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The NiAs-type MnTe compound is one of important and environmental friendly p-type thermoelectric materials for generating intermediate temperature powern. The low hole concentration in the pristine MnTe greatly restricts its thermoelectric performance. However, the systematic experimental studies of thermoelectric materials are still lacking so far. In this work, MnTe thin films are grown by molecular beam epitaxy (MBE) technique, and their intrinsic point defect structures are characterized by scanning tunneling microscope (STM). Through the regulation of the intrinsic point defects, the electrical transport performances of MnTe films are remarkably improved. The results show that Mn vacancies (VMn) and Te vacancies (VTe) are the dominant intrinsic point defects in MnTe film. With the increase of the substrate temperature (Tsub) and the decrease of the Mn:Te flux ratio, the hole concentration in MnTe film increases greatly, reaching a maximum value of 21.5 × 1019 cm–3, which is one order of magnitude higher than that of the intrinsic MnTe bulk. This is attributed to the significantly increased concentration of p-type VMn in MnTe film, and thus leads the conductivity (σ) and power factor (PF) to increase remarkably. Finally, the MnTe film grown at Tsub = 280 ℃ and Mn∶Te = 1∶12 obtains the maximum PF of 1.3 μW·cm–1·K–2 at 483 K in all grown films. This study clarifies the characteristics of intrinsic point defects and their relationship with the electrical transport properties of MnTe based compounds, which provides an importantguidance for further optimizing their thermoelectric performances.
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Keywords:
- MnTe films /
- molecular beam epitaxy /
- intrinsic point defect /
- electrical transport properties
[1] Uher, Ctirad 2016 Materials Aspect of Thermoelectricity (New York: Taylor & Francis Group) pp39–94
[2] 陈立东, 刘睿恒, 史迅 2018 热电材料与器件 (北京: 科学出版社) 第16—39页
Chen L D, Liu H R, Si X 2018 Thermoelectric Materials and Devices (Beijing: Science Press) pp16–39 (in Chinese)
[3] Xu Y, Li W, Wang C, Li J, Chen Z, Lin S, Chen Y, Pei Y 2017 J. Mater. Chem. A 5 19143Google Scholar
[4] Zhao L D, Kanatzidis M G 2016 J. Materiomics 2 101Google Scholar
[5] Du B S, Jian J K, Liu H T, Liu J, Qiu L 2018 Chin. Phys. B 27 048102Google Scholar
[6] 王步升, 刘永 2016 65 066101Google Scholar
Wang B S, Yong L 2016 Acta Phys. Sin. 65 066101Google Scholar
[7] Kriegner D, Reichlova H, Grenzer J, Schmidt W, Ressouche E, Godinho J, Wagner T, Martin S, Shick A, Volobuev V 2017 Phys. Rev. B 96 214418Google Scholar
[8] Ren Y, Jiang Q, Zhang D, Zhou Z, Li X, Xin J, He X 2017 J. Mater. Chem. C 5 5076Google Scholar
[9] 娄许诺, 邓后权, 李爽, 张青堂, 熊文杰, 唐国栋 2021 无 机 材 料 学 报 36(3)
