Search

Strong optical confinement and light–matter interaction within semiconductor nanostructures are crucial to modulate the emission property. A fundamental understanding of these interesting phenomena is important to scientific and industrial communities. In this paper, we synthesized the surface oxidized CdS micro/nano-wires by post-oxidation of CdS micro/nano-wires at 475 °C and investigated systematically their novel emission properties. Scanning electron microscopy, energy dispersive x-ray spectrometry, and Raman spectroscopy confirmed the formation of the oxidized surface without changing the structure and morphology of CdS micro/nano-wires greatly. In situ micro-photoluminescence showed the continuous modulation of multi-sub-band emission of both near bandgap and defect state simultaneously with an ultra-broad spectrum range from 490 nm to 750 nm. According to the excitation wavelength-, excitation power-, and temperature-dependent PL spectra, the sub-band near bandgap emission originated from strong light–matter interaction such as photon–exciton coupling, while the whispering gallery mode (WGM) micro-cavity played an important role in the sub-band emission of the defect state. The spatial-resolved mapping of emission modes confirmed the sub-band near bandgap and defect WGM micro-cavity emission from the core and oxidized surface of CdS micro-wires, respectively. The multi-exponential lifetime dynamics further indicated the complex recombination process of both near bandgap and defect state emission. These results are different from the one-step synthesized CdS@CdO core/shell micro-wires and reveal an interesting exciton–photon coupling with enhanced optical cavity confinement in the post-treated CdS micro/nano-wires, representing the rational tailoring of surface/interface relevant properties to control the light emission for application in nanophotonic devices.

High purity and tin-doped 1D CdS micro/nano-structures were synthesized by a convenient thermal evaporation method. SEM, EDS, XRD and TEM were used to examine the morphology, composition, phase structure and crystallinity of as-prepared samples. Raman spectrum was used to confirm tin doped into CdS effectively. The effect of impurity on the photoresponse properties of photodetectors made from these as-prepared pure and tin-doped CdS micro/nano-structures under excitation of light with different wavelength was investigated. Various photoconductive parameters such as responsivity, external quantum efficiency, response time and stability were analyzed to evaluate the advantage of doped nanowires and the feasibility for photodetector application. Comparison with pure CdS nanobelt, the tin-doped CdS nanowires response to broader spectral range while keep the excellect photoconductive parameters. Both trapped state induced by tin impurity and optical whispering gallery mode microcavity effect in the doped CdS nanowires contribute to the broader spectral response. The micro-photoluminescence was used to confirm the whispering gallery mode effect and deep trapped state in the doped CdS nanowires.

In the two-terminal Au/WO3 nanowire/Au electronic device with two Schottky barriers, drifting of oxygen vacancies under strong electric field induced by the bias voltage applied at short distance will result in the effective width of the reverse biased Schottky barrier decreasing, and then result in the memristive effect or resistive switching phenomenon. By unidirectional bias voltage sweeping, the Au/WO3 Schottky contact can be turned gradually and reversibly into Ohmic contact, and then the two-terminal Au/WO3 nanowire/Au resistive switching device can be reconfigured gradually and reversibly from non-rectifying state to either a forward or reverse rectifying state.