臺灣博碩士論文加值系統

本論文利用熱化學氣相沉積系統在藍寶石基板上成長單層二硒化鎢，由光學顯微鏡及掃描式電子顯微鏡觀察樣品的表面型態，接著利用原子力顯微鏡和拉曼散射光譜確認樣品及厚度，再用X光電子能譜儀確認成分比例. 由於二硒化鎢從塊材到單層結構時將會由間接能隙轉變為直接能隙，因此我們利用光致發光進一步證實樣品為單層結構. 變溫光致發光在室溫中能觀察到自由激子的訊號，在低溫中因為載子凍結效應，能觀察到侷限激子的訊號. 電晶體的電壓-電流特性曲線以狄拉克點作為分界電子電洞的工作區，藉其判斷材料的半導體特性. 最後將二硒化鎢成功製作成高光電導及高光響應的光感測元件，以雷射波長405、532、633及808 nm進行光電流之量測，不同波長雷射的光子能量產生的光電流及光吸收率也不同，測得以405 nm波長的光電導及光響應最好，再以405 nm雷射以不同功率進行量測量測並得知光電導會依照功率上升而上升，光響應結果則是相反，主要歸因於功率越高載子活期變短，導致低功率的光響應會較好.

In this thesis, we used chemical vapor deposition method to synthesize monolayer WSe2 on Sapphire Substrates, first of all, we observed the surface of WSe2 by optical microscope and scanning electron microscopy (SEM), second, we could confirm the thickness of WSe2 by atomic force microscopy (AFM) and Raman spectroscopy, third, we could affirm the band gap structure, quality and quantity characteristics of WSe2 by using photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). In this research, we made a further verification that the monolayer was a single layer structure when we used Photoluminescence (PL) which meant that band structure would change from indirect bandgap to direct bandgap when WSe2 transformed from bulk material to single layer structure. Excitonic properties of monolayer WSe2 of localized exciton (LX) emission and free exciton (FX) emission were observed throughout temperature dependent photoluminescence in different temperature, we could observe localized exciton (LX) emission by freezing effect of the charge carrier when temperature dependent photoluminescence spectra in low temperature. We determined the semiconductor material properties by the voltage-current characteristic of the transistor of the Dirac point position. Photocurrent of WSe2 was measured with different wavelength of laser sources by metal-semiconductor-metal photoconductive detectors. Different photon energies and absorbance occurred since different wavelength of laser source, which were 405, 532, 632.8 and 808 nm. Finally, there were the best result included the photoconductivity and photoresponse by measuring 405 nm laser. The more power increased, the more photoconductivity rose varied with the power and the photoresponse was opposite to photoconductivity because short carrier lifetime with high power would lead to better photoresponse with low power.

中文摘要 -----------------------------------------------------------------------------------
I
英文摘要 -----------------------------------------------------------------------------------
II
致謝 -----------------------------------------------------------------------------------------
III
目錄 -----------------------------------------------------------------------------------------
IV
圖索引 --------------------------------------------------------------------------------------
VII
表索引 --------------------------------------------------------------------------------------
X
第一章 緒論 -------------------------------------------------------------------------------
1
1.1 二維半導體材料 ----------------------------------------------------------------
1
1.2 過渡金屬硫化物 ----------------------------------------------------------------
2
1.2.1 二硒化鎢 --------------------------------------------------------------
4
1.2.2 合成方法 --------------------------------------------------------------
5
1.3 光感測器 -------------------------------------------------------------------------
6
1.3.1 光電導機制-----------------------------------------------------------
1.3.1.1 光電效應--------------------------------------------------------
1.3.1.2 光電導效應-----------------------------------------------------
1.3.1.3 光熱電效應-----------------------------------------------------
1.3.2 光電導率 --------------------------------------------------------------
7
7
89 10
1.3.3 量子效率與光響應度-----------------------------------------------
1.3.4 歸一化光電流增益--------------------------------------------------
11
12
1.4 狄拉克點 -------------------------------------------------------------------------
1.5 研究背景及動機 ----------------------------------------------------------------
13 14
