本論文研究摻雜不同濃度釤離子氧化鋅薄膜之光譜性質及單層 過渡金屬二硫屬化合物MX
2
( M = Mo, W；X = S, Se)薄膜之變溫光譜 特性。我們使用拉曼散射光譜、穿透光譜及橢圓偏振光譜研究樣品的 晶格與電子結構。根據實驗結果，我們歸納以下幾點結論:摻雜不同濃度釤離子氧化鋅薄膜:
第一，由拉曼散射光譜得知氧化鋅之 E
2
(low) 和 E2
(high)振動模 隨摻雜濃度上升，強度減弱，半高增大。由於摻雜改變樣品應力，造 成E2
(high)紅移。E2
(low)的藍移現象原因不明，需要更進一步的理論計算。當摻雜濃度大於3%，此兩個特徵峰訊號簡無法辨識。
第二，根據穿透光譜得知摻雜釤離子導致整體穿透率隨摻雜濃度 上升。穿透光譜及橢圓偏振光譜皆顯示氧化鋅之自由激子吸收峰隨摻
雜濃度增加而逐漸消失；能隙隨摻雜濃度增加而上升，依據 X 光繞射
光譜之結果，我們推測低濃度摻雜樣品(≤5%)能隙增寬的現象可由柏 斯坦-莫斯位移理論(Burstein-Moss effect)解釋；高濃度摻雜樣品(≥8%) 趨向Zn
1-x
Smx
O 合金之能帶結構。第三，我們成功擬合氧化鋅橢圓偏振光譜數據，取得摻雜不同濃 度釤離子氧化鋅薄膜之光學常數。
126
單層過渡金屬二硫屬化合物薄膜:
第一
，
由拉曼散射光譜可應證所有樣品皆為單層薄膜。第二，單層MoS
2
、MoSe2
、WS2
及WSe2
薄膜之自旋耦合分裂能 量分別為 0.16、0.25、0.39 及 0.44 eV，且此數值不隨溫度改變而變 化。第三，比對第一原理計算結果[74]，我們推測在 4.5 K，MoS
2
之 2.94 eV 及 3.20 eV 之吸收峰分別來自布里淵區 Λ 及 M 點的躍遷；MoSe
2
之2.65 eV 及 3.10 eV 吸收峰分別來自布里淵區 Λ 及 M 點的躍 遷；WS2
之 3.12 eV 和 3.41 eV 吸收峰為布里淵區 Λ 點的躍遷，4.17 eV 吸收峰為布里淵區 M 點的躍遷；WSe2
之2.56 eV 及 3.12 eV 吸收 峰為布里淵區Λ 點的躍遷，4.19 eV 吸收峰為布里淵區 M 點的躍遷。第四，我們使用玻色愛因斯坦模型擬合單層MoS
2
、MoSe2
、WS2
及WSe
2
薄膜光學能隙隨溫度變化之數據，單層MoS2
、MoSe2
、WS2
及WSe
2
薄膜在 0 K 之光學能隙為 1.99、1.65、2.15 及 1.74 eV；電子 聲子交互作用強度分別為 36、26、37 及 29 meV；聲子平均溫度為 225.3、171.2、200.7 及 165.8 K，與使用 Varshni 公式擬合所得之 Debye 溫度235.6、133.2、178.7、124.2 K 相近。第五，我們成功擬合隨溫度變化之單層 MoS
2
、MoSe2
、WS2
及 WSe2
薄膜之橢圓偏振光譜數據，取得變溫光學常數。127
未來我們將量測單層MoS
2
、MoSe2
、WS2
及WSe2
薄膜外加強磁 場及圓偏振吸收光譜研究。依據 Y. Tatsumi 等人[74]之計算結果，Λ點與K 點相似，對於左旋及右旋偏振光具有選擇率，且也因強烈自旋
耦合造成導帶及價帶分裂，因此進行外加強磁場及圓偏振吸收光譜研 究能夠更進一步了解此能量區域之電子能帶結構。
128
參考文獻
[1] Ü. Özgür, Y. Alivov, C. Liu, A. Teke, M. Reshchikov, S. Dogan, V.