Lou X N, Deng H Q, Li S, Zhang Q T, Xiong W J, Tang G D 2021 J. Inorg. Mater. 36 (in Chinese)
[10] Deng H, Lou X, Lu W, Zhang J, Li D, Li S, Zhang Q, Zhang X, Chen X, Zhang D 2020 Nano Energy 81 105649
[11] Sreeram P, Ganesan V, Thomas S, Anantharaman M 2020 J. Alloys Compd. 836 155374Google Scholar
[12] Basit A, Yang J, Jiang Q, Zhou Z, Xin J, Li X, Li S 2019 J. Alloys Compd. 777 968Google Scholar
[13] Ren Y, Jiang Q, Yang J, Luo Y, Zhang D, Cheng Y, Zhou Z 2016 J. Materiomics 2 172Google Scholar
[14] Xin J, Yang J, Jiang Q, Li S, Basit A, Hu H, Long Q, Li S, Li X 2019 Nano Energy 57 703Google Scholar
[15] Dong J, Sun F H, Tang H, Hayashi K, Li H, Shang P P, Miyazaki Y, Li J F 2019 ACS Appl. Mater. Interfaces 11 28221Google Scholar
[16] Dong J, Pei J, Hayashi K, Saito W, Li H, Cai B, Miyazaki Y, Li J F 2021 J. Materiomics 7 577Google Scholar
[17] Zhang M, Liu W, Zhang C, Xie S, Li Z, Hua F, Luo J, Wang Z, Wang W, Yan F, Cao Y, Liu Y, Wang Z, Uher C, Tang X 2021 ACS Nano 15 5706Google Scholar
[18] Watanabe R, Yoshimi R, Shirai M, Tanigaki T, Kawamura M, Tsukazaki A, Takahashi K, Arita R, Kawasaki M, Tokura Y 2018 Appl. Phys. Lett. 113 181602Google Scholar
[19] Su S H, Chang J T, Chuang P Y, Tsai M C, Peng Y W, Lee M K, Cheng C M, Huang J C 2021 Nanomaterials 11 3322Google Scholar
[20] He Q L, Yin G, Grutter A J, Pan L, Che X, Yu G, Gilbert D A, Disseler S M, Liu Y, Shafer P, Zhang B, Wu Y, Kirby B J, Arenholz E, Lake R K, Han X, Wang K L 2018 Nat. Commun. 9 2767Google Scholar
[21] Aliev Z S, Amiraslanov I R, Nasonova D I, Shevelkov A V, Abdullayev N A, Jahangirli Z A, Orujlu E N, Otrokov M M, Mamedov N T, Babanly M B, Chulkov E V 2019 J. Alloys Compd. 789 443Google Scholar
[22] Islam M F, Canali C M, Pertsova A, Balatsky A, Mahatha S K, Carbone C, Barla A, Kokh K A, Tereshchenko O E, Jiménez E, Brookes N B, Gargiani P, Valvidares M, Schatz S, Peixoto T R F, Bentmann H, Reinert F, Jung J, Bathon T, Fauth K, Bode M, Sessi P 2018 Phys. Rev. B 97 155429Google Scholar
[23] Li Y, Wang S, Sun B, Chang H, Zhao W, Zhang X, Liu H 2013 ECS Transactions 50 303
[24] Nesbitt H, Banerjee D 1998 Am. Mineral. 83 305Google Scholar
[25] 何俊, 李梦, 郭立平, 刘传胜, 付德君 2008 核技术 31 438Google Scholar
He J, Li M, Guo L P, Liu C S, Fu D J 2008 Nucl. Tech. 31 438Google Scholar
[26] Biesinger M C, Payne B P, Grosvenor A P, Lau L W M, Gerson A R, Smart R S C 2011 Appl. Surf. Sci. 257 2717Google Scholar
[27] Iwanowski R J, Heinonen M H, Witkowska B 2010 J. Alloys Compd. 491 13Google Scholar
[28] 吴海飞, 张寒洁, 廖清, 陆豪, 斯剑霄, 李海洋, 鲍世宁, 吴惠祯, 何丕模 2009 58 1310Google Scholar
Wu H F, Zhang H J, Liao Q, Lu H, Si J X, Li H Y, Bao S N, Wu H Z, He P M 2009 Acta Phys. Sin. 58 1310Google Scholar
[29] She X Y, Su X L, Xie H Y, Fu J F, Yan Y, Liu W, Poudeu Poudeu P F, Tang X F 2018 ACS Appl. Mater. Interfaces 10 25519Google Scholar