第二章 實驗方法與設備 ---------------------------------------------------------------
15
2.1 實驗流程圖 ----------------------------------------------------------------------
15
2.2 晶體成長與製備 ----------------------------------------------------------------
16
V
2.2.1 基板製備 --------------------------------------------------------------
2.2.2 二硒化鎢成長機制 ----------------------------------------------
2.2.3 二硒化鎢成長方法-----------------------------------------------
16
17
19
2.3 分析量測儀器 -------------------------------------------------------------------
21
2.3.1 拉曼散射儀-----------------------------------------------------------
2.3.2 光激發螢光光譜量測-----------------------------------------------
2.3.2.1 光激發螢光光譜原理 -----------------------------------------
2.3.2.2 顯微-光激發螢光(μ-PL) --------------------------------
2.3.2.3 光激發螢光光譜儀器架設流程------------------------
2.3.3 掃描式電子顯微鏡--------------------------------------------------
2.3.4 穿透式電子顯微鏡--------------------------------------------------
2.3.5 原子力顯微鏡--------------------------------------------------------
2.3.6 X光光電子能譜儀--------------------------------------------------
2.3.7 半導體特性量測系統-----------------------------------------------
2.4 場效應電晶體量測方法 -------------------------------------------------------
2.5 光感測器樣品製作與量測方法---------------------------------------------
21 24 24 27 28 30 32 33 35 36 37 38
第三章 結果與討論 ---------------------------------------------------------------------
40
3.1 WSe2表面型態分析-----------------------------------------------------------
40
3.1.1 掃描式電子顯微鏡影像圖-----------------------------------------
40
3.1.2 光學顯微鏡影像圖 -------------------------------------------------
41
3.1.3 穿透式電子顯微鏡影像圖-----------------------------------------
42
3.1.4 原子力顯微鏡影像圖-----------------------------------------------
43
3.2 成份及特性分析---------------------------------------------------------------
44
3.2.1 拉曼光譜 ----------------------------------------------------------------
44
VI
3.2.2 光激發螢光光譜量測 ------------------------------------------
46
3.2.2.1 顯微-光激發螢光量測------------------------------------------
46
3.2.2.2 低溫光激發螢光量測-----------------------------------------
47
3.2.3 X光光電子能譜圖--------------------------------------------------
51
3.2.4 半導體特性量測-----------------------------------------------------
53
3.3 光感測器------------------------------------------------------------------------
56
3.3.1 光感測器之光電流量測--------------------------------------------
56
3.3.2 光電導率 --------------------------------------------------------------
60
3.3.3 歸一化光響應度-----------------------------------------------------
63
3.4 光感測器之特性分析 ----------------------------------------------------------
66
3.4.1 M-S-M光電導元件架構--------------------------------------------
66
3.4.2 WSe2光響應度分析-------------------------------------------------
67
3.4.3 光電流及吸光度-----------------------------------------------------
69
第四章 結論 -------------------------------------------------------------------------------
71
第五章 參考文獻------------------------------------------------------------------------
73

[1] K. F. Mak and J. Shan, “Photonics and optoelectronics of 2D semiconductor transition metal dichalcogenides,” Nature Photon., vol. 10, no. 4, pp. 216-226, 2016.
[2] H. Fang, S. Chuang, T. C. Chang, K. Takei, T. Takahashi, and A. Javey, “High-performance single layered WSe2 p-FETs with chemically doped contacts,” Nano Lett., vol. 12, no. 7, pp. 3788-3792, 2012.
[3] K. S. Novoselov, A. K. Geim, S. V. Morozov, D, Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science, vol. 306, pp. 666-669, 2004.
[4] F. Bonaccorso, Z. Sun, T. Hasan, and A. C. Ferrari, “Graphene photonics and optoelectronics,” Nature Photon., vol. 4, pp. 611-622, 2010.
[5] X. Li, Y. Zhu, W. Cai, M. Borysiak, B. Han, D. Chen, R. D. Piner, L. Colomba, and R. S. Ruoff, “Transfer of large-area graphene films for high-performance transparent conductive electrodes,” Nano Lett., vol. 9, pp. 4359-4363, 2009.
[6] Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, and R. S. Ruoff, “Graphene and graphene oxide: Synthesis, properties, and applications,” Adv. Mater., vol. 22, pp. 3906-3924, 2010.
