本研究所探討的主題是在低溫環境下利用原子層沉積系統進行高品質氧化鋅和氧化鎂鋅薄膜，藉由原子層沉積系統的均勻性，製作氧化鎂鋅/氧化鋅異質結構。本實驗室透過原子層沉積系統成長氧化鋅和氧化鎂鋅薄膜，進一步去分析不同基板溫度下薄膜的結晶性、霍爾量測和光學能隙。因考慮到氧化鋅層須具有(002)結晶特性及低電子濃度，所以採用結晶性較佳之條件成長氧化鋅薄膜，再經過氧氣退火填補氧缺陷，使薄膜濃度下降至10^17cm-3及提升其薄膜結晶特性。相對於氧化鋅層和氧化鎂鋅層的片濃度和電子遷移率，異質結構的片濃度和電子遷移率都有明顯的提升，可以解釋二維電子氣的存在。一般自由載子的濃度和載子遷移率容易受溫度的影響而變動；從變溫霍爾量測可以得知，氧化鎂鋅/氧化鋅異質結構在溫度180K到300K區間，片濃度和電子遷移率不隨著溫度改變而變化，所以由這個現象可以說明電子具有二維特性；也由電容-電壓量測得到濃度峰值的位置與結構中氧化鎂鋅層厚度符合，再次驗證二維電子氣的存在。

The topic of this research is to investigate high quality ZnO and MgZnO thin film deposited at low temperature by Atomic Layer Deposition(ALD). Because ALD have Large area uniformity ,we fabricate MgZnO/ZnO heterostructure by ALD. The research would analyze the crystallinity、Hall-effect analysis and optical energy gap (Eopt) of ALD’s film. Because we considered the ZnO layer must have (002) crystallization signal and the low electron concentration, so film growth in high temperature(350℃) is used. Electron concentration decreases to 10^17cm-3, and also the crystallinity properties is improved when annealed in O2 atmosphere. Compared to the sheet concentration and mobility of ZnO and MgZnO film, the sheet concentration and mobility of heterostructure increase rapidly. Free electron at high temperature is easily influenced by crystal lattice scattering. Both carrier concentration and mobility are temperature independent at 180K to 300K, indicating the formation of 2DEG at the MgZnO/ZnO interface. The carrier concentration versus depth curve obtained from capacitance-voltage measurement. Electron accumulation with a spike sharp was clearly observed at 100.7nm, which mstches the thickness of MgZnO in the heterostructure; these features demonstrate 2DEG formation at the interface.

Chapter1
[1] S. J. Pearton, D. P. Norton, K. Ip, Y. W. Heo, and T. Steiner, “Recent progress in processing and properties of ZnO,” Prog. Mater. Sci., vol. 50, pp. 293–340, 2005.
[2] D. C. Look, J. W. Hemsky, and J. R. Sizelove, “Residual Native Shallow Donor in ZnO,” Phys. Rev. Lett., Vol.82, pp.2552-2555, 1999.
[3] A. Janotti and C. G. Van de Walle, “Oxygen vacancies in ZnO,” Appl. Phys. Lett., Vol.87, pp.122102-1-122102-3, 2005.
[4] C. G. Van de Walle, “Hydrogen as a Cause of Doping in Zinc Oxide,” Phys. Rev. Lett., Vol.85, pp.1012-1015, 2000.
[5] W. Water and S. Y. Chu, “Physical and structural properties of ZnO sputtered films,” Mater. Lett., Vol. 55, pp.67-72, 2002.
[6] S. Y. Chu, W. Water, and J. T. Liaw, “Influence of postdeposition annealing on the properties of ZnO films prepared by RF magnetron sputtering,” J. Eur. Cera. Soc., Vol. 23, pp. 1593-159, 2003.
[7]J. D. Albrecht, P. P. Ruden, S. Limpijumnong, W. R. L. Lambrecht, and K. F. Brennan, “High filed electron transport properties of bulk ZnO”, J. Appl. Phys., Vol. 86, pp. 6864-6867, 1999.
[8] A. Ohtomo, M. Kawasaki, I. Ohkubo, H. Koinuma, T. Yasuda, and Y. Segawa, “Structure and optical properties of ZnO/Mg0.2Zn0.8O superlattices”, Appl. Phys. Lett., Vol. 75, pp. 980-982, 1999.
