本研究使用金屬鉿（Hf）與金屬鈮（Nb）蒸鍍源，利用電子束蒸鍍在氧氣氛下蒸鍍HfOx、NbOx與HfNbxOy介電薄膜於矽晶片之上並在氮氣氛下以快速退火（500°C~800°C）對介電薄膜作熱處理。隨後以金屬鋁以及氮化鉿作為閘極電極，形成金屬/介電層/半導體（MOS）電容結構，探討不同成份比與熱處理溫度的介電薄膜的電性行為，以及MOS電容器經過氮氫混合氣體退火後的電性穩定度。
本實驗利用X光光電子能量分析儀對薄膜進行化學鍵結型態分析，並對薄膜進行定量分析；以高解析穿透式電子顯微鏡，觀察薄膜截面影像，判斷薄膜及中介層厚度；利用低掠角X光繞射儀對薄膜結晶性進行分析；以橢圓偏光儀模擬薄膜孔隙率；在電性方面以電感電容電阻計量儀量測MOS結構電容器C-V曲線，以直流電壓源/微微安培計量儀量測其漏電流。
實驗結果顯示，藉由調整電子束的功率，可調製不同比例的HfNbxOy複合氧化物介電薄膜，經定量分析發現，初鍍薄膜中，有氧空缺存在，而呈現非計量比。HfNbxOy複合氧化物介電薄膜與矽基材之間有較薄的中介層，最薄可小於1 nm。初鍍HfOx、NbOx與HfNbxOy薄膜為非晶態， 而經快速退火後，呈現結晶型態，並且中介層明顯增厚。而在複合氧化物介電薄膜中，少量的鈮（< 5%）可提高薄膜結晶溫度至600°C，並且中介層的增厚程度也較低。
與HfOx介電薄膜相較，HfNbxOy介電薄膜存在較少的氧化層捕獲電荷，卻有較大的漏電流密度。經過快速退火後的介電薄膜，其漏電流可降低，但氧化層捕獲電荷密度卻上升。在電極材料方面，使用氮化鉿電極可獲得較鋁電極為低的漏電流密度，而MOS電容器經由氮氫混合氣體退火後，可減少介電層捕獲電荷，且電容值與漏電流密度無太大改變，顯示氮化鉿電極在此MOS電容器結構中，有良好的熱穩定性。

Hafnium oxide (HfOx), niobium oxide (NbOx) and hafnium-niobium oxide (HfNbxOy) gate dielectrics were prepared on Si wafers by electron-beam evaporation from Hf and Nb sources, followed by rapid thermal annealing in N2 ambient at 500°C~800°C for 20s. Aluminum (Al) or hafnium nitride (HfN) gate electrodes were deposited on the dielectrics subsequently to form the metal-oxide-semiconductor (MOS) capacitors. Electrical properties of the different dielectrics, before and after rapid thermal annealing, are investigated with Al gate electrode. The stability of the MOS capacitors is investigated by annealing the capacitors in forming gas at 500°C with HfN electrode.
The composition of dielectric thin films was defined by X-ray photoelectron spectroscopy (XPS). The thickness of dielectric thin films was determined by high-resolution transmission electron microscopy (HRTEM). The crystal structure of thin films was identified by glacing incident angle x-ray diffraction (GIAXRD). Ellipsometry was used to measure and simulate the percentage of void in the films. For electrical properties, the C-V curves were obtained by LCR meter (HP4284), and picoampere meter/DC voltage source (HP4140B) was used to measure the leakage current.
By tuning the power of electron beam, we are able to fabricate the HfNbxOy composite oxide dielectric films of various compositions. The dielectric films are non-stoichiometric and are deficient in oxygen. HfNbxOy thin films have a thinner interlayer than HfOx and NbOx, the thinnest interlayer is less than 1 nm. The as-evaporated HfOx, NbOx, and HfNbxOy films are amorphous. After rapid thermal annealing at 500°C, the dielectric films become crystallized and the interlayer thickness increases. Low niobium content (<5%) in the HfNbxOy compositite oxide could increase the crystallization temperature to 600°C and the film also shows a less increase of interlayer thickness.
Compared to pure HfOx, the dielectrics containing niobium have less oxide trap charges but show a greater leakage current. On the electrode materials, the MOS capacitor with HfN gate electrode exhibits a smaller leakage current and reduced oxide trap charges, than the capacitor with Al electrode thus shows a good stability during thermal treatment.

