Thermoelectric Properties of Ag-Doped Bi2(Se,Te)3 Compounds: Dual Electronic Nature of Ag-Related Lattice Defects

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• 作者：Meng-Pei Lu ; Chien-Neng Liao ; Jing-Yi Huang ; Hung-Chang Hsu
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：August 3, 2015
• 年：2015
• 卷：54
• 期：15
• 页码：7438-7444
• 全文大小：519K
• ISSN：1520-510X

文摘

Effects of Ag doping and thermal annealing temperature on thermoelectric transport properties of Bi₂(Se,Te)₃ compounds are investigated. On the basis of the comprehensive analysis of carrier concentration, Hall mobility, and lattice parameter, we identified two Ag-related interstitial (Ag_i) and substitutional (Ag_Bi) defects that modulate in different ways the thermoelectric properties of Ag-doped Bi₂(Se,Te)₃ compounds. When Ag content is less than 0.5 wt %, Ag_i plays an important role in stabilizing crystal structure and suppressing the formation of donor-like Te vacancy (V_Te) defects, leading to the decrease in carrier concentration with increasing Ag content. For the heavily doped Bi₂(Se,Te)₃ compounds (>0.5 wt % Ag), the increasing concentration of Ag_Bi is held responsible for the increase of electron concentration because formation of Ag_Bi defects is accompanied by annihilation of hole carriers. The analysis of Seebeck coefficients and temperature-dependent electrical properties suggests that electrons in Ag-doped Bi₂(Se,Te)₃ compounds are subject to a mixed mode of impurity scattering and lattice scattering. A 10% enhancement of thermoelectric figure-of-merit at room temperature was achieved for 1 wt % Ag-doped Bi₂(Se,Te)₃ as compared to pristine Bi₂(Se,Te)₃.