[9]A. N. Westmeyer, S. Mahajan, K. K. Bajaj, J. Y. Lin, H. X. Jiang, D. D. Koleske, and R. T. Senger, “Determination of energy-band offsets between GaN and AlN using excition luminescence transition in AlGaN alloys”, J. Appl. Phys., Vol. 99, pp. 013705-1-013705-4, 2006.
[10]A. Ohtomo, M. Kawasaki, T. Koida, K. Masubuchi, and H. Koinuma, “MgxZn1−xO as a II–VI widegap semiconductor alloy”, Appl. Phys. Lett., Vol. 72, pp. 2466-2468, 1998.
[11] R. Schmidt, B. Rheinländer, M. Schubert, D. Spemann, T. Butz, J. Lenzner, E.M. Kaidashev, M. Lorenz, A. Rahm, H.C. Semmelhack, and M. Grundmann, “Dielectric functions (1 to 5 eV) of wurtzite MgxZn1−xO (x ⩽ 0.29) thin films”, Appl. Phys. Lett., Vol. 82, pp. 2260-2262, 2003.
[12] H. Tampo, H. Shibata, K. Matsubara, A. Yamada, P. Fons, S. Niki, M. Yamagata, and H. Kanie, “Two-dimensional electron gas in Zn polar ZnMgO/ZnO heterostructures grown by radical source molecular beam epitaxy”, Appl. Phys. Lett., Vol. 89, pp. 132113-1-132113-3, 2006.
[13] A. Tsukazaki, A. Ohtomo, M. Nakano, and M. Kawasaki, “Photoinduced insulator-to-metal transition in ZnO/Mg0.15Zn0.85O heterostructures”, Appl. Phys. Lett., Vol. 92, pp. 052105-1-052105-3, 2008.
[14] Huai-An Chin, I-Chun Cheng, Chih-I Huang, Yuh-Renn Wu, Wen-Sen Lu, Wei-Li Lee, Jian Z. Chen, Kuo-Chuang Chiu and Tzer-Shen Lin, “Two dimensional electron gases in polycrystalline MgZnO/ZnO heterostructures grown by rf-sputtering process”, Appl. Phys. Lett., Vol. 108, pp. 054503-1-054503-4, 2010.
Chapter2
[1]David M King, Samantha I Johnson, Jianhua Li, Xiaohua Du, Xinhua Liang and AlanW Weimer, “Atomic layer deposition of quantum-confined ZnO nanostructures”, Nanotechnology, Vol. 20, pp. 195401, 2009.
[2]Sang Jik Kwon, “Effect of precursor-pulse on properties of Al-doped ZnO films grown by atomic layer deposition”, Jpn. J. Appl. Phys, Vol. 44, pp. 1062-1066, 2005.
[3]A. W. Ott, J. W. Johnson, S. M. George, “Al2O3 thin film growth on
Si(100) using binary reaction sequence chemistry”, Thin Solid Films, Vol. 292, pp. 135–144, 1997.
[4]L. Wachnicki, T. Krajewski, G. Luka ,B. Withowski, B. Kowalski, K. Kopalko, J. Z. Domagala, M. Godlewski, and E. Guziewicz, “Monocrystalline zinc films grown by atomic layer deposition”, Thin Solid Films, Vol. 518, pp. 4556–4559, 2010.
[5]B. B. Burton, D. N. Goldstein, and S. M. George, “Atomic Layer Deposition of MgO Using Bis(ethylcyclopentadienyl)magnesium and H2O”, J. Phys.Chm. C, 113, pp. 1939-1946, 2009.
[6]Markku Leskela, and Mikko Ritala, “Atomic layer deposition (ALD) : from precursors to thin film structures”, Thin Solid Films, Vol. 409, pp. 138–146, 2002.
[7] T. To¨rndahl, C. Platzer-Bjo¨rkman, J. Kessler, and M. Edoff, “Atomic Layer Deposition of Zn1-xMgxO Buffer Layers for Cu(In,Ga)Se2 Solar Cells”, Prog. Photovolt: Res. Appl., 15, pp. 225-235, 2005.
[8] Ü. Özgür, Ya. I. Alivov, C. Liu, A. Teke, M. A. Reshchikov, S.