1 R. H. Dennard, F. H. Gaensslen, V. L. Rideout, E. Bassous, and A. R. LeBlanc, Design of ion-implanted MOSFET's with very small physical dimensions, IEEE J. Solid-State Circuit 9, 256 (1974).
2 International Technology Roadmap for Semiconductors, (2006 update)
3 Clen D. Wilk Robert M. Wallace, Exploring the limits of gate dielectric scaling, Semicond. int. June, 153 (2001).
4 D. A. Muller, T. Sorsch, S. Moccio, F. H. Baumann, K. Evans-Lutterodt, and G. Timp, The electronic structure at the atomic scale of ultrathin gate oxides, Nature 399, 758 (1999).
5 J. D. Plummer and P. B. Griffin, Material and process limits in silicon VLSI technology, Proc. IEEE 89, 240 (2001).
6 C. P. Liu, Y. Ma, H. Luftman, and S. J. Hillenius, Preventing boron penetration through 25- gate oxides with nitrogen implant in the Si substrates, IEEE Electron Device Lett. 18, 212 (1997).
7 A. Martin, P. O'Sullivan, and A. Mathewson, Dielectric reliability measurement methods: A review, Microelectron. Reliab. 38, 37 (1998).
8 S. H. Lo, D. A. Buchanan, and Y. Taur, Modeling and characterization of quantization, polysilicon depletion, and direct tunneling effects in MOSFETs with ultrathin oxides, IBM J. Res. Dev. 43, 327 (1999).
9 Chen Chien-Hao, Fang Yean-Kuen, Ting Shyh-Fann, Hsieh Wen-Tse, Yang Chih-Wei, Hsu Tzu-Hsuan, Yu Mo-Chiun, Lee Tze-Liang, Chen Shih-Chang, Yu Chen-Hua, and Liang Mong-Song, Downscaling limit of equivalent oxide thickness in formation of ultrathin gate dielectric by thermal-enhanced remote plasma nitridation, IEEE Trans. Electron Devices 49, 840 (2002).
10 International Technology Roadmap for Semiconductors, (2005 edition)
11 H. Harris, K. Choi, N. Mehta, A. Chandolu, N. Biswas, G. Kipshidze, S. Nikishin, S. Gangopadhyay, and H. Temkin, HfO2 gate dielectric with 0.5 nm equivalent oxide thickness, Appl. Phys. Lett. 81, 1065 (2002).
12 M. Houssa, L. Pantisano, L. A. Ragnarsson, R. Degraeve, T. Schram, G. Pourtois, S. De Gendt, G. Groeseneken, and M. M. Heyns, Electrical properties of high-kappa gate dielectrics: Challenges, current issues, and possible solutions, Mater. Sci. Eng. R-Rep. 51, 37 (2006).
13 K. J. Hubbard and D. G. Schlom, Thermodynamic stability of binary oxides in contact with silicon, J. Mater. Res. 11, 2757 (1996).
14 K. Yamamoto, S. Hayashi, M. Kubota, and M. Niwa, Effect of Hf metal predeposition on the properties of sputtered HfO2/Hf stacked gate dielectrics, Appl. Phys. Lett. 81, 2053 (2002).
15 M. A. Quevedo-Lopez, M. El-Bouanani, B. E. Gnade, R. M. Wallace, M. R. Visokay, M. Douglas, M. J. Bevan, and L. Colombo, Interdiffusion studies for HfSixOy and ZrSixOy on Si, J. Appl. Phys. 92, 3540 (2002).
16 Alexander A. Demkov and Alexandra Navrotsky, Materials fundamentals of gate dielectrics. (Springer, Dordrecht, 2005).
17 H. R. Huff and D. C. Gilmer, High dielectric constant materials :VLSI MOSFET applications. (Springer, Berlin, 2005).
18 H. Stegmann and E. Zschech, Compositional analysis of ultrathin silicon oxynitride gate dielectrics by quantitative electron energy loss spectroscopy, Appl. Phys. Lett. 83, 5017 (2003).
19 A. Nakajima, T. Yoshimoto, T. Kidera, and S. Yokoyama, Low-temperature formation of silicon nitride gate dielectrics by atomic-layer deposition, Appl. Phys. Lett. 79, 665 (2001).