[7] D. Jariwala, V. K. Sangwan, L. J. Lauhon, T. J. Marks, and M. C. Hersam, “Emerging device applications for semiconducting two-dimensional transition metal dichalcogenides,” ACS Nano, vol. 8, pp. 1102-1120, 2014.
[8] RadisavljevicB, RadenovicA, BrivioJ, GiacomettiV, and KisA, “Single-layer MoS2 transistors,” Nat Nano., vol. 6, no. 3, pp. 147-150, 2011.
[9] W. J. Yu, Y. Liu, H. Zhou, A. Yin, Z. Li, Y. Huang, and X. Duan, “Highly efficient gate-tunable photocurrent generation in vertical heterostructures of layered materials,” Nat Nano., vol. 8, no. 12, pp. 952-958, 2013.
[10] W. Jaegermann and H. Tributsch, “Interfacial properties of semiconducting transition metal chalcogenides,” Progress Surf. Sci., vol. 29, pp. 1-167, 1988.
[11] H. Li, J. Wu, Z. Yin, and H. Zhang, “Preparation and applications of mechanically exfoliated single-layer and multilayer MoS2 and WSe2 nanosheets,” Acc. Chem. Res., vol. 47, pp. 1067-1075, 2014.
[12] C. Feng, L. Huang, Z. Guo, and H. Liu, “Synthesis of tungsten disulfide (WS2) nanoflakes for lithium ion battery application,” Electrochem. Commun., vol. 9, pp.119-122, 2007.
[13] G. Prasad, and O. N. Srivastava, “The high-efficiency (17.1%) WSe2 photo-electrochemical solar cell,” J. Phys. D: Appl. Phys., vol. 21, pp.1028-1030, 1988.
[14] K. Å. V. Anderson, S. E. Kaelsson, and N. Ohmae, “Morphologies of rf sputter-deposited solid lubricants,” Vacuum, vol. 27, pp. 213-412, 1997.
[15] A. Splendiani, L. Sun, Y. Zhang, T. Li, J. Kim, C. Y. Chim, G. Galli, and F. Wang, “Emerging photoluminescence in monolayer MoS2,” Nano Lett., vol. 10, pp. 1271-1275, 2010.
[16] K. F. Mak, C. Lee, J. Hone, J. Shan, and T. F. Heinz, “Atomically thin MoS2: A new direct-gap semiconductor,” Phys. Rev. Lett., vol. 105, pp. 136805-1-136805-4, 2010.
[17] X. Chia, A. Ambrosi, Z. Sofer, J. Luxa, and M. Pumera, “Catalytic and charge transfer properties of transition metal dichalcogenides arising from electrochemical pretreatment,” ACS Nano, vol. 9, pp. 5164-5179, 2015.
[18] A. Winchester, S. Ghosh, S. Feng, A. L. Elias, T. Mallouk, M. Terrones, and S. Talapatra, “Electrochemical characterization of liquid phase exfoliated two dimensional layers of molybdenum disulfide,” ACS Appl. Mater. Interfaces., vol. 6, pp. 2125-2130, 2014.
[19] C. Feng, J. Ma, H. Li, R. Zheng, Z. Guo, and H. Liu, “Synthesis of molybdenum disulfide (MoS2) for lithium ion battery applications,” Mater. Res. Bull., vol. 44, pp. 1811-1815, 2009.
[20] P. Tonndorf, R. Schmidt, P. Böttger, X. Zhang, J. Börner, A. Liebig, M. Albrecht, C. Kloc, O. Gordan, D. R. T. Zahn, S. Michaelis de Vasconcellos, and R. Bratschitsch, “Photoluminescence emission and Raman response of monolayer MoS2, MoSe2, and WSe2,” Opt. Express., vol. 21, no. 4, pp. 4908-4916, 2013.
[21] N. Pradhan, D. Rhodes, S. Memaran, J. Poumirol, D. Smirnov, S. Talapatra, S. Feng, N. Perea-Lopez, A. Elias, and M. Terrones, “Hall and field-effect mobilities in few layered p-WSe2 field-effect transistors,” Sci. Rep., vol. 5, pp. 8979-1-8979-8, 2015.
