SiC/SiO_2核壳结构纳米线制备及光学性质研究

Synthesis and photoluminescence propoerties of the SiC/SiO_2 coreshell nanowires

采用简单的气固反应,在Si衬底上成功制备了SiC一维纳米材料。用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线电子能谱(EDX)、X射线衍射谱(XRD)和光致发光谱(PL)等手段研究了材料的表面形貌、结构组成和光学性质。研究结果表明,制备的纳米材料为SiC/SiO2核壳结构纳米线,在室温时发射中心波长分别为380nm和505nm的紫外峰和绿光带。经分析认为,波长380nm的紫外峰来源于SiO2中的O空位缺陷;而中心波长505nm的绿光带则来源于受量子尺寸效应影响并包覆了SiO2外壳的SiC内核。

Due to the indirect band gap structure,the light emission efficiency of SiC materials is usually very low,which limits the applications of SiC in optoelectronic devices.A lot of methods have been employed to improve the light emission efficiency of SiC materials,of which synthesizing SiC nano-structure materials would be an effective way.In our work,SiC/SiO2core-shell nanowires were synthesized on Si（100）substrate by the reaction of methane with silicon dioxide using iron as catalyst.The structural properties of the nanowires are characterized by scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and X-ray diffraction（XRD）.It can be seen that the nanowires have a diameter about 50nm and length about 10μm,and the nanowires consist of a 30nm single-crystalβ-SiC core and a 10nm amorphous SiO2shell.The light-emitting properties of nanowires are studied by photoluminescence spectroscopy.A sharp ultraviolet peak at 380nm and an intensive broad green band with defined maximum peak at 505nm are observed in PL spectra of as-grown nanowires.According to analysis,the ultraviolet peak originates from the oxygen-vacancy defects in the SiO2shell and the broad green band comes from the SiC cores caused by quantum confinement effect.