20 C. McGuinness, D. F. Fu, J. E. Downes, K. E. Smith, G. Hughes, and J. Roche, Electronic structure of thin film silicon oxynitrides measured using soft x-ray emission and absorption, J. Appl. Phys. 94, 3919 (2003).
21 M. Copel, E. Cartier, E. P. Gusev, S. Guha, N. Bojarczuk, and M. Poppeller, Robustness of ultrathin aluminum oxide dielectrics on Si(001), Appl. Phys. Lett. 78, 2670 (2001).
22 S. Guha, E. Cartier, N. A. Bojarczuk, J. Bruley, L. Gignac, and J. Karasinski, High-quality aluminum oxide gate dielectrics by ultra-high-vacuum reactive atomic-beam deposition, J. Appl. Phys. 90, 512 (2001).
23 Y. Kim, J. Koo, J. W. Han, S. Choi, H. Jeon, and C. G. Park, Characteristics of ZrO2 gate dielectric deposited using Zr t-butoxide and Zr(NEt2)(4) precursors by plasma enhanced atomic layer deposition method, J. Appl. Phys. 92, 5443 (2002).
24 C. M. Perkins, B. B. Triplett, P. C. McIntyre, K. C. Saraswat, S. Haukka, and M. Tuominen, Electrical and materials properties of ZrO2 gate dielectrics grown by atomic layer chemical vapor deposition, Appl. Phys. Lett. 78, 2357 (2001).
25 C. H. Liu and F. C. Chiu, Electrical characterization of ZrO2/Si interface properties in MOSFETs with ZrO2 gate dielectrics, IEEE Electron Device Lett. 28, 62 (2007).
26 V. Ioannou-Sougleridis, G. Vellianitis, and A. Dimoulas, Electrical properties of Y2O3 high-kappa gate dielectric on Si(001): The influence of postmetallization annealing, J. Appl. Phys. 93, 3982 (2003).
27 A. P. Huang and P. K. Chu, Improvement of interfacial and dielectric properties of sputtered Ta2O5 thin films by substrate biasing and the underlying mechanism, J. Appl. Phys. 97, 114106 (2005).
28 C. H. Hsu, M. T. Wang, and J. Y. M. Lee, Electrical characteristics and reliability properties of metal-oxide-semiconductor field-effect transistors with La2O3 gate dielectric, J. Appl. Phys. 100, 074108 (2006).
29 J. C. Wang, Y. P. Hung, C. L. Lee, and T. F. Lei, Improved characteristics of ultrathin CeO2 by using postnitridation annealing, J. Electrochem. Soc. 151, F17 (2004).
30 S. Jeon and H. S. Hwang, Effect of hygroscopic nature on the electrical characteristics of lanthanide oxides (Pr2O3, Sm2O3, Gd2O3, and Dy2O3), J. Appl. Phys. 93, 6393 (2003).
31 S. C. Chang, S. Y. Deng, and J. Y. M. Lee, Electrical characteristics and reliability properties of metal-oxide-semiconductor field-effect transistors with Dy2O3 gate dielectric, Appl. Phys. Lett. 89, 053504 (2006).
32 Z. B. Fang, S. Chen, Y. Y. Zhu, Y. Q. Wu, Y. L. Fan, Y. Y. Wang, and Z. M. Jiang, Structural and electrical characterization of ultrathin Er2O3 films grown on Si(001) by reactive evaporation, Nanotechnology 18, 155205 (2007).
33 T. M. Pan, C. L. Chen, W. W. Yeh, and S. J. Hou, Structural and electrical characteristics of thin erbium oxide gate dielectrics, Appl. Phys. Lett. 89, 222912 (2006).
34 T. M. Pan, J. D. Lee, W. H. Shu, and T. T. Chen, Structural and electrical properties of neodymium oxide high-k gate dielectrics, Appl. Phys. Lett. 89, 232908 (2006).
35 A. Fissel, Z. Elassar, O. Kirfel, E. Bugiel, M. Czernohorsky, and H. J. Osten, Interface formation during molecular beam epitaxial growth of neodymium oxide on silicon, J. Appl. Phys. 99, 074105 (2006).
36 G. Scarel, E. Bonera, C. Wiemer, G. Tallarida, S. Spiga, M. Fanciulli, I. L. Fedushkin, H. Schumann, Y. Lebedinskii, and A. Zenkevich, Atomic-layer deposition of Lu2O3, Appl. Phys. Lett. 85, 630 (2004).
