溅射沉积Mg2(Sn, Si)薄膜组织结构与导电性能
收稿日期: 2019-04-12
修回日期: 2019-08-12
网络出版日期: 2019-09-02
基金资助
国家自然科学基金项目No(51772193)
Microstructure and Electric Conductance of Mg2(Sn, Si) Thin Films by Sputtering
Received date: 2019-04-12
Revised date: 2019-08-12
Online published: 2019-09-02
Supported by
National Natural Science Foundation of China(51772193)
采用Mg-Sn-Si-Bi合金和高纯Mg双靶，通过转动基材并调节Mg靶溅射时间，在单晶Si(111)衬底上顺序沉积并获得了Mg含量变化的Mg-Sn-Si-Bi薄膜。结果表明，保持合金靶溅射时间不变，薄膜中Mg的含量随Mg靶溅射时间的延长明显增大，同时薄膜中Sn、Si的含量呈减小趋势。薄膜中Mg含量的变化导致其相结构和导电性能发生改变。当Mg含量(原子分数)由71.437%变化到64.497%，薄膜具有单一的立方Mg2(Sn, Si)固溶体相结构；当Mg含量减小到59.813%及以下时，薄膜中Mg2(Sn, Si)固溶体相消失而出现立方Mg2Sn和立方Mg2Si两相；随Mg含量进一步减小到54.006%，薄膜中除Mg2Sn相外还出现了金属Sn相，并且该金属相含量随Mg含量的减少而增大，相应的立方Mg2Sn相含量减少，但Mg2Si相含量几乎没有变化。单一固溶体立方相结构的薄膜具有较大的载流子浓度和迁移率，因此电导率较大。然而，薄膜中金属Sn相的出现导致载流子迁移率显著下降，薄膜导电率也明显降低。
宋贵宏 , 李贵鹏 , 刘倩男 , 杜昊 , 胡方 . 溅射沉积Mg2(Sn, Si)薄膜组织结构与导电性能[J]. 金属学报, 2019 , 55(11) : 1469 -1476 . DOI: 10.11900/0412.1961.2019.00115
The Mg content in Mg2(Sn, Si) films obtained by PVD method often deviates its stoichiometric composition due to the easy evaporation of Mg in low pressure. In order to control the Mg content in Mg2(Sn, Si) lattice and achieve enhancements in thermoelectric efficiency, The Mg-Sn-Si-Bi thin films were deposited on single Si(111) substrate using a Mg-Sn-Si-Bi alloy target and a high pure Mg target by magnetron sputtering alternately. The results show that the Mg content greatly increases, while contents of both Sn and Si decrease in the films with the increasing sputtering time of the Mg target. The thin films possess single cubic Mg2(Sn, Si) solution phase as the Mg content (atomic fraction) is in the range from 71.437% to 64.497%, the Mg2(Sn, Si) solution phase disappear and both of Mg2Sn and Mg2Si phases occur as the Mg content decreases below 59.813% in the films. Furthermore, the Mg2Sn phase decomposes and metal Sn occurs as the Mg content in the films decreases to 54.006%. The metal Sn content increases and the Mg2Sn phase content decreases with the decreasing Mg content in the films, accompanying the near invariable Mg2Sn phase content. XPS spectrum data show that Mg exhibits the tendency to lose electrons. However, the Sn, Si and Bi exhibit the tendency to obtain electrons in deposited films. It is indicated that the Mg-Sn-Si-Bi thin film with single cubic solution phase possesses higher conductivity due to its higher carrier concentration and higher mobility. The mobility greatly decreases due to the occurrence of metal Sn in the films, thus the conductivity of the films greatly decreases.
Key words： Mg2(Sn; Si) film; Mg content; conductivity; mobility; XPS
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