Avrutin, S. Cho, and H. Morkoç, “A comprehensive review of ZnO materials and devices”, J. Appl. Phys. 98, 041301 (2005).
[2] K. Keis, E. Magnusson, H. Lindström, S. Lindquist, and A. Hagfeldt,
“A 5% efficient photoeletrochemical solar cell based on nanostructured ZnO electroes”, Solar Energy Materials & Solar Cells
73, 51 (2002).
[3] S. Ko, D. Lee, H. Kang, K. Nam, J. Yeo, S. Hong, C. Grigoropoulos, and H. Sung, “ Nanoforest of hydrothermally grown hierarchical ZnO nanowires for a high efficiency dye-sensitized solar cell”, Nano Lett.
11, 666 (2011).
Koinuma, and M. Kawasaki, “Repeated temperature modulation epitaxy for p-type doping and light-emitting diode based on ZnO”, Nature Materials 4, 42 (2005).
[6] H. Liang, S. Yu, and H. Yang, “ZnO random laser diode arrays for stable single-mode operation at high power”, Appl. Phys. Lett. 97, 241107 (2010).
[7] J. Guo, J. Zhang, M. Zhu, D. Ju, H. Xu, and B. Cao, “High-performance gas sensor based on ZnO nanowires functionalized by Au nanoparticales”, Sensor and Actuators B: Chemical 199, 339 (2014).
[8] J. Yoo, T. Ahmed, W. Tang, Y. Kim, Y. Hong, C. Lee, and G. Yi,
“Single crystalline ZnO radial homojunction light-emitting diodes fabricated by metalorganic chemical vapour deposition”, Nanotechnology 28, 394001 (2017).
[9] K. Kittilstved, N. Norberg, and D. Gamelin, “Chemical manipulation of High-T
C
ferromagnetism in ZnO diluted magnetic semiconductors”, Phys. Rev. Lett. 94, 147209 (2005).[10] J. Yi, C. Lin, G. Xing, H. Fan, L. Van, S. Huang, K. Yang, X. Huang, X. Qin, B. Wang, T. Wu, L. Wang, H. Zhang, X. Gao, T. Liu, A. Wee, Y. Feng, and J. Ding, “Ferromagnetism in dilute magnetic
129
semiconductors through defect engineering: Li-doped ZnO”, Phys.
Rev. Lett. 104, 137201 (2010).
[11] K. Novoselov, A. Geim, S. Morozov, D. Jiang, Y. Zhang, S. Dubonos, I. Grigorieva, and A. Firsov, “Electric field effect in atomically thin carbon films”, Science 306, 666 (2004).
[12] Q. Wang, K. Kalantar-Zadeh, A. Kis, J. Coleman, and M. Strano,
“Electronics and optoelectronics of two-dimensional transition metal duchalcogenides”, Nature Nanotechnology 7, 699 (2012).
[13] Y. Li, A. Chernikov, X. Zhang, A. Rigosi, H. Hill, A. van der Zande, D. Chenet, E. Shih, J. Hone, and T. Heinz, “Measurement of the optical dielectric function of monolayer transition-metal dichalcogenides: MoS
2
, MoSe2
, WS2
, and WSe2
”, Phys. Rev. B 90, 205422 (2014).[14] K. Matsuda, “Optical properties of atomically thin layered transition metal dichalchogenide”, J. Phys. Soc. Jpn. 84, 121009 (2015).
[15] Y. Morozov and M. Kuno, “Optical constants and dynamic conductivities of single layer MoS
2
, MoSe2
, and WSe2
” Appl. Phys.Lett. 107, 083103 (2015).
[16] H. Park, T. Kim, H. Kim, C. Yoo, N. Barange, V. Le, H. Kim, V.
Senthilkumar, C. Le, Y. Kim, M. Seong, and Y. Kim, “Temperature dependence of the critical points of monolayer MoS
2
by ellipsometry”, Applied Spectroscopy Review 51, 621 (2016).[17] B. Jin, S. Im, and S. Lee, “Violet and UV luminescence emitted from ZnO thin films grown on sapphire by pulsed laser deposition”, Thin Solid Films 366, 107 (2000).
