The Study of Ohmic Contact to GaN and Investigations on Metal-Oxide-Semiconductor Photodetectors
楊國輝、黃俊達
E-mail: [email protected]
ABSTRACT
The main goal of this dissertation is to investigate the techniques of a low-resistance and high-transparency Ti/indium tin oxide and Ti ohmic contacts to n-type GaN by using plasma pre-treatment. Next, we also focused on the study of GaN
metal-insulator-semiconductor photo-detectors (MIS-PDs) with liquid phase deposition oxide (LPD-oxide). We investigated the mechanism of the dark current for n-type GaN MIS. The responsivity of electrical and optical properties were also studied. Final, one- and two-step rapid-thermal-annealing (RTA) annealing in pure O2 and air ambient has been proposed to activate the Mg-doped p-type GaN films.
This dissertation is divided into four parts. It is addressed as follows:
Part 1(Chapter 1 and 2) investigates nonalloyed transparent Ti/indium tin oxide (ITO) and Ti-only contacts on n-type GaN using plasma pre-treatment. It was found that the ITO/Ti/n-GaN and Ti/n-GaN samples show very low specific contact resistances of 3.2x10-6 Ω-cm2 and 8.7x10-7 Ω-cm2, respectively. Plasma treatments were performed by using a sputtering system at a substrate temperature of 25 ℃ in Ar gas and 30 W plasma power. A novel transparent indium tin oxide (ITO) ohmic contact to n-type GaN with a specific contact resistance of 4.2x10-6 has been obtained. The interfacial properties involving with ITO to n-GaN ohmic contact are different from those of previous reported. Conventionally, ITO films were prepared using electron-beam evaporator and a Schottky contact was thereafter obtained with a barrier height of 0.68 eV. However, in our studies we relied on different deposition technique instead by sputtering the ITO films onto n-type GaN using a RF sputtering system and in result I-V curve revealed a linear behavior.
Part 2 (Chapter 3) demonstrated an efficient and low cost approach to deposit silicon dioxide on gallium nitride by using liquid phase deposition(LPD) at low temperature (30~50 ℃). The LPD technique, utilizing supersaturated H2SiF6 as a source liquid and H3BO3 as a deposition rate controller, has been in detail studied in our work. The effects of different concentrations of H2SiF6 (1 and 0.5M) and H3BO3 (0.01 and 0.005 M) on the LPD-SiO2 thickness and leakage current density were also approached. A maximum SiO2 growth rate of 50.5 nm/hr.
Part 3 (Chapter 4) concentrates on nitride-based ultraviolet MIS-PDs with liquid phase deposition oxide. The minimum
interface-trap density, Dit, of a metal-insulator-semiconductor (MIS) capacitor with a structure of Al/20 nm LPD-SiO2/n-GaN was estimated to be 8.4 x 1011 cm-2 V-1. After annealed in vacuum at 800 ℃ for 60 mins, the Dit was reduced to a value of 1.75 x 1010 cm-2 eV-1. The dark current density was as low as 4.41 x 10-6 A/cm2 for an applied field of 4 MV/cm. A maximum responsivity of 0.112 A/W was observed for incident ultraviolet light of 366 nm with an intensity of 4.15 mW/cm2. A large photocurrent to dark-current contrast ratio higher than four orders of magnitude and a maximum responsivity of 0.65 A/W were observed from the fabricated ITO/LPD-SiO2/GaN MIS UV photo-detectors.
Part 4 (Chapter 5) discusses one- and two-step rapid thermal annealing (RTA) for activating Mg-doped P-type GaN films had been performed to compare with conventional furnace annealing (CFA). The two-step annealing process consists of two annealing steps:
the first step is performed at 750 ℃ for 1 minute and the second step is performed at 600 ℃ for 5 minutes in pure O2 or air ambient. Compared to one-step RTA annealing and CFA annealing, the samples with two-step annealing exhibit higher hole concentration and lower resistiviy.