[22] B. Liu, Y. Ma, A. Zhang, L. Chen, A. N. Abbas, Y. Liu, C. Shen, H. Wan, and C. Zhou, “High-performance WSe2 field-effect transistors via controlled formation of in-plane heterojunctions,” ACS Nano, vol. 10, pp. 5153-5160, 2016.
[23] Z. Zheng, T. Zhang, J. Yao, Y. Zhang, J. Xu, and G. Yang, “Flexible, transparent and ultra-broadband photodetector based on large-area WSe2 film for wearable devices,” Nanotechnol., vol. 27, no. 22, pp. 225501-1-225501-11, 2016.
[24] A. Krotkus, “Semiconductors for terahertz photonics applications,” J. Phys. D: Appl. Phys., vol. 43, no. 27, p. 273001, 2010.
[25] H. S. Loka, S. D. Benjamin, and P. W. Smith, “Optical characterization of low-temperature-grown GaAs for ultrafast all-optical switching devices,” IEEE J. Sel. Top. Quant. Electron., vol. 34, no. 8, pp. 1426-1437, 1998.
[26] Y. Shen, P. Upadhya, E. Linfield, H. Beere, and A. Davies, “Ultrabroadband terahertz radiation from low-temperature-grown GaAs photoconductive emitters,” Appl. Phys. Lett., vol. 83, no. 15, pp. 3117-3119, 2003.
[27] D. J. Groenendijk, M. Buscema, G. A. Steele, S. M. de Vasconcellos, R. Bratschitsch, H. S. J. van der Zant, and A. Castellanos-Gomez, “Photovoltaic and photothermoelectric effect in a double-gated WSe2 device,” Nano Lett., vol. 14, no. 10, pp. 5846-5852, 2014.
[28] L. Chen, B. Liu, A. N. Abbas, Y. Ma, X. Fang, Y. Liu, and C. Zhou, “Screw-dislocation-driven growth of two-dimensional few-layer and pyramid-like WSe2 by sulfur-assisted chemical vapor deposition,” ACS Nano, vol. 8, no. 11, pp. 11543-11551, 2014.
[29] M. Tosun, S. Chuang, H. Fang, A. B. Sachid, M. Hettick, Y. Lin, Y. Zeng, and A. Javey, “High-gain inverters based on WSe2 complementary field-effect transistors,” ACS nano, vol. 8, no. 5, pp. 4948-4953, 2014.
[30] J. S. Ross, P. Klement, A. M. Jones, N. J. Ghimire, J. Yan, D. Mandrus, T. Taniguchi, K. Watanabe, K. Kitamura, and W. Yao, “Electrically tunable excitonic light-emitting diodes based on monolayer WSe2 pn junctions,” Nature Nanotech., vol. 9, no. 4, pp. 268-272, 2014.
[31] A. K. Rai, R. S. Bhattacharya, J. S. Zabinski, and K. Miyoshi, “A comparison of the wear life of as-deposited and ion-irradiated WS2 coating,” Surf. Coat. Technol., vol. 92, pp. 120-128, 1997.
[32] A. Jäger-Waldau, M. Ch. Lux-Steiner, G. Jäger-Waldau, and E. Bucher, “WS2 thin films prepared by sulphurization,” Appl. Surf. Sci. vol.70-71, pp. 731-736, 1993.
[33] Q. H. Wang, K. Kalantar-Zadeh, A. Kis, J. N. Coleman, and M. S. Strano, “Electronics and optoelectronics of two-dimensional transition metal dichalcogenides,” Nature Nanotech., vol. 7, pp. 699-712, 2012.
[34] J. N. Coleman, M. Lotya, A. O’Neill, S. D. Bergin, P. J. King, U. Khan, K. Young, A. Gaucher, S. De, and R. J. Smith, “Two-dimensional nanosheets produced by liquid exfoliation of layered materials,” Science, vol. 331, no. 6017, pp. 568-571, 2011.
[35] G. Eda, H. Yamaguchi, D. Voiry, T. Fujita, M. Chen, and M. Chhowalla, “Photoluminescence from chemically exfoliated MoS2,” Nano Lett., vol. 11, no. 12, pp. 5111-5116, 2011.
