Synthesis And Characterization Of CdS Superlattice Nanowire And Ultra-long Carbon Wire

CdS has attractive optical and photoelectric characteristics with potential applicationvalues in a wide range fields. Sn-based CdS superlattice nanowire is synthesized by asimple CVD method. Using element mapping and EDS measurement, we think as-grownnanowire has CdS shell and intermittent distribution of Sn inside as core. In order toinvestigate the PL spectrum and optical characterization, excitation wavelength、temperature and other facters are used. The existence of Sn compress lattice of CdS,resulting in increase of band gap and blue shift of PL especially in low temperature. At thesurface of nanowire, emission from band gap is higher than bound surface states whileopposite is happening inner the nanowire. Besides, emission of deep-level that associatedwith bound surface states is mainly determined by surface crystallinity. With the increase oflaser power, emission of bound surface states is saturated soon and band-gap emissionincrease a lot. CdS lasing is realized due to inner F-P cavity, which proves potentialapplication of as-grown nanowire in making nano-laser.Ultra-long straight carbon wires of few microns in diameter and centimeters in lengthare synthesized in large scale through a controllable and simple one-step chemical vapordeposition (CVD) method. These carbon wires grow in direction parallel to the gas flow inCVD with radio of axial length to diameter more than1000:1. Scanning electronmicroscope, transmission electron microscopy and energy dispersive spectroscopy areinvestigated to confirm the structure and morphology of the as-obtained carbon wires.Room temperature Raman spectrum and XRD was also investigated. Si is proved to act asthe catalyst of as-grown carbon wires. I-V curves were measured, which show potentialapplication in micro-electric devices.