Keywords : GaN、photo-detectors、photo-current
Table of Contents TABLE OF CONTENTS
SIGNATURE PAGE
LETTER OF AUTHORITY．．．．．．．．．．．．．．．．．．．．．．．iii ENGLISH ABSTRACT．．．．．．．．．．．．．．．．．．．．．．．．iv CHINESE ABSTRACT．．．．．．．．．．．．．．．．．．．．．．．．vi
ACKNOWLEDGMENTS．．．．．．．．．．．．．．．．．．．．．．．viii TABLE OF CONTENTS．．．．．．．．．．．．．．．．．．．．．．．ix LIST OF FIGURES．．．．．．．．．．．．．．．．．．．．．．．．．．xi LIST OF TABLES．．．．．．．．．．．．．．．．．．．．．．．．．．xiv
Chapter 1 Nonalloyed Ti/indium tin oxide and Ti ohmic contacts to n-type GaN using plasma pre-treatment．．．．．．．．．
．．．．．．．．．1
1.1 Introduction．．．．．．．．．．．．．．．．．．．．．．． 1 1.2 Experimental Techniques．．．．．．．．．．．．．．．．．． 2 1.3 Results and Discussions．．．．．．．．．．．．．．．．．．．3 Chapter 2 A novel transparent ohmic contacts of indium tin oxide
to n-type GaN．．．．．．．．．．．．．．．．．．．．．．． 11 2.1 Introduction．．．．．．．．．．．．．．．．．．．．．．． 11 2.2 Experimental Techniques．．．．．．．．．．．．．．．．．．12 2.3 Results and Discussions．．．．．．．．．．．．．．．．．．．12
Chapter 3 Extremely low temperature growth of silicon dioxide on gallium nitride by using liquid phase deposition．．．．．．．
．．．．． 21
3.1 Introduction．．．．．．．．．．．．．．．．．．．．．．． 21 3.2 Experimental Techniques．．．．．．．．．．．．．．．．．． 22
3.3 Results and Discussions．．．．．．．．．．．．．．．．．．．23 3.3.1 Dependence of thickness．．．．．．．．．
．．．．．．．23
3.3.2 Leakage current density．．．．．．．．．．．．．．．．24 3.3.3 Investigations of EDX, XPS and Auger depth-profile．．．． 25
Chapter 4 Nitride-Based UV Metal-Insulator-Semiconductor Photo-detector with Liquid-Phase-Deposition Oxide．．．．．．．
．．．．．．．．．38
4.1 Al-gate/SiO2/n-GaN MIS photo-detectors．．．．．．．．．．． 39 4.1.1 Introduction．．．．．．．．．．．．．．．．．．．．． 40 4.1.2 Experimental Techniques．．．．．．．．．．．．．．．．42 4.1.3 Results and discussion．．．．．．．．．．．．．．．．．42 4.2 ITO-gate/SiO2/n-GaN MIS photo-detectors．．．．．．．．．．．43 4.2.1 Introduction．．．．．．．．．．．．．．．．．．．．． 44 4.2.2 Experimental Techniques．．．．．．．．．．．．．．．．45 4.2.3 Results and discussion．．．．．．．．．．．．．．．．．46 Chapter 5 Activation of Mg-doped P-GaN by using two-step annealing．．．58 5.1 Introduction．．．．．．．．．．．．．．．．．．．．．．． 58 5.2 Experimental Techniques．．．．．．．．．．．．．．．．．．59 5.3 Results and Discussions．．．．．．．．．．．．．．．．．．．60 Chapter 6 Conclusions．．．．．．．．．．．．．．．．．．．．．． ． 61 References．．．．．．．．．．．．．．．．．．．．．．．．．．．．． 71 Bibliography．．．．．．．．．．．．．．．．．．．．．．．．．．．． 78
List of Figures
Fig. 1-1 RF sputtering system．．．．．．．．．．．．．．．．．．．．．．6 Fig. 1-2 I-V characteristics of ITO/Ti/n-GaN and Ti/n-GaN samples．．．．．．．7
Fig. 1-3 Surface AES data for sample C and D．．．．．．．．．．．．．．．．8 Fig. 1- 4 Transmittance of the ITO films in our studies．．．．．．．．．．．． 9
Fig. 1-5 A representative cross section of Ti and Ti/ITO ohmic contacts to n-type GaN．．．．．．．．．．．． ．．．．．
