【摘要】 为理解拓扑绝缘体纳米薄膜的电子性质,采用基于密度泛函理论的第一性原理计算方法系统研究拓扑绝缘体Sb2Te3和Bi2Te2Se密排面(0115)薄膜由1层增加到5层的电子结构。通过计算发现对于Sb2Te3密排面(0115)薄膜,随着薄膜层数递增,G点的能隙逐渐减小,当膜厚为5层时,薄膜表现出金属态;Bi2Te2Se密排面(0115)薄膜电子结构也表现出类似的特性。研究结果表明:随着薄膜厚度的增加,Sb2Te3和Bi2Te2Se(0115)薄膜不具有体材料绝缘性,却表现出拓朴绝缘体表面无能隙的金属性。更多还原

【Abstract】 In order to understand electronic properties of topological films,electronic structures of close-packed planes(0115)thin films from one to five layers of Sb2Te3 and Bi2Te2Se were systemic investigated by first-principle method based on the density functional theory.It was found that at G point the gap width tend to decrease as the increasing of Sb2Te3(0115)film layers.The metallic state emerges when the layer of the Sb2Te3(0115)film increases to 5.The similar characters of the electronic structures were found in Bi2Te2Se(0115)film.As the increasing of thickness,the energy gap at G point decreases gradually and the film displays metallic behavior.Our results show that as the increase of film layers both the Sb2Te3 and Bi2Te2Se film lost the insulativity of bulk materials but show gapless metallic surface states of topological insulator.更多还原