Controlled Synthesis, Property Modulation Of Zinc-based Semiconductor Nanomaterials

For the research on nanomaterials,controlled morphology and modulated performance are attracting extensive interest.The cadmium or magnesium-doped zinc oxide nano--materials prepared by a simple,energy-saving and fast low-temperature combustion method.The introduction of the dopants into ZnO hosts can control the growth and modulate its optical properties.The results will offer a significant help for nanophotonic device applications based on ZnO materials in the future.The main results are as follows:1.The curled(ZnCd)O ribbons were prepared by a low-temperature combustion approach.The lattice distortion,originating from the introduction of Cd into ZnO, makes the non-polar E₂^high Raman scattering mode blueshift.Due to the formation of a deeper level,an orange emission appears at about 600nm in 5%Cd doped-ZnO annealed at 600℃.As the 5%Cd-doped sample annealed at 1000℃,Cd can precipitate from the host and form Zn-doped CdO,resulting into two band edge emission and a predominant green emission of 525nm related to CdO band edge emission Regardless of the Cd content and the annealing temperature,the UV emission does not exhibit obvious redshift.2.The curled(ZnMg)O sheets were also prepared by a low-temperature combustion approach.As Mg concentration increases,it can precipitate and form Zn-doped MgO with a broader band gap,wrapped Mg-doped ZnO outside.Thus,the near-band-edge emission of Mg-doped ZnO is enhanced greatly due to quantum confinement effect.The emission intensity ratio of the NBE to green increases with increase the excitation power density,indicating that the green emission could originate from the transition from a shallow donor level to Vo^<sup>++.The high concentration Mg can leads to a significant blueshift of ZnO NBE emission due to alloy effects.3.Silica coated zinc sulfide nanospheres are successfully synthesized by a simple thermal evaporation method in the tube furnace.The core is mainly a hollow structure by the analysis of TEM.In the nanosphere cores,however,there exsit some ZnS naoparties and nanorods which were not decomposed,resulting into an existence of 460nm light-emitting from ZnS defects.Due to the existence of smaller amorphous Si,a strong orange emission exists in photoluminescence,originating from the band edge emission of Si.