．．．．．．． ．．．． 10
Fig. 2-1 I-V curves of ITO/n-GaN devices for sample A, B, and C．．．．．．． 11 Fig. 2-2 Surface AES data for sample D and E．．．．．．．．．．．．．．． 12 Fig. 2-3 Transmittance of sputtered ITO films with non-annealed and 500℃ annealed samples．．．．．．．．．．．．．．．．．．．．．． ．．． 13
Fig. 2-4 A representative ITO/n-type GaN cross section．．．．．．．．．．．．14
Fig. 3-1 The preparation of the saturated solution of LPD-SiO2 and the deposition flowchart．．．．．．．．．．．．．．．．
．．．．．．．． 21
Fig. 3-2 The thickness of LPD-SiO2 as a function of growth temperature for immersion time of 1 hour．．．．．．．．．．．．
．．．．．．．22
Fig. 3-3 The thickness of LPD-SiO2 versus deposition times for different concentrations of H2SiF6 and H3BO3．．．．．．．．
．．．．．．．．23
Fig. 3-4 The annealing effect, 800℃ in N2 ambient for 1 hour, on thickness of LPD-SiO2 films．．．．．．．．．．．．．．．
．．．．．．．．．24
Fig. 3-5 The leakage current density as a function of electric field for different concentrations of H3BO3 (0.01 and 0.005M), but H2SiF6 was kept at
0.5M．．．．．．．．．．．．．．．．．．．．．．．．．．．．25
Fig. 3-6 The leakage current density as a function of electric field for different concentrations of H3BO3 (0.01 and 0.005M), but H2SiF6 was kept at 1M．．．．．．．．．．．．．．．．．．．．．．．．．．．．．26
Fig. 3-7 Annealing effect on leakage current density．．．．．．．．．．．．．27 Fig. 3-8 Element analysis of LPD-SiO2 by using EDX．．．．．．．．．．．．28 Fig. 3-9 Composition analysis of LPD-SiO2 by using XPS．．．．．．．．．． 29
Fig. 3-10 Auger depth-profile for (a) as-grown and (b) annealed LPD-SiO2 films on GaN．．．．．．．．．．．．．．．．．
．．．．．．．．．．．30
Fig. 3-11 The Growth model of LPD-SiO2 on GaN．．．．．．．．．．．．． 31 Fig. 4-1 Device structure of n-type GaN MIS photo-detector．．．．．．．．．．47
Fig. 4-2 LPD-SiO2 thickness vs growth time under different growth temperatures for concentrations of H2SiF6 (0.5 M) and H3BO3 (0.01 M) ．．．．．．．．48
Fig. 4-3 AFM image of 20- nm- thick LPD-SiO2．．．．．．．．．．．．．． 49
Fig. 4-4 Film thickness versus growth time under different concentrations of H3BO3 while H2SiF6 in held constant at 0.5 M for nonannealed and annealed samples．．．．．．．．．．．．．．．．．．．．．．．．．．．50
Fig. 4-5 XPS spectrum of Si 2p core level for LPD-SiO2．．．．．．．．．．．51 Fig. 4-6 Dark I-V characteristic of Al/20nm LPD-SiO2/n-GaN MIS capacitor．． 52
Fig. 4-7 Responsivity vs different reverse bias for MIS PD with 10-nm-thick LPD-SiO2. The inset shows the current densities vs different applied bias for dark and photoilluminated PD．．．．．．．．．．．．．．．．．．53
Fig. 4-8 Band diagram for defect-assisted tunneling. The holes tunnel through donorlike defects in LPD-SiO2 toward the Al gate electrode．．．．．． 54
Fig. 4-9 XPS spectrum of (a) Si2p and (b) O1s for LPD-SiO2 on GaN．．．．．．．55
