在预刻蚀的衬底上通过分子束外延直接生长出拓扑绝缘体薄膜的微器件

Growth of micro-devices of topological insulator thin films by molecular beam epitaxy on substrates pre-patterned with photolithography

在利用光刻将拓扑绝缘体外延薄膜加工成微米尺寸结构的过程中,所用的各种化学物质会导致薄膜质量的下降.在实验中,通过在钛酸锶衬底上预先光刻出Hall bar形状的凸平台并以此为模板进行拓扑绝缘体(Bi x Sb1-x)2Te3薄膜的分子束外延生长,直接获得了薄膜的Hall bar微器件,从而避免了光刻过程对材料质量的影响.原子力显微镜和输运测量结果均显示该微器件保持了(Bi x Sb1-x)2Te3外延薄膜原有的性质.这种新的微器件制备方法有助于在拓扑绝缘体中实现各种新奇的量子效应,并可推广于其他外延生长的低维系统.

In the fabrication of micrometer-sized structures from an epitaxial topological insulator thin film with photolithogra-phy, the film is usually deteriorated by the chemicals used in the process. By molecular beam epitaxy of （BixSb1-x）2Te3 topological insulator onto Hall bar-shaped plateaus pre-lithographed on SrTiO3 substrate, we have directly prepared Hall bar devices of epitaxial topological insulator thin film, avoiding the degradation of film quality in photolithography. Atomic force microscope and transport measurements have demonstrated that the Hall bar devices have the similar properties as that of （BixSb1-x）2Te3 films epitaxied on ordinary SrTiO3 substrates. The new microfabrication method can not only help to realize various novel quantum phenomena predicted in topological insulators but be applied to other epitaxial low-dimensional systems as well.