[18] G. Martaza Rai, M. Iqbal, Y. Xu, and I. Will, Z. Huang, “Study of Sm-doped ZnO samples sintered in a nitrogen atmosphere and deposited on n-Si(100) by evaporation technique”, Journal of Magnetism and Magnetic Materials 323, 3239 (2011).
[19] T. Prasada Rao, S. Gokul Raj, and M. C. Santhosh Kumar, “Optical properties of Samarium doped ZnO thin films”, ICDCS 2, 1 (2014).
[20] H. He, J. Fei, and J. Lu, “Sm-doping effect on optical and electrical properties of ZnO films”, J. Nanostruct. Chem. 5, 169 (2015).
[21] A. Kuc, N. Zibouche, and T. Heine, “Influence of quantum confinement on the electronic structure of the transition metal sulfide TS
2
”, Phys. Rev. B 83, 245213 (2011).[22] W. Huang, X. Luo, C. Gan, S. Quek, and G. Liang, “Theoretical study of thermoelectric properties of few-layer MoS
2
and WSe2
”, Phys.130
Chem. Chem. Phys. 16, 10866 (2014).
[23] S. Tongay, J. Zhou, C. Ataca, K. Lo, T. Matthews, J. Li, J. Grossman, and J. Wu, “Thermally driven crossover from indirect toward direct bandgap in 2D semiconductors: MoSe
2
versus MoS2
”, Nano Lett. 12, 5576 (2012).[24] K. Mak, C. Lee, J. Hone, J. Shan, and T. Heinz, “Atomically Thin MoS
2
: A new direct-gap semiconductor” Phys. Rev. Lett. 105, 136805 (2010).[25] W. Zhao, Z. Ghorannevis, L. Chu, M. Toh, C. Kloc, P. Tan, and G. Eda,
“Evolution of electronic structure in atomically thin sheets of WS
2
and WSe
2
”, ACS Nano 7, 791 (2013).“Giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor”, Nature Materials 13, 1091 (2014).
[28] H. Liu, L. Jiao, L. Xie, F. Yang, J. Chen, W. Ho, C. Gao, J. Jia, X.
Cui, and M. Xie, “Molecular-beam epitaxy of monolayer and bilayer WSe
2
: a scanning tunneling microscopy/spectroscopy study and deduction of exciton binding energy”, 2D Mater. 2, 034004 (2015).[29] A. Arora, M. Koperski, K. Nogajewski, J. Marcus, C. Faugeras, and M. Potemski, “Excitonic resonances in thin films of WSe
2
: from monolayer to bulk material”, Nanoscale 7, 10421 (2015).[30] A. Arora, K. Nogajewski, M. Molas, M. Koperski, and M. Potemski,
“Exciton band structure in layered MoSe
2
: from a monolayer to the bulk limit”, Nanoscale 7, 20769 (2015).[31] S. Eichfeld, C. Eichfeld, Y. Lin, L. Hossain, and J. Robinson, “Rapid, non-destructive evaluation of ultrathin WSe
2
using spectroscopic ellipsometry”, APL Materials 2, 092508 (2014).[32] W. Zhao, R. Ribeiro, M. Toh, A. Carvallo, C. Kloc, A. Castro Neto, and G. Eda, “Origin of indirect optical transitions in few-layer MoS
2
, WS2
, and WSe2
”, Nano Lett. 13, 5627 (2013).[33] C. Yim, M. O’Brien, N. McEcoy, S. Winters, I. Mirza, J. Lunney, and G. Duesberg, “Investigation of the optical properties of MoS
2
thin131
films using spectroscopic ellipsometry”, Appl. Phys. Lett. 104, 103114 (2014).
[34] 林宜霖，以拉曼散射光譜研究 Sr
2
Y(Ru1-x
Cux
)O6
與 Fe(Se, Te)atomic layers with chemical vapor deposition”, Adv. Mater. 24, 2320 (2012).
