Preparation And Characterization Of Gallium Oxide Columnar Structure

As an interdisciplinary high technology,nanotechnology developing in 1990 s mainly studies characteristics and interaction of nanoscale(1-100nm)materials including atoms and molecules.Its aim is to manufacture products with specific functions by advanced nanotechnology equipment,which can benefit to mankind.In the field of nanotechnology,the preparation and characterization of nanomaterials is of great significance to the development of nanotechnology.Nanomaterial is a new research direction in the field of Materials Science in the late twentieth Century.Nanomaterials with one-dimensional size of particle at least in the range of 1 to 100 nm can be divided into zero-dimensional,one-dimensional,two-dimensional and three-dimensional materials.Nano materials have attracted much attention due to their excellent properties,such as high hardness,large specific surface area,high catalytic activity and high conductivity.Two different raw materials,gallium oxide and carbon powder,metallic gallium and gallium oxide powder,are used to synthesize Ga2O3 nanorods and core-shell structured Ga2O3-Si Ox nanocables,respectively.The main researches are as follows:(1)Ga2O3 nanorods were synthesized on gold coated silicon(111)substrate by thermal evaporation at 1300? for 30 min and 60 min and characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-Ray Diffraction(XRD)and Raman spectra.SEM images showed the nanorods were obtained in large-scale according to the VLS growth mechanism.The diameter can reach micro magnitude for 30 min and ranges from 400 nm to 600 nm for 60 min.In addition,the samples are likely to be Ga2O3 by EDS and identified as monoclinic ?-Ga2O3 by XRD and Raman spectra.Finally,a possible growth mechanism was proposed and discussed and Ga2O(intermediate product)played a key role in the formation of nanostructures.(2)Core-shell structured Ga2O3-Si Ox nanocables were synthesized on gold coated silicon(111)substrate by thermal evaporation at 1300? for different time.The samples were characterized by SEM,TEM,XRD,EDS and Raman spectra.SEM images showed the nanocables were obtained in large-scale and the diameter is in the range of 100-400 nm.In addition,the different soaking time had a great influence on the morphology and structure.XRD,TEM,EDS and Raman spectra investigations confirmed the core-shell structure,i.e.the core zone is Ga2O3 nanowires and the shell zone is Si Ox layer.Finally,a possible growth mechanism was analyzed in detail.That is,Ga2O3 nanowires followed VLS mechanism guided by liquid alloys in the initial stage of the growth,but then some Ga2O3 nanowires grew according to the VS mechanism guided by structure defects.In addition,Si Ox grew on the surface of nanowires taken as templates.