letter, we report a self-powered photoelectrochemical cell-type UV detector using the ZnO/ZnS core-shell nanorod array as the active photoanode and deionized water as the electrolyte. This photodetector demonstrates an excellent spectral selectivity and a rapid photoresponse time of about 0.

Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions.

Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current voltage, and this rectification voltage strongly varies with the external magnetic field. We find that the rectification magnetoresistance in Al/Ge Schottky heterojunctions is as large as 250% at room temperature, which is greatly enhanced as compared with the conventional magnetoresistance of 70%.

Atomic-layer molybdenum sulfide optical modulator for visible coherent light.

Coherent light sources in the visible range are playing important roles in our daily life and modern technology, since about 50% of the capability of the our human brains is devoted to processing visual information. Visible lasers can be achieved by nonlinear optical process of infrared lasers and direct lasing of gain materials, and the latter has advantages in the aspects of compactness, efficiency, simplicity, etc. However, due to lack of visible optical modulators, the directly generated visible lasers with only a gain material are constrained in continuous-wave operation.

Passively Q-switched nanosecond erbium-doped fiber laser with MoS(2) saturable absorber.

Passively Q-switched nanosecond pulsed erbium-doped fiber laser based on MoS(2) saturable absorber (SA) is experimentally demonstrated. The high quality MoS(2) SA deposited on the broadband high-reflectivity mirror with a large modulation depth of 9% was prepared by pulsed laser deposition method. By inserting the MoS(2) SA into an erbium-doped fiber laser, stable Q-switched operation can be achieved with the shortest pulse width of 660 ns, the maximum pulse energy up to 152 nJ and pulse repetition rates varying from 116 to 131 kHz.

Electrical control of memristance and magnetoresistance in oxide magnetic tunnel junctions.

Electric-field control of magnetic and transport properties of magnetic tunnel junctions has promising applications in spintronics. Here, we experimentally demonstrate a reversible electrical manipulation of memristance, magnetoresistance, and exchange bias in Co/CoO-ZnO/Co magnetic tunnel junctions, which enables the realization of four nonvolatile resistance states. Moreover, greatly enhanced tunneling magnetoresistance of 68% was observed due to the enhanced spin polarization of the bottom Co/CoO interface.

A high performance quasi-solid-state self-powered UV photodetector based on TiO2 nanorod arrays.

Self-powered UV photodetectors based on TiO2 and ZnO nanorod arrays have attracted lots of attention in recent years due to their various advantages. Impressive performances were observed in photochemical cell based UV detectors. However, liquid electrolytes are not ideal for long-term operation and are inconvenient for practical applications.

Broadband few-layer MoS2 saturable absorbers.

The bandgaps of monolayer and bulk molybdenum sulfide (MoS2 ) result in that they are far from suitable for application as a saturable absorption device. In this paper, the operation of a broadband MoS2 saturable absorber is demonstrated by the introduction of suitable defects. It is believed that the results provide some inspiration in the investigation of two-dimensional optoelectronic materials.

ZnO nanosheet arrays constructed on weaved titanium wire for CdS-sensitized solar cells.

Ordered ZnO nanosheet arrays were grown on weaved titanium wires by a low-temperature hydrothermal method. CdS nanoparticles were deposited onto the ZnO nanosheet arrays using the successive ionic layer adsorption and reaction method to make a photoanode. Nanoparticle-sensitized solar cells were assembled using these CdS/ZnO nanostructured photoanodes, and their photovoltaic performance was studied systematically.

CdS quantum dot-sensitized solar cells based on nano-branched TiO2 arrays.

Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically.

Spin memristive magnetic tunnel junctions with CoO-ZnO nano composite barrier.

The spin memristive devices combining memristance and tunneling magnetoresistance have promising applications in multibit nonvolatile data storage and artificial neuronal computing. However, it is a great challenge for simultaneous realization of large memristance and magnetoresistance in one nanoscale junction, because it is very hard to find a proper spacer layer which not only serves as good insulating layer for tunneling magnetoresistance but also easily switches between high and low resistance states under electrical field. Here we firstly propose to use nanon composite barrier layers of CoO-ZnO to fabricate the spin memristive Co/CoO-ZnO/Co magnetic tunnel junctions.

High-performance self-powered UV photodetectors based on TiO2 nano-branched arrays.

Nano-branched TiO2 arrays were fabricated on fluorine-doped tin oxide (FTO) glass by a facile two-step chemical synthesis process. Self-powered UV photodetectors based on photoelectrochemical cells (PECs) were assembled using these TiO2 nano-branched arrays as photoanodes. These visible-blind self-powered UV photodetectors exhibit high sensitivity and high-speed photoresponse.