[36] Y. H. Lee, X. Q. Zhang, W. Zhang, M. T. Chang, C. T. Lin, K. D. Chang, Y. C. Yu, J. T. W. Wang, C. S. Chang, and L. J. Li, “Synthesis of large‐area MoS2 atomic layers with chemical vapor deposition,” Adv. Mater., vol. 24, no. 17, pp. 2320-2325, 2012.
[37] Y. Zhan, Z. Liu, S. Najmaei, P. M. Ajayan, and J. Lou, “Large‐area vapor‐phase growth and characterization of MoS2 atomic layers on a SiO2 substrate,” Small, vol. 8, no. 7, pp. 966-971, 2012.
[38] K.-K. Liu, W. Zhang, Y.-H. Lee, Y.-C. Lin, M.-T. Chang, C.-Y. Su, C.-S. Chang, H. Li, Y. Shi, and H. Zhang, “Growth of large-area and highly crystalline MoS2 thin layers on insulating substrates,” Nano Lett., vol. 12, no. 3, pp. 1538-1544, 2012.
[39] M. Fontana, T. Deppe, A. K. Boyd, M. Rinzan, A. Y. Liu, M. Paranjape, and P. Barbara, “Electron-hole transport and photovoltaic effect in gated MoS2 Schottky junctions,” Sci. Rep., vol. 3, pp. 1634-1-1634-5, 2012.
[40] M. Buscema, M. Barkelid, V. Zwiller, H. S. J. van der Zant, G. A. Steele, and A. Castellanos-Gomez, “Large and tunable photothermoelectric effect in single-layer MoS2,” Nano Lett., vol. 13, pp. 358-363, 2013.
[41] Y. Zhang, H. Li, L. Wang, H. Wang, X. Xie, S. L. Zhang, R. Liu, and Z. J. Qiu, “Photothermoelectric and photovoltaic effects both present in MoS2,” Sci. Rep., vol. 5, pp.7938-1-7938-7, 2015.
[42] M. M. Furchi, D. K. Polyushkin, A. Pospischil, and T. Mueller, “Mechanisms of photoconductivity in atomically thin MoS2,” Nano Lett., vol. 14, no. 11, pp. 6165-6170, 2014.
[43] M. Buscema, J. O. Island, D. J. Groenendijk, S. I. Blanter, G. A. Steele, H. S. J. van der Zant, and A. Castellanos-Gomez, “Photocurrent generation with two-dimensional van der Waals semiconductors,” Chem. Soc. Rev., vol. 44, pp. 3691-3718, 2015.
[44] M. Buscema, M. Barkelid, V. Zwiller, H. S. J. van der Zant, G. A. Steele, and A. Castellanos-Gomez, “Large and tunable photothermoelectric effect in single-layer MoS2,” Nano Lett., vol. 13, pp. 358-363, 2013.
[45] B. C. St-Antoine, D. Ménard, and R. Martel, “Photothermoelectric effects in single-walled carbon nanotube films: Reinterpreting scanning photocurrent experiments,” Nano Res., vol. 5, no. 2, pp. 73-81, 2012.
[46] M. Barkelid and V. Zwiller, “Photocurrent generation in semiconducting and metallic carbon nanotubes,” Nat Photon., vol. 8, no. 1, pp. 47-51, 2014.
[47] J. Hass, W. A. de Heer, and E. H. Conrad, “The growth and morphology of epitaxial multilayer graphene,” J. Phys., vol. 20, pp. 323202-323228, 2008.
[48] D. S. L. Abergel, V. Apalkov, J. Berashevich, K. Ziegler, and T. Chakraborty, “Properties of graphene: a theoretical perspective,” Adv. in Phys., vol. 59, pp. 261-482, 2010.
[49] S. Yugo, T. Kanai, T. Kimura, and T. Muto, “Generation of diamond nuclei by electric field in plasma chemical vapor deposition,” Appl. Phys. Lett., vol. 58, no. 10, pp. 1036-1038, 1991.
[50] A. Bablich, S. Kataria, and M. C. Lemme, “Graphene and two-dimensional materials for optoelectronic applications,” Electronics, vol. 5, no. 1, p. 13, 2016.
[51] J. R. Szczech and S. Jin, “Epitaxially-hyperbranched FeSi nanowires exhibiting merohedral twinning,” J. Mater. Chem., vol. 20, no. 7, pp. 1375-1382, 2010.
