核壳结构的Ga_2O_3-SiO_2纳米同轴电缆的制备及其结构表征

Preparation and Characterization of Core-Shell Ga_2O_3-SiO_2 Nanocables

实验利用热蒸发法,以Au覆盖的Si(111)片作为基底,在1 300℃对单质镓加热不同的时间,制备出了一种特殊的纳米同轴电缆结构,并通过SEM(scanning electron microscopy)、XRD(X-ray diffraction)、TEM(transmission electron microscopy)、EDS(energy dispersive spectroscopy)等多种检测手段对样品进行了表征.SEM图像表明该实验制备了大量直径在100~400 nm的纳米结构,而且不同的恒温加热时间会对样品的形貌和结构有显著的影响,通过XRD、TEM、EDS检测确定了这种核壳结构,即外部的SiO_2壳包裹着内部的Ga_2O_3纳米线.最后具体分析了这种核壳结构的可能生长机理:在Ga_2O_3纳米线生长的初期以合金液滴指引的VLS(vapor-liquid-solid)生长机理为主,当Si基底表面覆盖一层纳米材料后,以结构缺陷引导的VS(vapor-solid)生长机理在之后的纳米结构形成过程中起主要作用,而SiO_2外壳是以Ga_2O_3纳米线为模板形成的.

Core-shell structured Ga2O3-SiO2 nanocables were synthesized on gold coated silicon （111） substrate by thermal evaporation at 1 300 ℃ for different time. The samples were characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD） and EDS （energy dispersive spectroscopy）. SEM images showed the nanocables were obtained in large-scale and the diameters were in the range of 100 ~ 400 nm. In addition, the different soaking time had a great influence on the morphology and structure. XRD, TEM and EDS investigations confirmed the core-shell structure, i.e. the core zone was Ga2O3 nanowires and the shell zone was SiO2 layer. Finally, a possible growth mechanism was analyzed in detail. That was, 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, SiO2 grew on the surface of nanowires was taken as templates.