Fig. 4-10 I-V characteristics of ITO/10-nm LPD-SiO2/GaN MIS and ITO/GaN photodetectors measured in dark and under 366-nm illumination．．．．．．．．．．．．．．．．．．．．．．．．．56
Fig. 4-11 Spectral responsivity of GaN MIS UV photodetectors．57
Fig. 5-1 A representative cross section of Ni and Au ohmic contacts to p-type GaN．64 Fig. 5-2 I-V curves corresponding to different annealing cases．．．．．．．．．65 Fig. 5-3 Resistivity as a function of different annealing cases．．．．．．．．． 66 Fig. 5-4 Concentration of different annealing cases．．．．．．．．．．．．．67 Fig. 5-5 SIMS profiles of hydrogen in as-deposited and case D sample．．．．．．68 Fig. 5-6 PL spectrum for GaN samples annealed in a pure O2 ambient．．．．．．69
List of Tables
Table 2-1 Different treatments of GaN samples and its specific contact resistance．16
Table 5-1 Six sets of different experimental cases for activating Mg-doped p-type GaN film．．．．．．．．．．．．．．．．
．．．．．．．．．．．63 REFERENCES
[1] S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, Jpn. J. Appl. Phys. 34 (1995) L797.
[2] S. Nakamura, T. Mokia, and M. Senoh, Appl. Phys. Lett. 64 (1994) 1689.
[3] S. Nakamura, M. Senoh, S. Nagahama, N. Iwasa, T. Yamada, T. Matsushita, Y. Sugimoto, and H. Kiyodo, Appl. Phys. Lett. 70 (1996) 868.
[4] E. Kaninska, A. Piotrowska, M. Guziewicz, S. Kasjaniuk, A. Bracz, E. Dynowska, M. D. Bremser, O. H. Nam, and R. F. Davis, Mater. Res.
Soc. Symp. Proc. 449 (1997) 1055.
[5] J. D. Guo, C. I. Lin, M. S. Feng, F. M. Pan, G. C. Chi, and C. T. Lee, Appl. Phys. Lett. 68 (1996) 235.
[6] M. E. Lin, Z. Ma, F. Y. Huang, Z. F. Fan, L. H. Allen, and H. Morkoc, Appl. Phys. Lett. 64 (1994) 100.
[7] Zhifang Fan, S. Noor Mohammad, Wook Kim, ?zg?r Aktas, Andrei E. Botchkarev, and Hadis Morkoc, Appl. Phys. Lett. 68 (1996) 1672.
[8] J. K. Sheu, Y. K. Su, G. C. Chi, M. J. Jou, and C. M. Chang, Appl. Phys. Lett. 72 (1998) 3317.
[9] J. K. Sheu, Y. K. Su, G. C. Chi, M. J. Jou, and C. M. Chang, Solid-State Electronics 43 (1999) 2081.
[10] D. W. Jenkins and J. D. Dow, Phys. Rev. B 39 (1989) 3317.
[11] S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, Jpn. J. Appl. Phys., Part 2 34L (1995) 797.
[12] S. J. Chang, W. C. Lai, Y. K. Su, J. F. Chen, C. H. Liu, and U. H. Liaw, IEEE J. Sel. Top. Quan. Electron., 8 (2002) 278.
[13] S. Nakamura, M. Senoh, S. Nagahama, N. Iwasa, T. Yamada, T. Matsushita, Y. Sugimoto, and H. Kiyodo, Appl. Phys. Lett. 70(1996) 868.
[14] J. S. Foresi and T. D. Moustakas, Appl. Phys. Lett. 82 (1993) 2859 .
[15] J. D. Guo, C. I. Lin, M. S. Feng, F. M. Pan, G. C. Chi, and C. T. Lee, Appl. Phys. Lett. 68 (1996) 235.