[37] Y. Chang, W. Zhang, Y. Zhu, Y. Han, J. Pu, J. Chang, W. Hsu, J. Huang, C. Hsu, M. Chiu, T. Takenobu, H. Li, C. Wu, W. Chang, A. Wee, and L. Li, “Monolayer MoSe
2
grown by chemical vapor deposition for fast photodetection”, ACS Nano 8, 8582 (2014).[38] Y. Lee, L. Yu, H. Wang, W. Fang, X. Ling, Y. Shi, C. Lin, J. Huang, M. Chang, C. Chang, M. Dresselhaus, T. Palacios, L. Li, and J. Kong,
“Synthesis and transfer of single-layer transition metal disulfides on diverse surfaces”, Nano Lett. 13, 1852 (2013).
[39] J. Huang, J. Pu, C. Hsu, M. Chiu, Z. Juang, Y. Chang, W. Chang, Y.
Iwasa, T. Takenobu, and L. Li, “Large-area synthesis of highly crystalline WSe
2
monolayers and device applications”, ACS Nano 8, 923 (2014).[40] C. A. Arguello, D. L. Rousseau, and S. P. S. Porto, “First-order Raman effect in wurtzite-type crystals”, Phys. Rev. 181, 1351 (1969).
[41] J. M. Calleja and Manuel Cardona, “Resonant Raman scattering ZnO”, Phys. Rev. B 16, 3753 (1977).
[42] N. Ashkenov, B. N. Mbenkum, C. Bundesmann, V. Riede, M. Lorenz, D. Spemann, E. M. Kaidashev, A. Kasic, M. Schubert, and M.
Grundmann, “Infrard dielectric functions and phonon modes of high-quality ZnO films”, J. Appl. Phys. 93, 126 (2003).
[43] M. Schumm, M. Koerdel, S. Müller, H. Zutz, C. Ronning, J. Stehr, D.
M. Hofmann, and J. Geurts, “Structure impact of Mn implantation on ZnO”, New J. Phys. 10, 043004 (2008).
[44] K. A. Alim, V. A. Fonoberov, M. Shamsa, and A. A. Balandin, “Micro-Raman investigation of optical phonons in ZnO nanocrystals”, J. Appl.
Phys. 97, 124313 (2005).
[45] F. Decremps, J. Pellicer-Porres, A. M. Saitta, J. Chervin, and A. Polian,
132
“High-pressur Raman spectroscopy study of wurtzite ZnO”, Phys.
Rev. B 65, 092101 (2002).
[46] Y. J. Lin, C. L, Tsai, Y. M. Lu, and C. J. Liu, “Optical and electrical properties of undoped ZnO films”, J. Appl. Phys. 99, 093501 (2006).
[47] R.C. Rai, M. Guminiak, S Wilser, B. Cai, and M. L. Nakarmi,
“Elevated temperature dependence of energy band gap of ZnO thin films grown by e-beam deposition”, J. Appl. Phys. 111, 073511 (2012).
[48] A. A. Toropov, O. V. Nekrutkina, and T. V. Shubina, “Temperature-dependent exciton polariton photoluminescence in ZnO films”, Phys.
Rev. B 69, 165205 (2004).
[49] Jacques I. Pankove: Optical Processes in Semiconductors, Page 36 ~ 40 (1
st
edition, 1975).[50] S. J. Pearton, D. J. Norton, K. Ip, Y. W. Heo, and T. Steiner, “Recent progress in processing and properties of ZnO.”, Prog. Mater. Sci. 50, 293 (2005).
[51] Chennupati Jagadish and Stephen J. Pearton: Zinc Oxide Bulk, Thin
Films and Nanostructures Processing, Properties and Applications,
Page 1 ~ 20 (1st
edition, 2006).[52] J. Mass, P. Bhattacharya, and R. S. Katiyar, “Effect of high substrate temperature on Al-doped ZnO thin films grown by pulsed laser deposition”, Materials Science and Engineering B 103, 9 (2003).