ZnO nanoneedle/H2O solid-liquid heterojunction-based self-powered ultraviolet detector.

ZnO nanoneedle arrays were grown vertically on a fluorine-doped tin oxide-coated glass by hydrothermal method at a relatively low temperature. A self-powered photoelectrochemical cell-type UV detector was fabricated using the ZnO nanoneedles as the active photoanode and H2O as the electrolyte. This solid-liquid heterojunction offers an enlarged ZnO/water contact area and a direct pathway for electron transport simultaneously.

A self-powered UV photodetector based on TiO2 nanorod arrays.

Large-area vertical rutile TiO2 nanorod arrays (TNAs) were grown on F/SnO2 conductive glass using a hydrothermal method at low temperature. A self-powered ultraviolet (UV) photodetector based on TiO2 nanorod/water solid-liquid heterojunction is designed and fabricated. These nanorods offer an enlarged TiO2/water contact area and a direct pathway for electron transport simultaneously.

Room temperature ferromagnetism in epitaxial In₂O₃ films with embedded nano-sized Fe₃O₄ columns.

Epitaxial In2O3 films with embedded Fe3O4 oriented nanocolumns were deposited by pulsed laser deposition (PLD) on Y-stabilized ZrO2 (111) substrates. The resulting films show ferromagnetism at room temperature with strong magnetic anisotropy, which can be attributed to the presence of Fe3O4 nanocolumns. Magnetotransport measurements demonstrate a transition from negative magnetoresistance to positive magnetoresistance as the measuring temperature increases.

Annealing effect on Sb2S3-TiO2 nanostructures for solar cell applications.

Nanostructures composited of vertical rutile TiO2 nanorod arrays and Sb2S3 nanoparticles were prepared on an F:SnO2 conductive glass by hydrothermal method and successive ionic layer adsorption and reaction method at low temperature. Sb2S3-sensitized TiO2 nanorod solar cells were assembled using the Sb2S3-TiO2 nanostructure as the photoanode and a polysulfide solution as an electrolyte. Annealing effects on the optical and photovoltaic properties of Sb2S3-TiO2 nanostructure were studied systematically.

Efficient PbS/CdS co-sensitized solar cells based on TiO2 nanorod arrays.

Narrow bandgap PbS nanoparticles, which may expand the light absorption range to the near-infrared region, were deposited on TiO2 nanorod arrays by successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The thicknesses of PbS nanoparticles were optimized to enhance the photovoltaic performance of PbS QDSCs. A uniform CdS layer was directly coated on previously grown PbS-TiO2 photoanode to protect the PbS from the chemical attack of polysulfide electrolytes.

Effects of Sn doping on the morphology and properties of Fe-doped In2O3 epitaxial films.

(Sn, Fe)-codoped In2O3 epitaxial films were deposited on (111)-oriented Y-stabilized ZrO2 substrates by pulsed laser deposition with constant Fe concentration and different Sn concentrations. The influence of Sn concentration on the crystal structure and properties of Fe-doped In2O3 ferromagnetic semiconductor films has been investigated systematically. Experimental results indicate that Sn doping can effectively reduce the surface roughness and suppresses breakup of the films into separated islands.

Effect of native defects and Co doping on ferromagnetism in HfO2: first-principles calculations.

First-principles calculations of undoped HfO(2) and cobalt-doped HfO(2) have been carried out to study the magnetic properties of the dielectric material. In contrast to previous reports, it was found that the native defects in HfO(2) could not induce strong ferromagnetism. However, the cobalt substituting hafnium is the most stable defect under oxidation condition, and the ferromagnetic (FM) coupling between the cobalt substitutions is favorable in various configurations.

Orientation-selective unzipping of carbon nanotubes.

We carried out first-principles calculations to explore the oxidative longitudinal unzipping of single-walled carbon nanotubes (SWCNTs) of different diameters and chiralities. We found that the initial attack leading to nanotube unzipping prefers to occur in the middle region for armchair tubes, and at the tube ends for zigzag tubes. Once the initial attack has taken place, by overcoming an energy barrier whose value decreases with increasing tube diameter, the subsequent breakage of C-C bonds parallel to the ones broken in the former process is barrierless.

First-principles study of Co-doped single-walled silicon nanotubes.

We performed spin-polarized density functional calculations to study the stable configurations, energetics and electronic structures of Co-doped single-walled silicon nanotubes (CoSi(2)NTs) with the stoichiometry of CoSi(2). We found that the incorporation of Co atoms into the wall of SiNTs not only effectively stabilizes the tubes but also tunes their electronic properties. The formation energies of the CoSi(2)NTs are much lower than those of pristine SiNTs, indicating the plausibility of these tubes.