37 X. B. Lu, Z. G. Liu, Y. P. Wang, Y. Yang, X. P. Wang, H. W. Zhou, and B. Y. Nguyen, Structure and dielectric properties of amorphous LaAlO3 and LaAlOxNy films as alternative gate dielectric materials, J. Appl. Phys. 94, 1229 (2003).
38 K. Yamamoto, W. Deweerd, M. Aoulaiche, M. Houssa, S. De Gendt, S. Horii, M. Asai, A. Sano, S. Hayashi, and M. Niwa, Electrical and physical characterization of remote plasma oxidized HfO2 gate dielectrics, IEEE Trans. Electron Devices 53, 1153 (2006).
39 M. J. Cho, H. B. Park, J. Park, C. S. Hwang, J. C. Lee, S. J. Oh, J. Jeong, K. S. Hyun, H. S. Kang, Y. W. Kim, and J. H. Lee, Thermal annealing effects on the structural and electrical properties of HfO2/Al2O3 gate dielectric stacks grown by atomic layer deposition on Si substrates, J. Appl. Phys. 94, 2563 (2003).
40 Y. S. Lin, R. Puthenkovilakam, and J. P. Chang, Dielectric property and thermal stability of HfO2 on silicon, Appl. Phys.Lett. 81, 2041 (2002).
41 N. Miyata, Two-step behavior of initial oxidation at HfO2/Si interface, Appl. Phys. Lett. 89, 102903 (2006).
42 C. H. Lu, Y. S. Lai, and J. S. Chen, Investigation of the Hf-based gate dielectrics deposited by reactive sputtering in oxygen or nitrogen atmosphere, J. Electrochem. Soc. 153, F189 (2006).
43 G. D. Wilk and R. M. Wallace, Electrical properties of hafnium silicate gate dielectrics deposited directly on silicon, Appl. Phys. Lett. 74, 2854 (1999).
44 Z. M. Rittersma, F. Roozeboom, M. A. Verheijen, J. G. M. van Berkum, T. Dao, J. H. M. Snijders, E. Vainonen-Ahlgren, E. Tois, M. Tuominen, and S. Haukka, HfSiO4 dielectric layers deposited by ALD using HfCl4 and NH2(CH2)(3)Si(OC2H5)(3) precursors, J. Electrochem. Soc. 151, C716 (2004).
45 M. R. Visokay, J. J. Chambers, A. L. P. Rotondaro, A. Shanware, and L. Colombo, Application of HfSiON as a gate dielectric material, Appl. Phys. Lett. 80, 3183 (2002).
46 M. Koike, T. Ino, Y. Kamimuta, M. Koyama, Y. Kamata, M. Suzuki, Y. Mitani, and A. Nishiyama, Dielectric properties of noncrystalline HfSiON, Phys. Rev. B 73, 125123 (2006).
47 P. F. Lee, J. Y. Dai, K. H. Wong, H. L. W. Chan, and C. L. Choy, Growth and characterization of Hf-aluminate high-k gate dielectric ultrathin films with equivalent oxide thickness less than 10 angstrom, J. Appl. Phys. 93, 3665 (2003).
48 Y. K. Chiou, C. H. Chang, C. C. Wang, K. Y. Lee, T. B. Wu, R. Kwo, and M. H. Hong, Effect of Al incorporation in the thermal stability of atomic-layer-deposited HfO2 for gate dielectric applications, J. Electrochem. Soc. 154, G99 (2007).
49 D. H. Triyoso, R. I. Hegde, S. Zollner, M. E. Ramon, S. Kalpat, R. Gregory, X. D. Wang, J. Jiang, M. Raymond, R. Rai, D. Werho, D. Roan, B. E. White, and P. J. Tobin, Impact of titanium addition on film characteristics of HfO2 gate dielectrics deposited by atomic layer deposition, J. Appl. Phys. 98, 054104 (2005).
50 M. Li, Z. Zhang, S. A. Campbell, W. L. Gladfelter, M. P. Agustin, D. O. Klenov, and S. Stemmer, Electrical and material characterizations of high-permittivity HfxTi1-xO2 gate insulators, J. Appl. Phys. 98, 054506 (2005).
51 D. H. Triyoso, R. I. Hegde, J. K. Schaeffer, D. Roan, P. J. Tobin, S. B. Samavedam, B. E. White, R. Gregory, and X. D. Wang, Impact of Zr addition on properties of atomic layer deposited HfO2, Appl. Phys. Lett. 88, 222901 (2006).
