物理学报2016，Vol.65Issue(6)：283-290,8.DOI:10.7498/aps.65.067201
Mn掺杂后三元黄铜矿结构半导体CuInTe2的缺陷特征与热电性能∗
Defects and thermo electric p erformance of ternary chalcopyrite CuInTe2-based semiconductors dop ed with Mn
摘要
Abstract
In thermoelectric (TE) semiconductors, there are three physical parameters that govern the TE performance (i.e. Seebeck coefficient (α), electrical conductivity (σ), and thermal conductivity (κ));they are interrelated, hence it is hard to optimize them simultaneously. In order to improve the TE performance, we need to further explore new materials. Ternary chalcopyrite (diamond-like) I-III-VI2 semiconductors (Eg =1.02 eV) are new materials of the TE family, which have potential in conversion between heat and electricity. Since in the ternary chalcopyrite structure, such as Cu(Ag) MTe2, there is an inherent Coulomb attraction between charged defects M2+Cu(Ag) and 2V−Cu(Ag) (a native defect pair, i.e. , metal M-on-Cu or Ag antisites and two Cu or Ag vacancies), hence the electronic and structural properties can easily be tailored if these two defects, along with the creation of other defects, are modified through the introduciton of foreign elements. Besides, the ternary I-III-VI2 compounds often show tetragonal distortion because u ̸= 0.25,η = c/2a ̸= 1 (here u and η are the anion position displacement parameters, and a and c are the lattice parameters), and the cation–anion distances are not equal (dCu—Te=dIn—Te). Any occupation by foreign elements in the cation sites of I-III-VI2 will cause the redistribution of bond charges between I-VI and III-VI, thus leading to a tiny adjustment of the crystal structure and altering the phonon scattering behavior. In this work, we substitute Mn for Cu in the chalcopyrite CuInTe2 and prepare the Cu-poor Cu1−xInMnxTe2 semiconductors. Investigations of Z-ray patterns after Rietveld refinement reveal that Mn prefers In to Cu lattice sites for low Mn content (x < 0.1), thus creating Mn−In as an active acceptor, and improving the carrier concentration (n) and electrical conductivity as Mn content increases. However, Mn can either occupy In or Cu sites simultaneously when x>0.1, and generate both the donor defect Mn+Cu and the acceptor defect Mn−In. In this case, annihilation may occur between these two defects, allowing the reduction in both the defect and carrier concentrations. Because of the annihilation between the two defects, two values (|∆u| = |u−0.25| and |∆η| = |η−1.0|) reduce, this only yields a subtle change in the difference between mean cation-anion distance (RIn—Te−RCu—Te), indicating a small distortion tendency in lattice structure as Mn content increases. Because of this, there is a limited enhancement in lattice thermal conductivity (κL) at high temperatures. As a consequence, we attain an optimal TE performance at a certain Mn content (x=0.05) with the dimensionless figure of merit ZT =0.84@810.0 K, which is about twice as much as that of Mn-free CuInTe2.关键词
热电材料/三元黄铜矿结构半导体/CuInTe2/缺陷特征Key words
thermoelectric performance/ternary chalcopyrite semiconductors/CuInTe2/defects引用本文复制引用
王鸿翔,应鹏展,杨江锋,陈少平,崔教林..Mn掺杂后三元黄铜矿结构半导体CuInTe2的缺陷特征与热电性能∗[J].物理学报,2016,65(6):283-290,8.基金项目
国家自然科学基金(批准号:51171084)、浙江省自然科学基金(批准号：LY14E010003)和宁波市自然科学基金(批准号:2014A610016)资助的课题.* Project supported by the National Natural Science Foundation of China (Grant No.51171084), the Zhejiang Provincial Natural Science Foundation, China (Grant No. LY14E010003), and the Ningbo Natural Science Foundation, China (Grant No.2014A610016) （批准号:51171084）
