In掺杂对PbTe薄膜结构及电输运特性影响

The Influence of In Doping on the Structure and Electric Transport Characteristics of PbTe Thin Films

摘要: 本文采用分子束外延(MBE)方法在BaF₂(111)衬底上外延生长了Pb_1−xIn_xTe (0.00 ≤ x ≤ 0.20)薄膜。研究结果表明当x ≤ 0.06时，In在PbTe中进行替位式掺杂，形成n型的立方相Pb_1−xIn_xTe结构，薄膜电导率随In掺杂量的增加而增大；当x ≥ 0.10时，In掺杂出现过饱和，过量的In形成In₂Te₃结构相，Pb_1−xIn_xTe薄膜电导率急剧下降。整个掺杂过程中，In均向薄膜表面发生了偏析。综合分析不同In掺杂量下Pb_1−xIn_xTe薄膜的Seebeck系数和电导率测试结果，可以得出In的微量掺杂可实现PbTe薄膜电输运性能的提升，In掺杂量为0.06时薄膜表现出最佳的电输运性能，440K时Pb_1−xIn_xTe (x = 0.06)的功率因子可达9.7 μW∙cm⁻¹∙K⁻²，为本征PbTe最大功率因子的1.2倍。

Abstract: In this paper, Pb_1−xIn_xTe (0.00 ≤ x ≤ 0.20) thin films were epitaxially grown on BaF₂ (111) substrate using molecular beam epitaxy (MBE). The results show that when x ≤ 0.06, In atoms act as substitutional doping in PbTe, forming n type cubic Pb_1−xIn_xTe structure, and their conductivity increase with In doping increasing; When x ≥ 0.10, In atoms are oversaturated in PbTe and In₂Te₃ phase were formed , resulting in the sharply decrease of the film conductivity. In atoms segregate to film surface among the entire doping process. Comprehensive analysis of the Seebeck coefficient and conductivity test results of different In doping Pb_1-xIn_xTe films, we can obtain that electrical transport properties of PbTe can be improved by trace In doping, and Pb_1-xIn_xTe (x = 0.06) thin film is the optimum, its power factor at 440K can be up to 9.7 μW∙cm⁻¹∙K⁻² at 400 K, which is 1.2 times greater than that of PbTe.