[53] H. Huang, Y. Ou, S. Xu, G. Fang, M. Li, and X. Z. Zhao, “Properties of Dy-doped ZnO nanocrystalline thin films prepared by pulsed laser deposition”, Applied Surface Science 254, 2013 (2008).
[54] J. H. Kim, H. Kim, D. Kim, S. G. Yoon, and W. K. Choo, “Optical and magnetic properties of laser-deposited Co-doped ZnO thin films”, Solid State Commun 131, 677 (2004).
[55] B. C. Mohanty, Y. H. Jo, D. H. Yeon, and Y. S. Cho, “Stress-induced anomalous shift of optical band gap in ZnO:Al thin films”, Appl. Phys.
Lett. 95, 062103 (2009).
[56] B. E. Sernelius, K. F. Berggren, Z. C. Jin, and C. G. Granqvist, “Band-gap tailoring of Zno by means of heavy Al doping”, Phys. Rev. B 37, 10244 (1988).
[57] F. Lo, Y. Ting, K. Chou, T. Hsieh, C. Ye, Y. Hsu, M. Chern and H. Liu,
“Paramagnetic dysprosium-doped znic oxide thin films grown by pulsed-laser deposition”, J. Appl. Phys. 117, 213911 (2015).
[58] A. Atta, M. El-nahass, K. Elsabawy, M. El-raheem, A. Hassanien, A.
133
Alhuthali, A. Badawi, and A. Merazga, “Optical characteristics of transparent samarium oxide thin films deposition by the radio-frequency sputtering technique”, Pramana-J. Phys. 87, 72 (2016).
[59] H. Fujiwara: Spectroscopic Ellipsometry Principles and Applications (John Wiley & Sons, Ltd, 2003).
[60] G. A. Niklasson, O. G. Granqvist, and O. Hunderi, “Effective medium models for the optical properties of inhomogeneous materials”, Appl.
Opt. 20, 26 (1981).
[61] 葉秦維，摻雜鑭系元素(鏑, 釓)氧化鋅與單層二(硫, 硒)化鎢薄膜 的光譜性質研究，國立臺灣師範大學物理研究所碩士論文，104 年6 月。
[62] X. Zhang, X. Qiao, W. Shi, J. Wu, D. Jiang, and P. Tan, “Phonon and Raman scattering of two-dimensional transition metal dichalcogenides from monolayer, multilayer to bulk material”, Chem.
Soc. Rev. 44, 2757 (2015).
[63] D. Guzman and A. Strachan “Role of strain on electronic and mechanical response of semiconducting transition-metal dichalcogenide monolayer: An ab-initio study”, J. Appl. Phys. 115, 243701 (2014).
[64] A. Pawbake, M. Pawar, S. Jadkar, and D. Late, “Large area chemical vapor deposition of monolayer transition metal dichalcogenides and their temperature dependent Raman spectroscopy studies”, Nanoscale
8, 3008 (2016).
[65] X. Huang, Y. Gao, T. Yang, W. Ren, H. Cheng, and T. Lai,
“Quantitative analysis of temperature dependence of Raman shift of monolayer WS
2
”, Sci. Rep. 6, 32236 (2016).[66] H. Terrones, E. Corro, S. Feng, J. Poumirol, D. Rhodes, D. Smirnov, N. Pradhan, and Z. Lin, “New first order Raman-active modes in few layered transition metal dichalcogenides”, Sci. Rep. 4, 4215 (2014).
[67] 張雅婷，單層二(硫, 硒)化(鉬, 鎢)薄膜的光譜性質研究，國立臺 灣師範大學物理研究所碩士論文，105 年 7 月。
[68] A. Ramasubramaniam, “Large excitonic effects in monolayers of molybdenum and tungsten dichalcogenides”, Phys. Rev. B 86, 115409 (2012).
[69] J. Li, Y. Zhong and D. Zhang, “Exciton in monolayer transition metal dichalcogenides”, J. Phys.: Condens. Matter 27, 315301 (2015).
