Study On The Solvothermal Synthesis And Physical Properties Of Low Dimensional Chaleogenides Semiconductor

The aim of this dissertation is to explore synthetic methods for low-dimension semiconducting of chalcogenides besides oxides.The as-prepared nano-materials are characterized and their growth mechanism is also investigated.Meanwhile,we realized to control the morphology of the products and physical properties by adjusting the reaction conditions.The major contents can be summarized as follows:1.One dimensional wurtzite ZnS nanowires were synthesized by using ethylenediamine and distilled water as solvents at low temperature.All the nanowires grow alone [001] direction.Meanwhile, the phase and shape controllable synthesis has been realized by tuning the volume ratio of ethylenediamine and distilled water. The morphology of products changes from nanosheets to nanowires and to nanoparticles finally;and the phase of the products transfers from hexagonal to hexagonal-cubic coexisted and to cubic finally. Based on the experimental results,the role of he solvent and the formation mechanism were discussed and first proposed an new self-catalytic growth mechanism to prepare hexagonal ZnS from cubic ZnS.The optical properties were also investigated.This solvothermal technique could be extended to other â…¡-â…¥ secmiconductor materials.2.A simple solvothermal technique has been developed to synthesize ZnS nanowires doped with Mn. In the experiments, different morphology of ZnS:Mn nanocrystallines were achieved by adjusting the Mn content. In low concentration Mn2+, wurzite ZnS nanorods were synthesized with uniform Mn content; In high concentration Mn2+,wurzite ZnS nanorods and cubic nanoparticles were co existed and Mn content is higher in cubic ZnS than in hexagonal ZnS.A possible formation mechanism for the growth and different Mn2+location in ZnS lattice were discussed. The photoluminescence properties by altering the Mn concentration are also investigated, and the reason for the change are discussed. The Magnetic properties are characterized by ESR spectrum and the results reveals that ZnS:Mn system is not suitable for dilute magnetic semiconductor material.3.A facile chemical route to sizecontrollable high-quality ternary alloyed ZnxCd1-xS nanocrystals in oleic acid via a hot-injection approach. Quantum dots exhibit narrow FWHL and high quantum efficiency. The size of quantum dots are controllable by adjusting the ratio of Zn and Cd.Based on the the results of UV-vis and PL spectrum, the ratio of Zn and Cd instead of quantum size is the key factor to tune the energy bands of ZnCdS.Time-dependent experiments were also investigated.