52 R. I. Hegde, D. H. Triyoso, S. B. Samavedam, and B. E. White, Hafnium zirconate gate dielectric for advanced gate stack applications, J. Appl. Phys. 101, 074113 (2007).
53 X. F. Yu, C. X. Zhu, M. F. Li, A. Chin, A. Y. Du, W. D. Wang, and D. L. Kwong, Electrical characteristics and suppressed boron penetration behavior of thermally stable HfTaO gate dielectrics with polycrystalline-silicon gate, Appl. Phys. Lett. 85, 2893 (2004).
54 K. Kita, K. Kyuno, and A. Toriumi, Permittivity increase of yttrium-doped HfO2 through structural phase transformation, Appl. Phys. Lett. 86, 102906 (2005).
55 J. Y. Dai, P. F. Lee, K. H. Wong, H. L. W. Chan, and C. L. Choy, Epitaxial growth of yttrium-stabilized HfO2 high-k gate dielectric thin films on Si, J. Appl. Phys. 94, 912 (2003).
56 A. Dimoulas, G. Vellianitis, G. Mavrou, G. Apostolopoulos, A. Travlos, C. Wiemer, M. Fanciulli, and Z. M. Rittersma, La2Hf2O7 high-kappa gate dielectric grown directly on Si(001) by molecular-beam epitaxy, Appl. Phys. Lett. 85, 3205 (2004).
57 H. Lee, S. Jeon, and H. Hwang, Electrical characteristics of a Dy-doped HfO2 gate dielectric, Appl. Phys. Lett. 79, 2615 (2001).
58 N. Lu, H. J. Li, J. J. Peterson, and D. L. Kwong, HfTiAlO dielectric as an alternative high-k gate dielectric for the next generation of complementary metal-oxide-semiconductor devices, Appl. Phys. Lett. 90, 082911 (2007).
59 L. Wang, K. Xue, J. B. Xu, A. P. Huang, and P. K. Chu, Control of interfacial silicate between HfO2 and Si by high concentration ozone, Appl. Phys. Lett. 88, 072903 (2006).
60 H. Watanabe, M. Saitoh, N. Ikarashi, and T. Tatsumi, High-quality HfSixOy gate dielectrics fabricated by solid phase interface reaction between physical-vapor-deposited metal-Hf and SiO2 underlayer, Appl. Phys. Lett. 85, 449 (2004).
61 M. H. Cho, Y. S. Roh, C. N. Whang, K. Jeong, H. J. Choi, S. W. Nam, D. H. Ko, J. H. Lee, N. I. Lee, and K. Fujihara, Dielectric characteristics of Al2O3-HfO2 nanolaminates on Si(100), Appl. Phys. Lett. 81, 1071 (2002).
62 A. Pignolet, G. M. Rao, and S. B. Krupanidhi, Rapid Thermal Processed Thin-Films of Niobium Pentoxide (Nb2O5) Deposited by Reactive Magnetron Sputtering, Thin Solid Films 261, 18 (1995).
63 K. Kukli, M. Ritala, and M. Leskela, Properties of atomic layer deposited (Ta1-xNbx)(2)O5 solid solution films and Ta2O5-Nb2O5 nanolaminates, J. Appl. Phys. 86, 5656 (1999).
64 K. Kukli, M. Ritala, M. Leskela, T. Sajavaara, and J. Keinonen, Atomic layer deposition of HfO2 thin films and nanolayered HfO2-Al2O3-Nb2O5 dielectrics, J. Mater. Sci.-Mater. Electron. 14, 361 (2003).
65 Thaddeus B. Massalski, Hiroaki Okamoto, P.R. Subramanian, and Linda Kacprzak., Binary alloy phase diagrams, 2nd ed. (ASM International, Materials Park, Ohio, 1990).
66 K. Kukli, M. Ritala, M. Leskela, and R. Lappalainen, Niobium oxide thin films grown by atomic layer epitaxy, Chemical Vapor Deposition 4, 29 (1998).
67 S. Venkataraj, R. Drese, C. Liesch, O. Kappertz, R. Jayavel, and M. Wuttig, Temperature stability of sputtered niobium-oxide films, J. Appl. Phys. 91, 4863 (2002).
68 A. Prince P. Villars, and H. Okamoto., Handbook of ternary alloy phase diagrams. (ASM International, Materials Park, OH, 1995).