[30] Gong Y, Guo J, Li J, Zhu K, Liao M, Liu X, Zhang Q, Gu L, Tang L, Feng X, Zhang D, Li W, Song C, Wang L, Yu P, Chen X, Wang Y, Yao H, Duan W, Xu Y, Zhang S C, Ma X, Xue Q K, He K 2019 Chin. Phys. Lett. 36 076801Google Scholar
[31] Netsou A M, Muzychenko D A, Dausy H, Chen T, Song F, Schouteden K, Van Bael M J, Van Haesendonck C 2020 ACS Nano 14 13172Google Scholar
[32] Zhang M, Liu W, Zhang C, Qiu J, Xie S, Hua F, Cao Y, Li Z, Xie H, Uher C 2020 Appl. Phys. Lett. 117 153902Google Scholar
[33] 逯旭, 侯绩翀, 张强, 樊建锋, 陈少平, 王晓敏 2021 无机材料学报 36
Lu X, Hou J C, Zhang Q, Fan J F, Chen S P, Wang X M 2021 J. Inorg. Mater. 36 (in Chinese)
[34] Bahk J H, Shakouri A 2016 Phys. Rev. B 93 165209Google Scholar
[35] Zhang Q, Hou J, Fan J, Chen S, Fan W, Zhang H, Wang W, Wu Y, Xu B 2020 Phys. Chem. Chem. Phys. 22 7012Google Scholar
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图 1 (a)六方相MnTe的晶体结构; (b)基板温度为280 ℃ , Sb2Te3∶Te = 1∶1条件下生长Sb2Te3缓冲层的RHEED图谱; (c)基板温度为280 ℃ , Mn∶Te = 1∶9条件下生长的MnTe薄膜的RHEED图谱; (d), (e)不同基板温度和不同Mn∶Te束流比工艺下生长的MnTe薄膜的XRD图谱
Figure 1. (a) Crystal structure of hexagonal MnTe; RHEED patterns of (b) Sb2Te3 buffer layer grown at Tsub = 280 ℃ and Sb2Te3∶Te = 1∶1 and (c) MnTe film grown at Tsub = 280 ℃ and Mn∶Te = 1∶9; XRD patterns of MnTe thin films grown at (d) different Tsub and (e) under different Mn∶Te ratios.
图 3 不同基板温度下生长的MnTe薄膜的原子尺度分辨STM形貌图 (a)Tsub = 260 ℃; (b)Tsub = 280 ℃; (c)—(f)暗凹陷点缺陷与暗三角形缺陷在正负偏压下的STM形貌图; (g) MnTe晶体结构沿c轴的截面图, 其中黄红色粗线条用于示意第二层点缺陷的局域电子态在表面的投影
Figure 3. Atomic resolution STM images of MnTe films grown at different Tsub: (a) Tsub = 260 ℃; (b) Tsub = 280 ℃. (c)–(f) STM images of the dark depressions point defect and dark triangle defect under positive and negative STM tip bias. (g) A cross-sectional sketch of the MnTe crystal structure along the c axis, in which the thick yellow-red line is used to indicate the projection of the local electronic state on the surface from the second layer point defects.
图 4 (a)固定Mn∶Te = 1∶6, 在不同Tsub条件下生长的MnTe薄膜的室温空穴浓度与载流子迁移率; 不同Tsub条件下生长的MnTe薄膜的(b)电导率、(c)Seebeck系数和(d)功率因子随温度的变化关系
Figure 4. Room temperature (a) hole concentration and (p) carrier mobility (μ) of MnTe thin films grown at different Tsub. The temperature dependence of (b) electrical conductivity , (c) Seebeck coefficient and (d) power factor for these MnTe films grown at different Tsub.
图 5 (a)固定Tsub = 280 ℃, 不同Mn∶Te束流比条件下生长的MnTe薄膜的室温空穴浓度与载流子迁移率; 不同Tsub条件下生长的MnTe薄膜的(b)电导率、(c)Seebeck系数和(d)功率因子随温度的变化关系
Figure 5. Room temperature (a) hole concentration and (p) carrier mobility (μ) of MnTe thin films grown at different Tsub. The temperature dependence of (b) electrical conductivity, (c) Seebeck coefficient and (d) power factor for these MnTe films grown at different Tsub.
