Bi_(2)Se_(3)纳米线的生长及其圆偏振光电流的研究

Growth and circular photogalvanic effect investigation of Bi_(2)Se_(3) nanowires

采用化学气相沉积法制备拓扑绝缘体Bi_(2)Se_(3)纳米线.系统分析生长温度和气体流量对Bi_(2)Se_(3)纳米线的形貌、晶体质量的影响,并研究Bi_(2)Se_(3)纳米线的圆偏振光致电流.研究结果表明,Bi_(2)Se_(3)纳米线的最佳生长温度为530℃,气体流量为30 mL·min^(-1).通过扫描电子显微镜、透射电子显微镜、拉曼等表征手段,表明所生长的Bi_(2)Se_(3)纳米线具有较高的质量.Bi_(2)Se_(3)纳米线的光电流随着四分之一波片的变化表明,Bi_(2)Se_(3)纳米线具有较强的自旋轨道耦合效应.圆偏振光致电流随入射角的增大而减小,这是因为Bi_(2)Se_(3)的对称性结构为C3V.相比Bi_(2)Se_(3)薄膜或者Bi_(2)Se_(3)纳米片,Bi_(2)Se_(3)纳米线具有更大的CPGE电流,这可能是因为纳米线具有更大的比表面积,可以避免表面态信号淹没在体态信号中.

In this paper,Bi_(2)Se_(3)nanowires were grown by chemical vapor deposition.The effects of growth temperature and gas flow rate on the morphology and crystal quality of Bi_(2)Se_(3)nanowires were systematically studied,and the Bi_(2)Se_(3)nanowires were fabricated into a single nanowire device to study the circular photogalvanic effect of Bi_(2)Se_(3)nanowire.The results show that the optimum growth conditions of Bi_(2)Se_(3)nanowires are temperature 530℃and gas flow 30 mL·min^(-1).Scanning electron microscope,transmission electron microscope,Raman spectra and other characterization methods show that the grown Bi_(2)Se_(3)nanowires have high quality.The dependence of the photocurrent induced by the circular photogalvanic effect of the Bi_(2)Se_(3)nanowire on incident angle indicates that the symmetric structure of Bi_(2)Se_(3)is C3V.Compared with Bi_(2)Se_(3)thin films or Bi_(2)Se_(3)nanoplates,Bi_(2)Se_(3)nanowires have larger CPGE due to significantly enhanced surface-to-volume ratio,which can avoid the contributions from surface states are masked by the bulk carriers.