掺Mn拓扑绝缘体Bi2Se3薄膜的制备及其电磁特性研究

摘要

文章利用分子束外延(molecular beam epitaxy,MBE)法在蓝宝石衬底上制备拓扑绝缘体Bi2Se3和掺杂Mn的拓扑绝缘体Bi2Se3的异质结薄膜.利用反射高能电子衍射仪(reflection high-energy electron diffrac-tion,RHEED)和X射线衍射仪(X-ray diffraction,XRD)对不同条件制备的样品晶相进行分析,获得最优的制备参数,主要包括衬底温度为390℃ 、Bi和Se的流量比为1:10以及Mn流量对应的温度为590℃;利用综合物性测量系统(physical property measurement system,PPMS)测量了样品的温度电阻 、磁电阻和霍尔电阻.测量结果表明,与纯Bi2Se3薄膜相比,Bi2Se3和掺杂Mn的Bi2Se3构成的异质结薄膜的电阻随温度的升高表现出金属性-绝缘性的转变和更强的磁阻特性,而且由于异质层间的近邻效应导致异质薄膜表现出p型导电特性.%In this paper ,the hetero-structural thin films of Bi2Se3 and Mn-doped Bi2Se3 were prepared on sapphire substrate by molecular beam epitaxy (MBE) method .The analyses of the crystalline phase were performed based on the reflection high-energy electron diffraction (RHEED) and X-ray diffrac-tion(XRD) for the thin films prepared at different conditions .The optimal preparation parameters are obtained as follows :the substrate temperature is 390 ℃ ,the flow ratio of Bi and Se is 1 : 10 and the cell temperature for Mn is 590 ℃ .The temperature-dependent resistance ,Hall resistance and magnet-ic resistance of the samples were measured by using the physical property measurement system (PPMS) .The results indicate that compared with the Bi2Se3 thin film ,the resistance of the hetero-structural thin film of Bi2Se3 and Mn-doped Bi2Se3 shows a transition from metallic to insulating char-acters and stronger magnetoresistive properties with the increase of the temperature .Moreover ,this hetero-structural thin film exhibits p-type conducting characteristic due to the proximate interaction .