[70] M. Chhowalla, H. Shin, G. Eda, L. Li, K. Loh, and H. Zhang, “The chemistry of two-dimensional layered transition metal dichalcogenide
134
nanosheets”, Nature Chemistry 5, 263 (2013).
[71] G. Shim, K. Yoo, S. Seo, J. Shin, D. Jung, I. Kang, C. Ahn, B. Cho, and S. Choi, “Large-area single-layer MoSe
2
and its van der Waals Heterostructures”, ACS Nano 8, 6655 (2014).[72] B. Zhu, X. Chen, and X. Cui, “Exciton binding energy of monolayer WS
2
”, Sci. Rep. 5, 9218 (2015).[73] K. He, N. Kumar, L. Zhang, Z. Wang, K. Mak, H. Zhao, and J. Shan,
“Tightly bound excitons in monolayer WSe
2
”, Phys. Rev. Lett. 113, 026803 (2014).[74] Y. Tastumi, K. Ghalamkari, and R. Saito, “Laser energy dependence of valley polarization in transition-metal dichalcogenides”, Phys. Rev.
B 94, 235408 (2016).
[75] R. Bromley, R. Murray, and A. Yoffe, “The band structures of some transition metal dichalcogenides: III. Group VI A: trigonal prism materials”, J. Phys. C: Solid State Phys. 5, 759 (1972).
[76] A. Carvalho, R. Ribeiro, and A. Castro Neto, “Band nesting and the optical response of two-dimensional semiconducting transition metal dichalcogenides”, Phy. Rev. B 88, 115205 (2013).
[77] A. Kormányos, G. Burkard, M. Gmitra, J. Fabian, V. Zólyomi, N.
Drummond, and V. Fal’ko, “k‧p theory for two-dimenional transition metal dichalcogenide semiconductors”, 2D Matt. 2, 022001 (2015).
[78] L. Viña, S. Logothetidis, and M. Cardona, “Temperature dependence of the dielectric function of germanium”, Phys. Rev. B 30, 1979 (1984).
[79] D. Kozawa, R. Kumar, A. Carvalho, K. Amara, W. Zhao, S. Wang, M.
Toh, R. Ribeiro, A. Castro Neto, K. Mastuda, and G. Eda,
“Photocarrier relaxation pathway in two-dimensional semiconducting transition metal dichalcogenides”, Nature Communications 5, 4543 (2014).
[80] K. O’Donnell and X. Chen, “Temperature dependence of semiconductor band gaps”, Appl. Phys. Lett. 58, 2924 (1991).
[81] Y. Varshni, “Temperature dependence of the energy gap in semiconductors”, Physica 34, 149 (1967).
[82] G. Plechinger, P. Nagler, J. Kraus, N. Paradiso, C. Strunk, C. Schüller, and T. Korn, “Identification of exciton, trions, and biexcitons in single-layer WS
2
”, Phys. Status Solidi RRL 9, 457 (2015).[83] T. Korn, S. Heydrich, M. Hirmer, J. Schmutzler, and C. Schüller,
“Low-temperature photocarrier dynamics in monolayer MoS
2
”, Appl.135
Phys. Lett. 99, 102109 (2011).
[84] Z. He, Y. Sheng, Y. Rong, G. Lee, and J. Warner, “Layer-dependent modulation of tungsten disulfide photoluminescence by lateral electric fields”, ACS Nano 9, 2740 (2015).
[85] A. Mitioglu, K. Galkowski, A. Surrente, L. Klopotowski, A. Kis, D.
Maude, and P. Plochocka, “Magnetoexcitons in large area CVD-grown monolayer MoS
2
and MoSe2
on sapphire”, Phys. Rev. B 93, 165412 (2016).[86] B. Peng, H. Zhang, H. Shao, Y. Xu, X. Zhang, and H. Zhu, “Thermal conductivity of monolayer MoS
2
, MoSe2
, andWS2
: interplay of mass effect, interatomic bonding and anharmonicity”, RSC Adv. 6, 5767 (2016).[87] P. Norouzzadeh and D. Singh, “Thermal conductivity of single-layer WSe