[16] M. E. Lin, Z. Ma, F. Y. Huang, Z. F. Fan, L. H. Allen, and H. Morkoc, Appl. Phys. Lett. 64 (1994) 1003.
[17] Z. Fan, S. N. Mohammad, W. Kim, ?. Aktas, A. E. Botchkarev, and H. Morkoc, Appl. Phys. Lett. 68 (1996) 1672.
[18] Y. K. Su, S. J. Chang, C. H. Chen, J. F. Chen, G. C. Chi. J. K. Sheu, W. C. Lai, and J. M. Tsai, IEEE Sensors Journal, 2 (2002) 366.
[19] J. K. Sheu, Y. K. Su, G. C. Chi, M. J. Jou, and C. M. Chang, Solid-State Electronics 43 (1999) 2081.
[20] D. W. Kim, Y. J. Sung, J. W. Park, G. Y. Yeom, Thin Solid Films, 87 (2001) 398.
[21] D. W. Jenkins and J. D. Dow, Phys. Rev. B 39 (1989) 3317.
[22] S. J. Fonash, S. Ashok, and R. Singh, Appl. Phys. Lett. 39 (1981) 423.
[23] M. J. Tsai, A. L. Fahrenbruch, and R. H. Bube, J. appl. Phys. 51 (1980) 2696.
[24] S. Nakamura, M. Senoh, N. Iwasa and S. Nagahama: Jpn. J. Appl. Phys. 34 (1995) L797.
[25] S. Nakamura, T. Mukai and M. Senoh: Jpn. J. Appl. Phys. 30 (1991) L1998.
[26] S. J. Chang, W. C. Lai, Y. K. Su, J. F. Chen, C. H. Liu and U. H. Liaw: IEEE J. Sel. Top. Quan. Electron. 8 (2002) 278.
[27] S. Nakamura, M. Senoh, S. Nagahama, N. Iwasa, T. Yamada, T. Matsushita, Y. Sugimoto and H. Kiyodo: Appl. Phys. Lett. 70 (1996) 868.
[28] S. Nakamura, M. Senoh, S. Nagahama, N. Iwasa, T. Yamada, T. Matsushita, H. Kiyoku and Y. Sugimoto: Jpn. J. Appl. Phys. 35 (1996) L74.
[29] C. K. Wang, R. W. Chuang, S. J. Chang, Y. K. Su, S. C. Wei, T. K. Lin, T. K. Ko, Y. Z. Chiou and J. J. Tang: Mater. Sci. & Eng. B 119 (2005) 25.
[30] C. T. Lee, H. W. Chen and H. Y. Lee, Appl. Phys. Lett. 82 (2003) 4304.
[31] T. Rotter, D. Mistele, J. Stemmer, F. Fedler, J. Aderhold, J. Graul, V. Schwegler, C. Kirchner, and M. Kamp and M. Heuken: Appl. Phys.
Lett. 76 (2000) 3923.
[32] H. C. Casey, Jr., G. G. Fountain, R. G. Alley, B. P. Keller and Steven P. DenBaars: Appl. Phys. Lett. 68 (1996) 1850.
[33] Kevin Matocha, Ronald J. Gutmann and T. Paul Chow: IEEE Trans. Electron Devices. 50 (2003) 1200.
[34] S. J. Chang, Y. K. Su, F. S. Juang, C. T. Lin, C. D. Chiang and Y. T. Cherng: IEEE J. Quantum Electron. 36 (2000) 583.
[35] C. T. Lin, Y. K. Su, S. J. Chang, H. T. Huang, S. M. Chang and T. P. Sun: IEEE Photo. Technol. Lett. 9 (1997) 232.
[36] J. D. Hwang, G. H. Yang, W. T. Chang, C. C. Lin, R.W. Chuang and S.J. Chang: Microelectronic Engineering, 77 (2005) 71.
[37] C. J. Huang, Jiann-Ruey Chen and S.P. Huang: Mater. Chem. & Phys. 70 (2001) 78.