69 B. E. Deal, Standardized terminology for oxide charges associated with thermally oxidized silicon, IEEE Trans. Electron Devices 27, 606 (1980).
70 James D. Plummer, Michael Deal, and Peter B. Griffin, Silicon VLSI technology :fundamentals, practice and modeling. (Prentice Hall, New Jersey, 2000).
71 Dieter K. Schroder., Semiconductor material and device characterization, Third ed. (Wiley, New Jersey, 2006).
72 E.H. Nicollian and J.R. Brews., MOS (metal oxide semiconductor) physics and technology, Wiley classics library ed. (Wiley, New Jersey, 2003).
73 L. M. Terman, An investigation of surface states at a silicon/silicon oxide interface employing metal-oxide-silicon diodes, Solid-State Electronics 5, 285 (1962).
74 John F. Moulder, William F Stickle, Peter E. Sobol, and Kermeth D. Bomben, Handbook of x-ray photoelectron spectroscopy :a reference book of standard spectra for identification and interpretation of XPS data. (Physical Electronics, Minnesota, 1995).
75 R. W. M. Kwok, XPSPEAK 4.0, Department of chemistry, The chinese University of Hong Kong
76 M. Repoux, COMPARISON OF BACKGROUND REMOVAL METHODS FOR XPS, Surf. Interface Anal. 18, 567 (1992).
77 A. Deshpande, R. Inman, G. Jursich, and C. G. Takoudis, Annealing behavior of atomic layer deposited hafnium oxide on silicon: Changes at the interface, J. Appl. Phys. 99 (2006).
78 V. V. Atuchin, I. E. Kalabin, V. G. Kesler, and N. V. Pervukhina, Nb 3d and O 1s core levels and chemical bonding in niobates, J. Electron Spectrosc. Relat. Phenom. 142, 129 (2005).
79 G. E. McGuire, G. K. Schweitzer, and Thomas A. Carlson, Core electron binding energies in some Group IIIA, VB, and VIB compounds, Inorg. Chem. 12, 2450 (1973).
80 S. K. Dey, A. Das, M. Tsai, D. Gu, M. Floyd, R. W. Carpenter, H. De Waard, C. Werkhoven, and S. Marcus, Relationships among equivalent oxide thickness, nanochemistry, and nanostructure in atomic layer chemical-vapor-deposited Hf-O films on Si, J. Appl. Phys. 95, 5042 (2004).
81 B. Johs, C. Herzinger, B. Guenther, WVASE32 Version 3.460, J. A. Woollam Co., Lincoln, Ne USA
82 S.M. Sze., Physics of semiconductor devices, second ed. (Wiley, New Jersey, 1981).
83 G. D. Wilk, R. M. Wallace, and J. M. Anthony, High-kappa gate dielectrics: Current status and materials properties considerations, J. Appl. Phys. 89, 5243 (2001).
84 J. L. Gavartin, D. M. Ramo, A. L. Shluger, G. Bersuker, and B. H. Lee, Negative oxygen vacancies in HfO2 as charge traps in high-k stacks, Appl. Phys. Lett. 89, 082908 (2006).
85 Y. P. Feng, A. T. L. Lim, and M. F. Li, Negative-U property of oxygen vacancy in cubic HfO2, Appl. Phys. Lett. 87, 062105 (2005).
86 J. Robertson, High dielectric constant gate oxides for metal oxide Si transistors, Rep. Prog. Phys. 69, 327 (2006).
87 M. Houssa, V. V. Afanas'ev, A. Stesmans, and M. M. Heyns, Variation in the fixed charge density of SiOx/ZrO2 gate dielectric stacks during postdeposition oxidation, Appl. Phys. Lett. 77, 1885 (2000).
88 I. Barin, Thermochemical Data of Pure Substances, 3rd ed. (VCH, New York, 1995).
89 N. Novkovski, Conduction and charge analysis of metal (Al, W and Au)-Ta2O5/SiO2-Si structures, Semicond. Sci. Technol. 21, 945 (2006).
90 R. M. Fleming, D. V. Lang, C. D. W. Jones, M. L. Steigerwald, D. W. Murphy, G. B. Alers, Y. H. Wong, R. B. van Dover, J. R. Kwo, and A. M. Sergent, Defect dominated charge transport in amorphous Ta2O5 thin films, J. Appl. Phys. 88, 850 (2000).