单晶6H-SiC纳米线的可控掺杂及光学特性

采用有机前驱体制备纳米材料工艺,制备出不同Al掺杂浓度的6H-SiC纳米线(Al/6H-SiC).用HRTEM、EDX、XRD等对纳米线进行了表征,发现随着起始材料中异丙醇铝含量的增加,所制备的纳米线中的Al浓度也在增加,最高可达到1.25%, HRTEM显示晶格间距为0.26 nm和0.25 nm,对应为6H-SiC的(101)和(102)面间距,Si、C原子比为1∶1.拉曼光谱得到这种6H-SiC的声子能量为100 meV,由吸收光谱带边吸收外推计算得到Al/6H-SiC纳米线光学带隙,掺杂浓度越大,吸收边红移越大.

Controlled Synthesis and Doping of Single-Crystalline 6H-SiC Nanowire and Its Optic Properties

Al-doped 6H-SiC nanowires (Al/6H-SiC) were successfully fabricated via catalyst-assisted pyro-lysis of polymeric precursor. The samples were characterized by HRTEM,EDS and XRD. The results showed that the doped concentrations were adjusted from 0.5% up to 1.25% with the Al concentrations in the precursors. The HRTEM pattern illustrated that the lattice fringe spacings pattern demonstrated that Al-doping causes a decrease in the lattice parameters with Al concentration as compared with standard values. The optical properties of single-crystalline 6H-SiC nanowires with different Al doping levels were characterized by Raman and absorption spectra. The Raman spectra reveal that the phonon energy of the single-crystalline SiC nanowire is 100 meV. We estimated the optical absorption band-gap of nanowires from optical band-edge absorption. Al doping results in a red-shift on the optical absorption edge of SiC nanowire, thus it demonstrates a reduction of optical band gap.