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118 Discussion This means that the number of grains is determined by the ratio of the two fluxes. At the beginning of the process the flux across the interface J1 is larger than the flux to the growing grains J2 (J1 > NGJ2) and the silicon concentration within the aluminum layer still increases. After reaching the point were both fluxes are equal the diffusion towards the grains is larger than the flux across the interface J1 < NGJ2 which leads to a lower concentration of silicon in the aluminum layer. Applying these considerations to the experiments described above the influence of the different parameters on the different process steps has to be taken into account. With increasing annealing temperature TA both J1 and J2 increase (eq. 5.21). An increase of J1 leads to a decrease of the nucleation time tN (eq. 5.17). An increase of J2 leads to an increase of the grain growth velocity vG,0 (eq. 5.18). The nucleation density NG remains approximately constant (eq. 5.20).: J1 J2 TA ↑: (5.21) J1 ↑ ⇒ tN ↓ J2 ↑ ⇒ vG,0 ↑ ≈ const. ⇒ NG ≈ const. Both fluxes J1 and J2 are thermally activated processes. This means that the nucleation density NG is only affected by the difference in thermal activation energy of both processes (Fig. 5.8). The oxide layer thickness will change the diffusion across the interface but will have little effect on the diffusion within the aluminum layer. This means that tN will increase with increasing oxide thickness (eq. 5.17) and vG,0 will be little affected (eq. 5.18). The ratio of both processes is strongly changed by the oxide layer thickness. This means that the nucleation density NG decreases with increasing oxide layer thickness (eq. 5.20). This has been experimentally observed in Fig. 5.9:
5.4 Comparison of the qualitative model with experimental results 119 dOx ↑: (5.22) J1 ↓ ⇒ tN ↑ J2 ≈ const. ⇒ vG ≈ const. J1 J2 ↓ ⇒ N ↓ This basic model is very restricted, because all parameters influence each other. All process steps are linked by the silicon concentration within the aluminum layer. With increasing silicon concentration within the aluminum layer the silicon diffusion into the aluminum will decrease and the grain growth velocity and nucleation rate will increase . However, the simple picture presented here allows a qualitative interpretation of the role of the various parameters in the ALILE process.
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Nucleation and growth during the fo
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"Our ignorance is not so vast as ou
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Zusammenfassung Dünne Schichten au
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• Temperatureprofile mit hoher En
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3.2 In-situ optical microscopy . .
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1 Introduction ’Solar power is ho
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por deposition (PECVD) achieved par
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phous silicon interface layer is ex
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2 State of the art This chapter giv
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2.1 Kinetics of phase change 9 Figu
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2.1 Kinetics of phase change 11 [e
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2.2 Solid Phase Crystallization (SP
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2.2 Solid Phase Crystallization (SP
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2.3 Metal-Induced Crystallization (
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2.4 Aluminum-Induced Layer Exchange
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2.5 Current research involving ALIL
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3 Experimental This thesis is focus
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3.1 Sample preparation 39 does not
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3.1 Sample preparation 41 � �
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3.2 In-situ optical microscopy 43 m
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3.2 In-situ optical microscopy 45 B
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3.3 Electron Back Scatter Diffracti
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4 Results In order to understand an
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4.1 Interlayer 51 (a) (b) Figure 4.
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4.1 Interlayer 53 Figure 4.2: TEM c
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4.1 Interlayer 55 c o u n ts [a .u
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4.1 Interlayer 57 R C [% ] 1 0 0 8
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4.1 Interlayer 59 � � ��
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4.1 Interlayer 61 � � ��
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4.1 Interlayer 63 -2 ] N G [m m 8 6
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4.1 Interlayer 65 TA = 450 °C TA =
Page 83 and 84: 4.1 Interlayer 67 (111) (100) (110)
Page 85 and 86: 4.1 Interlayer 69 4.1.2 Molybdenum
Page 87 and 88: 4.1 Interlayer 71 Fig. 4.17 optical
Page 89 and 90: 4.1 Interlayer 73 R C [% ] 1 0 0 8
Page 91 and 92: 4.2 Temperature profiles 75 face la
Page 93 and 94: 4.2 Temperature profiles 77 � �
Page 95 and 96: 4.2 Temperature profiles 79 R C [%
Page 97 and 98: 4.2 Temperature profiles 81 a small
Page 99 and 100: 4.2 Temperature profiles 83 � �
Page 101 and 102: 4.2 Temperature profiles 85 (a) (b)
Page 107 and 108: 4.2 Temperature profiles 91 ��
Page 109 and 110: 4.2 Temperature profiles 93 in. Thu
Page 111 and 112: 4.2 Temperature profiles 95 ��
Page 113 and 114: 5 Discussion Two of the most import
Page 115 and 116: 5.1 Definition of three crucial Si
Page 125 and 126: 5.2 The ALILE process in the phase
Page 127 and 128: 5.2 The ALILE process in the phase
Page 129 and 130: 5.3 Depletion regions in the ALILE
Page 131 and 132: 5.4 Comparison of the qualitative m
Page 133: 5.4 Comparison of the qualitative m
Page 137 and 138: 5.5 Preferential orientation model
Page 145 and 146: 6 Conclusions In the aluminum-induc
Page 147 and 148: A Preferential orientation calculat
Page 149 and 150: The area of the base of the pyramid
Page 151 and 152: B Abbreviations, symbols and units
Page 153 and 154: symbol unit meaning ∆G a eV activ
Page 155 and 156: Bibliography [1] M. Rogol, S. Doi,
Page 157 and 158: [20] R.W. Bower, R. Baron, J.W. May
Page 159 and 160: [38] J. Jang, J.Y. Oh, S.K. Kim, Y.
Page 161 and 162: [58] N.-P. Harder, T. Puzzer, P. Wi
Page 163 and 164: [72] G. Ekanayake, S. Summers, and
Page 165 and 166: [87] H.R. Philipp and E.A. Taft. An
Page 167 and 168: list of publications journal papers
Page 169 and 170: B. Rau, J. Klein, J. Schneider, E.
Page 171: (2002), 87. S. Gall, M. Muske, I. S
Page 174 and 175: tion. Special thank’s go to Dr. M
Page 176: 10/95-09/98 student electrical engi
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