[38] J. S. Chou and S. C. Lee: Appl. Phys. Lett. 64 (1994) 1971.
[39] M. P. Houng, C. J. Huang, Y. H. Wang, N. F. Wang and W. J. Chang: J. Appl. Phys. 82 (1997) 5788.
[40] H. R. Wu, K. W. Lee, T. B. Nian, D. W. Chou, J. J. Huang, Y. H. Wang, M. P. Houng, P. W. Sze, Y. K. Su, S. J. Chang, C. H. Ho, C. I.
Chiang, Y. T. Chern, F. S. Juang, T. C. Wen, W. I. Lee and J. I. Chyi: Mater. Chem. & Phys. 80 (2003) 329.
[41] D. W. Chou, K. W. Lee, J. J. Huang, H. R. Wu, Y. H. Wang, M. P. Houng, S. J. Chang and Y. K.Su: Jpn. J. Appl. Phys. 41 (2002) L748.
[42] K. W. Lee, D. W. Chou, H. R. Wu, J. J. Huang, Y. H. Wang, M. P. Houng, S. J. Chang and Y. K. Su: Electron. Lett. 38 (2002) 830.
[43] J. D. Hwang, Z. Y. Lai, C. Y. Wu and S. J. Chang: Jpn. J. Appl. Phys. 44 (2005) 1726.
[44] C. T. Lee, H. Y. Lee and H. W. Chen: IEEE Electron. Dev. Lett. 24 (2003) 54.
[45] X. A. Cao, H. Cho, S. J. Pearton, G. T. Dang, A. P. Zhang, F. Ren, R. J. Shul, L. Zhang, R. Hickman, and J. M. Van Hove: Appl. Phys. Lett.
75 (1998) 232.
[46] D. J. Fu, Y. H. Kwon, T. W. Kang, C. J. Park, K. H. Baek, H. Y. Cho, D. H. Shim, C. H. Lee and K. S. Chung: Appl. Phys. Lett. 80 (2002) 446.
[47] J. I. Pankove: Mater. Res. Soc. Symp. Proc. 162 (1990) 515.
[48] G. Parish, S. Keller, P. Kozodoy, J. A. Ibbetson, H. Marchand, P. T. Fini, S. B. Fleischer, S. P. DenBaars and U. K. Mishra: Appl. Phys. Lett.
75 (1999) 247.
[49] Q. Chen, J. W. Yang, A. Osinsky, S. Gangopadhyay, B. Lim, M. Z. Anwar, M. Asif Khan, D. Kuksenkov and H. Temkin: Appl. Phys. Lett.
70 (1997) 2277.
[50] P. Kung, X. Zhang, D. Walker, A. Saxler, J. Piotrowski, A. Rogalski and M. Razeghi: Appl. Phys. Lett. 67 (1995) 3792.
[51] H. C. Casey, Jr., G. G. Fountain, R. G. Alley, B. P. Keller and S. P. DenBaars: Appl. Phys. Lett. 68 (1996) 1850.
[52] K. Matocha, R. J. Gutmann and T. P. Chow: IEEE Trans. Electron Devices 50 (2003) 1200.
[53] S. J. Chang, Y. K. Su, F. S. Juang, C. T. Lin, C. D. Chiang and Y. T. Cherng: IEEE J. Quantum Electron. 36 (2000) 583.
[54] C. T. Lin, Y. K. Su, S. J. Chang, H. T. Huang, S. M. Chang and T. P. Sun: IEEE Photonics. Technol. Lett. 9 (1997) 232.
[55] J. D. Hwang, G. H. Yang, W. T. Chang, C. C. Lin, R. W. Chuang and S. J. Chang: Microelectron. Eng.77 (2005) 71.
[56] C. J. Huang, J. R. Chen and S. P. Huang: Mater. Chem. Phys. 70 (2001) 78.