Doğan, V. Avrutin,S.-J. Cho, and H. Morkoçd, “A comprehensive review of ZnO materials and devices”, J. Appl.Phys, Vol. 98, pp. 041301-1-041301-103, 2005.
[9] S. J. Pearton, D. P. Norton, K. Ip, Y. W. Heo, and T. Steiner, “Recent progress in processing and properties of ZnO,” Prog. Mater. Sci., Vol. 50, pp. 293–340, 2005.
[10] D. C. Look, J. W. Hemsky, and J. R. Sizelove, “Residual Native Shallow Donor in ZnO,” Phys. Rev. Lett., Vol. 82, pp.2552-2555, 1999.
[11] W. Yang, S. S. Hullavarad, B. Nagarai, I. Takeuchi, R. P. Sharma, and T. Venkatesan, “Compositionally-tuned epitaxial cubic MgxZn1-xO on Si(100) for deep ultraviolet photodetectors”, Appl. Phys. Lett., Vol. 98, pp. 03424-3426, 2005.
[12] W. C. Mitchel, G. J. Brown, Ikai Lo, Said Elhamri, Mohamed Ahoujja, K. Ravindran, R. S. Newrock, Manijeh Razeghi, and Xiaguang He, “Interface roughness scattering in thin, undoped GaInP/GaAs quantum wells ”, Appl. Phys. Lett., Vol. 65, pp. 1578-1580, 1994.
[13]C. Weisbuch and B. Vinter, “Quantum semiconductor structures, fundamentals and application”, p. 49 (Academic Press, Ins., San Diego, 1991)
[14] O. Ambacher, B. Foutz, J. Smart, J. R.Shealy, N. G. Weimann, K.
Chu, M.Murphy, A. J. Sierakowski, W. J. Schaff, L. F. Eastman, R. Dimitrov, A. Mitchell, and M. Stutzmann, “Two dimensional electron gases induced by spontaneous and piezoelectric polarization in undoped and doped AlGaN / GaN heterostructures”, J. Appl. Phys., Vol. 87, pp. 334-344, 2000.
[15] J. P. Ibbetson, P. T. Fini, K. D. Ness, S. P. DenBaars, J. S. Speck, and U. K. Mishra, “Polarization effects, surface states, and the source of electrons in AlGaN/GaN heterostructure field effect transistors,”Appl. Phys. Lett., Vol. 77, No. 2, pp. 250-252, 2000.
[16] M. Nakano, A. Tsukazaki, K. Ueno, R. Y. Gunji, A. Ohtomo, T. Fukumura and M. Kawasaki, “Spatial distribution of two-dimensional electron gas in a ZnO/MgZnO heterostructure probed with a conducting polymer Schottky contact”, Appl. Phys. Lett., Vol. 96, pp. 052116-1-052116-3, 2010.
Chapter3
[1] M. Nakano, A. Tsukazaki, K. Ueno, R. Y. Gunji, A. Ohtomo, T. Fukumura and M. Kawasaki, “Effects of thermal annealing of ZnO layers grown by MBE”, J. Crystal Growth, Vol. 214-215, pp. 312-315, 2000.
[2] Q. L. Gu, C. C. Ling, X. D. Chen, C. K. Cheng, A. M. C. Ng, C. D. Beling, S. Fung, A. B. Djurišić, L. W. Lu, G. Brauer and H. C. Ong, “Hydrogen peroxide treatment induced rectifying behavior of Au/n-ZnO contact”, Appl. Phys. Lett., Vol. 90, pp. 122101-1-122101-3, 2007.
[3]A. Nakamura, and J. Temmyo, “Schottky contact on ZnO nano-columnar film with H2O2 treatment”, J. Appl.Phys, Vol. 109, pp. 093517-1-093517-7, 2011.
Chapter4
[1] 林昀、冠昱: 電子學(上), 鼎茂出版社, 2003.
[2] S. R. Meher, K. P. Biju, and M. K. Jain, “Effect of post-annealing on the band gap of sol-gel prepared nano-crystalline MgxZn1-xO(0.0≦x≦0.3) thin films”, J. Sol-Gel Sci. Technol., Vol. 52, pp. 228-234, 2009.