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[1] Uher, Ctirad 2016 Materials Aspect of Thermoelectricity (New York: Taylor & Francis Group) pp39–94
[2] 陈立东, 刘睿恒, 史迅 2018 热电材料与器件 (北京: 科学出版社) 第16—39页
Chen L D, Liu H R, Si X 2018 Thermoelectric Materials and Devices (Beijing: Science Press) pp16–39 (in Chinese)
[3] Xu Y, Li W, Wang C, Li J, Chen Z, Lin S, Chen Y, Pei Y 2017 J. Mater. Chem. A 5 19143Google Scholar
[4] Zhao L D, Kanatzidis M G 2016 J. Materiomics 2 101Google Scholar
[5] Du B S, Jian J K, Liu H T, Liu J, Qiu L 2018 Chin. Phys. B 27 048102Google Scholar
[6] 王步升, 刘永 2016 65 066101Google Scholar
Wang B S, Yong L 2016 Acta Phys. Sin. 65 066101Google Scholar
[7] Kriegner D, Reichlova H, Grenzer J, Schmidt W, Ressouche E, Godinho J, Wagner T, Martin S, Shick A, Volobuev V 2017 Phys. Rev. B 96 214418Google Scholar
[8] Ren Y, Jiang Q, Zhang D, Zhou Z, Li X, Xin J, He X 2017 J. Mater. Chem. C 5 5076Google Scholar
[9] 娄许诺, 邓后权, 李爽, 张青堂, 熊文杰, 唐国栋 2021 无 机 材 料 学 报 36(3)
Lou X N, Deng H Q, Li S, Zhang Q T, Xiong W J, Tang G D 2021 J. Inorg. Mater. 36 (in Chinese)
[10] Deng H, Lou X, Lu W, Zhang J, Li D, Li S, Zhang Q, Zhang X, Chen X, Zhang D 2020 Nano Energy 81 105649
[11] Sreeram P, Ganesan V, Thomas S, Anantharaman M 2020 J. Alloys Compd. 836 155374Google Scholar
[12] Basit A, Yang J, Jiang Q, Zhou Z, Xin J, Li X, Li S 2019 J. Alloys Compd. 777 968Google Scholar
[13] Ren Y, Jiang Q, Yang J, Luo Y, Zhang D, Cheng Y, Zhou Z 2016 J. Materiomics 2 172Google Scholar
[14] Xin J, Yang J, Jiang Q, Li S, Basit A, Hu H, Long Q, Li S, Li X 2019 Nano Energy 57 703Google Scholar
[15] Dong J, Sun F H, Tang H, Hayashi K, Li H, Shang P P, Miyazaki Y, Li J F 2019 ACS Appl. Mater. Interfaces 11 28221Google Scholar
[16] Dong J, Pei J, Hayashi K, Saito W, Li H, Cai B, Miyazaki Y, Li J F 2021 J. Materiomics 7 577Google Scholar
[17] Zhang M, Liu W, Zhang C, Xie S, Li Z, Hua F, Luo J, Wang Z, Wang W, Yan F, Cao Y, Liu Y, Wang Z, Uher C, Tang X 2021 ACS Nano 15 5706Google Scholar
[18] Watanabe R, Yoshimi R, Shirai M, Tanigaki T, Kawamura M, Tsukazaki A, Takahashi K, Arita R, Kawasaki M, Tokura Y 2018 Appl. Phys. Lett. 113 181602Google Scholar
[19] Su S H, Chang J T, Chuang P Y, Tsai M C, Peng Y W, Lee M K, Cheng C M, Huang J C 2021 Nanomaterials 11 3322Google Scholar