[57] H. R. Wu, K. W. Lee, T. B. Nian, D. W. Chou, J. J. Huang, Y. H. Wang, M. P. Houng, P. W. Sze, Y. K. Su, S. J. Chang, C. H. Ho, C. I.
Chiang, Y. T. Chern, F. S. Juang, T. C. Wen, W. I. Lee and J. I. Chyi:Mater. Chem. Phys. 80 (2003) 329.
[58] D. W. Chou, K. W. Lee, J. J. Huang, H. R. Wu, Y. H. Wang, M. P. Houng, S. J. Chang and Y. K. Su: Jn. J. Appl. Phys. 41 (2002) L748.
[59] M. L. Lee, J. K. Sheu, W. C. Lai, S. J. Chang, Y. K. Su, M. G. Chen, C. J. Kao, G. C. Chi and J. M. Tsai: Appl. Phys. Lett. 28 (2003) 2913.
[60] B. C. Hsu, S. T. Chang, T. C. Chen, P. S. Kuo, P. S. Chen, Z. Pei and C. W. Liu: IEEE Electron Device. Lett. 24 (2003) 318.
[61] Y. Z. Chiou, Y. K. Su, S. J. Chang, J. Gong, C. S. Chang, and S. H. Liu: J. Electron. Mater. 32 (2003) 395.
[62] J. D. Hwang, and C. C. Lin: Thin Silid Films, 491 (2005) 276.
[63] J. I. Pankove: Mater. Res. Soc. Symp. Proc. 162 (1990) 515.
[64] S. Arulkumaran, T. Egawa, H. Ishikawa, T. Jimbo, and M. Umeno: Appl. Phys. Lett. 73 (1998) 809.
[65] D. Fu, and T. W. Kang: Jpn. J. Appl. Phys. 41 (2002) L1437.
[66] C. T. Lee, H. Y. Lee, and H. W. Chen: IEEE Electron Device Lett. 24 (2003) 54.
[67] J. S. Chou and S. C. Lee, Appl. Phys. Lett. 64 (1994) 1971.
[68] C. J. Huang, M. P. Houng, Y. H. Wang, H. H. Wang, J. Appl. Phys. 86 (1999) 7151.
[69] J. D. Hwang, Gwo Huei Yang, Yuan Yi Yang and Pin Cuan Yao: Jpn. J. Appl. Phys. 44 (2005) 7913.
[70] S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, Jpn. J. Appl. Phys. Part 2 Letter 34 (1995) L797-800 . [71] S. Nakamura, T. Mokia, and M. Senoh, Appl. Phys. Lett. 64 (1994) 1689.
[72] S. Nakamura, M. Senoh, S. Nagahama, N. Iwasa, T. Yamada, T. Matsushita, Y. Sugimoto, and H. Kiyodo, Appl. Phys. Lett. 70 (1996) 868.
[73] D. W. Jenkins and J. D. Dow, Phys. Rev. B 39 (1989) 3317.
[74] J. I. Pankove: Mater. Res. Soc. Symp. Proc. (1990 )160:515.
[75] S. W. Kim, J. M. Lee, Chul Huh, N. M. Park, H. S. Kim, I. H. Lee, and S. J. Park, Appl. Phy. Lett. 70 (2000) 3079.
[76] S. Nakamura, T. Mukai, M. Senoh, and N. Iwasa, Jpn. J. Appl. Phys. Part 2 Letter 31 (1992) L139-2.
[77] C. H. Kuo, S. J. Chang, Y. K. Su, L. W. Wu, J. K. Sheu, C. H. Chen and G. C. Chi, Jpn. J. Appl. Phys. Part 2 Letter 41 (2002) L112-5.
[78] H.C. Cheng, C.Y. Huang, F.S. Wang, K.H. Lin, F.G. Tarntair; Jpn. J. Appl. Phys. Part 2 Letter 39 (2000) L19-21.
[79] James D. Plummer, Michal D. Deal, Peter B. Griffin, Silicion VLSI technology, Prentice Hall, Inc. U.S.A.
