Electrical and photoresponse properties of an intramolecular p-n homojunction in single phosphorus-doped ZnO nanowires.

The single-crystal n-type and p-type ZnO nanowires (NWs) were synthesized via a chemical vapor deposition method, where phosphorus pentoxide was used as the dopant source. The electrical and photoluminescence studies reveal that phosphorus-doped ZnO NWs (ZnO:P NWs) can be changed from n-type to p-type with increasing P concentration. Furthermore, we report for the first time the formation of an intramolecular p-n homojunction in a single ZnO:P NW. The p-n junction diode has a high on/off current ratio of 2.5 x 10(3) and a low forward turn-on voltage of approximately 1.37 V. Finally, the photoresponse properties of the diode were investigated under UV (325 nm) excitation in air at room temperature. The high photocurrent/dark current ratio (3.2 x 10(4)) reveals that the diode has a potential as extreme sensitive UV photodetectors.

Reconfigurable metasurfaces that enable light polarization control by light.

Plasmonic metasurfaces have recently attracted much attention because of their novel characteristics with respect to light polarization and wave front control on deep-subwavelength scales. The development of metasurfaces with reconfigurable optical responses is opening new opportunities in high-capacity communications, real-time holograms and adaptive optics. Such tunable devices have been developed in the mid-infrared spectral range and operated in light intensity modulation schemes. Here we present a novel optically reconfigurable hybrid metasurface that enables polarization tuning at optical frequencies. The functionality of tuning is realized by switching the coupling conditions between the plasmonic modes and the binary isomeric states of an ethyl red switching layer upon light stimulation. We achieved more than 20° nonlinear changes in the transmitted polarization azimuth using just 4 mW of switching light power. Such design schemes and principles could be easily applied to dynamically adjust the functionalities of other metasurfaces.

The relationship between quantum transport and microstructure evolution in carbon-sheathed Pt granular metal nanowires.

The carbon-sheathed Pt nanowires fabricated by focused ion beam induced deposition were Pt grains in a Ga-doped carbon matrix. The dimensions of the Pt quantum dots and the intergrain coupling strength were modified through annealing the nanowires, and therefore our investigation demonstrates a tunable 'quantum metal' system by experiment via adjusting both the effects of electron-electron (e-e) interaction and the quantum interference. At low temperatures, the as-deposited samples display a [Formula: see text] temperature dependence of resistivity, while the 500 °C annealed samples exhibit a ln(T) temperature dependence of conductivity. For the 900 °C annealed samples, the conductivity was enhanced by one order of magnitude, accompanied by a metallic temperature dependence of resistivity and a negative magnetoresistance. The interesting transitions from e-e interactions to local voltage fluctuations, from electron localization to delocalization, from tunneling transport between isolated Pt grains to diffusive transport in continuously conductive metal, and from weak antilocalization with spin-orbital scattering to weak localization, are discussed with reference to the evolution of the sample microstructures. The results and discussions may be valuable for understanding how the microstructures influence the manner of electron transport through controlling the intergrain coupling strength, intragrain confinements, and the degree of disorder.