[52] L. Niu, K. Li, H. Zhen, Y. S. Chui, W. Zhang, F. Yan, and Z. Zheng, “Salt‐assisted high‐throughput synthesis of single‐and few‐layer transition metal dichalcogenides and their application in organic solar cells,” Small, vol. 10, no. 22, pp. 4651-4657, 2014.
[53] P. Tonndorf, R. Schmidt, P. Böttger, X. Zhang, J. Börner, A. Liebig, M. Albrecht, C. Kloc, O. Gordan, D. R. T. Zahn, S. Michaelis de Vasconcellos, and R. Bratschitsch, “Photoluminescence emission and Raman response of monolayer MoS2, MoSe2, and WSe2,” Opt. Express., vol. 21, no. 4, pp. 4908-4916, 2013.
[54] W. Zhao, Z. Ghorannevis, K. K. Amara, J. R. Pang, M. Toh, X. Zhang, C. Kloc, P. H. Tan, and G. Eda, “Lattice dynamics in mono-and few-layer sheets of WS2 and WSe2,” Nanoscale, vol. 5, no. 20, pp. 9677-9683, 2013.
[55] H. Shi, R. Yan, S. Bertolazzi, J. Brivio, B. Gao, A. Kis, D. Jena, H. G. Xing, and L. Huang, “Exciton dynamics in suspended monolayer and few-layer MoS2 2D crystals,” ACS Nano, vol. 7, no. 2, pp. 1072-1080, 2013.
[56] J. Huang, T. B. Hoang, and M. H. Mikkelsen, “Probing the origin of excitonic states in monolayer WSe2,” Sci. Rep., vol. 6, p. 22414, 2016.
[57] G. Wang, L. Bouet, D. Lagarde, M. Vidal, A. Balocchi, T. Amand, X. Marie, and B. Urbaszek, “Valley dynamics probed through charged and neutral exciton emission in monolayer WSe2,” Phys. Rev., vol. 90, no. 7, p. 075413, 2014.
[58] T. Yan, X. Qiao, X. Liu, P. Tan, and X. Zhang, “Photoluminescence properties and exciton dynamics in monolayer WSe2,” Appl. Phys. Lett., vol. 105, no. 10, p. 101901, 2014.
[59] Y. P. Varshni, “Temperature dependence of the energy gap in semiconductors,” Physica, vol. 34, pp. 149-154, 1967.
[60] A. Arora, M. Koperski, K. Nogajewski, J. Marcus, C. Faugeras, and M. Potemski, “Excitonic resonances in thin films of WSe2: from monolayer to bulk material,” Nanoscale, vol. 7, no. 23, pp. 10421-10429, 2015.
[61] Y. Chen, J. Xi, D. O. Dumcenco, Z. Liu, K. Suenaga, D. Wang, Z. Shuai, Y. S. Huang, and L. Xie, “Tunable band gap photoluminescence from atomically thin transition-metal dichalcogenide alloys,” ACS Nano, vol. 7, pp. 4610-4616, 2013.
[62] Z. Yin, H. Li, L. Jiang, Y. Shi, Y. Sun, G. Lu, Q. Zhang, X. Chen, and H. Zhang, “Single-layer MoS2 phototransistors,” ACS Nano, vol. 6, pp. 74-80, 2012.
[63] H. M. Li, D. Y. Lee, M. S. Choi, D. Qu, X. Liu, C. H. Ra, and W. J. Yoo, “Metal-semiconductor barrier modulation for high photoresponse in transition metal dichalcogenide field effect transistors,” Sci. Rep., vol. 4, pp. 4041-1-4041-7, 2014.
[64] W. Zhang, M.-H. Chiu, C.-H. Chen, W. Chen, L.-J. Li, and A. T. S. Wee, “Role of metal contacts in high-performance phototransistors based on WSe2 monolayers,” ACS Nano, vol. 8, no. 8, pp. 8653-8661, 2014.
[65] N. Dong, Y. Li, Y. Feng, S. Zhang, X. Zhang, C. Chang, J. Fan, L. Zhang, and J. Wang, “Optical limiting and theoretical modelling of layered transition metal dichalcogenide nanosheets,” Sci. Rep., vol. 5, pp. 14646-1-14646-10, 2015.