[20] He Q L, Yin G, Grutter A J, Pan L, Che X, Yu G, Gilbert D A, Disseler S M, Liu Y, Shafer P, Zhang B, Wu Y, Kirby B J, Arenholz E, Lake R K, Han X, Wang K L 2018 Nat. Commun. 9 2767Google Scholar
[21] Aliev Z S, Amiraslanov I R, Nasonova D I, Shevelkov A V, Abdullayev N A, Jahangirli Z A, Orujlu E N, Otrokov M M, Mamedov N T, Babanly M B, Chulkov E V 2019 J. Alloys Compd. 789 443Google Scholar
[22] Islam M F, Canali C M, Pertsova A, Balatsky A, Mahatha S K, Carbone C, Barla A, Kokh K A, Tereshchenko O E, Jiménez E, Brookes N B, Gargiani P, Valvidares M, Schatz S, Peixoto T R F, Bentmann H, Reinert F, Jung J, Bathon T, Fauth K, Bode M, Sessi P 2018 Phys. Rev. B 97 155429Google Scholar
[23] Li Y, Wang S, Sun B, Chang H, Zhao W, Zhang X, Liu H 2013 ECS Transactions 50 303
[24] Nesbitt H, Banerjee D 1998 Am. Mineral. 83 305Google Scholar
[25] 何俊, 李梦, 郭立平, 刘传胜, 付德君 2008 核技术 31 438Google Scholar
He J, Li M, Guo L P, Liu C S, Fu D J 2008 Nucl. Tech. 31 438Google Scholar
[26] Biesinger M C, Payne B P, Grosvenor A P, Lau L W M, Gerson A R, Smart R S C 2011 Appl. Surf. Sci. 257 2717Google Scholar
[27] Iwanowski R J, Heinonen M H, Witkowska B 2010 J. Alloys Compd. 491 13Google Scholar
[28] 吴海飞, 张寒洁, 廖清, 陆豪, 斯剑霄, 李海洋, 鲍世宁, 吴惠祯, 何丕模 2009 58 1310Google Scholar
Wu H F, Zhang H J, Liao Q, Lu H, Si J X, Li H Y, Bao S N, Wu H Z, He P M 2009 Acta Phys. Sin. 58 1310Google Scholar
[29] She X Y, Su X L, Xie H Y, Fu J F, Yan Y, Liu W, Poudeu Poudeu P F, Tang X F 2018 ACS Appl. Mater. Interfaces 10 25519Google Scholar
[30] Gong Y, Guo J, Li J, Zhu K, Liao M, Liu X, Zhang Q, Gu L, Tang L, Feng X, Zhang D, Li W, Song C, Wang L, Yu P, Chen X, Wang Y, Yao H, Duan W, Xu Y, Zhang S C, Ma X, Xue Q K, He K 2019 Chin. Phys. Lett. 36 076801Google Scholar
[31] Netsou A M, Muzychenko D A, Dausy H, Chen T, Song F, Schouteden K, Van Bael M J, Van Haesendonck C 2020 ACS Nano 14 13172Google Scholar
[32] Zhang M, Liu W, Zhang C, Qiu J, Xie S, Hua F, Cao Y, Li Z, Xie H, Uher C 2020 Appl. Phys. Lett. 117 153902Google Scholar
[33] 逯旭, 侯绩翀, 张强, 樊建锋, 陈少平, 王晓敏 2021 无机材料学报 36
Lu X, Hou J C, Zhang Q, Fan J F, Chen S P, Wang X M 2021 J. Inorg. Mater. 36 (in Chinese)
[34] Bahk J H, Shakouri A 2016 Phys. Rev. B 93 165209Google Scholar
[35] Zhang Q, Hou J, Fan J, Chen S, Fan W, Zhang H, Wang W, Wu Y, Xu B 2020 Phys. Chem. Chem. Phys. 22 7012Google Scholar
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