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6.1 Metastable Effects in µc-Si:H Figure 6.3: (a) ESR spectra of material with three different structure compositions ranging from highly crystalline porous over highly crystalline compact material to material at the threshold between crystalline and amorphous growth, before and after a H 2 O treatment (see section 3.3.1 for details). Panel (b) shows the measured values of the spin densities, (c) the g-value, and (d) the peak to peak line width ∆H pp versus IC RS , before and after treatment. the absolute values of N S , the g-value, and ∆H pp versus IC RS before and after the treatment are shown. As can be seen from the figure, the magnitude of instability effects decreases with increasing amorphous phase content. While for the highest crystallinity (IC RS = 0.82) N S increases by about a factor of three, the changes for the IC RS = 0.71 material are considerably less and almost disappear for the material prepared at the transition between microcrystalline and amorphous growth. The same effect can be observed for the values of g and ∆H pp . Both quantities increase upon treatment, the absolute changes however are less pronounced for the transition material. Because the ESR spectra of µc-Si:H can be described by two contributions at g=2.0043 (db 1 ) and g=2.0052 (db 2 ), it is interesting to see in which way and to what degree the respective spin states are involved in the increase of N S , ∆H pp , and the average g-value. The ESR spectra of Fig. 6.3 (a) therefore have been deconvoluted into these two contributions. The fits were performed using Gaussian lines with a line width of ∆H pp = 5.6 G and ∆H pp = 9.7 G for the db 1 and db 2 67
Chapter 6: Reversible and Irreversible Effects in µc-Si:H Figure 6.4: De-convolution of the ESR spectra already shown in Fig. 6.3 (a) into the two signals at g=2.0043 and 2.0052 before (upper traces) and after the treatment (lower traces). resonance, respectively. For fitting, the line width and the peak position were kept fixed, and only the amplitude of the Gaussian was varied. The results are plotted in Fig. 6.4. In the figure the measured data, the fit curve as well as the individual resonances are shown. The vertical dotted lines indicate the g-values at g=2.0043 and g=2.0052. All spectra show the asymmetric µc-Si:H line shape and can be well approximated by the two resonance lines at g=2.0043 and g=2.0052. Unsurprisingly, for the transition material the relative contribution of both resonances changes only slightly. Before and after the treatment the spectra are dominated by the db 2 signal, which increases slightly after the treatment. Looking at the IC RS = 0.82 material the picture changes considerably. While in the original state the spectrum is dominated by the db 1 signal, the post-treated spectrum is clearly determined by spin centers contributing to the db 2 signal. The same effect, but less pronounced, can be observed for the highly crystalline but compact material. To determine the absolute changes N S was evaluated for each resonance (db 1 and db 2 ) by integrating the individual fit and comparing the contributions to the total intensity of the spectra. The values of N S determined by this procedure are shown in Fig. 6.5. The plot shows the spin density of the individual lines before and after the treatment in H 2 O for each crystallinity investigated. Quite surprisingly, the treatment only effects paramagnetic states resulting in the db 2 resonance, while the line at g=2.0043 remains unaffected. For the I RS C 68 = 0.82 material N S of the
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Forschungszentrum Jülich in der He
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Forschungszentrum Jülich GmbH Inst
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Kurzfassung In der vorliegenden Arb
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Abstract The electronic properties
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Contents 1 Introduction 1 2 Fundame
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CONTENTS C Abbreviations, Physical
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Chapter 1 Introduction Solar cells
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defect states provided that they ar
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Chapter 8: In this chapter, the inf
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Chapter 2 Fundamentals In this firs
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2.2 Electronic Density of States St
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2.2 Electronic Density of States ta
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2.2 Electronic Density of States Fi
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2.3 Charge Carrier Transport influe
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Page 32 and 33: Chapter 3 Sample Preparation and Ch
Page 34 and 35: 3.1 Characterization Methods Figure
Page 36 and 37: 3.1 Characterization Methods Homoge
Page 38 and 39: 3.1 Characterization Methods µ Fig
Page 40 and 41: 3.1 Characterization Methods compar
Page 42 and 43: 3.1 Characterization Methods bution
Page 44 and 45: 3.1 Characterization Methods posite
Page 46 and 47: 3.2 Deposition Technique admixture
Page 48 and 49: 3.3 Sample Preparation 3.3.1 Sample
Page 50 and 51: 3.3 Sample Preparation reverse bias
Page 52 and 53: Chapter 4 Intrinsic Microcrystallin
Page 54 and 55: 4.2 Electrical Conductivity Figure
Page 56 and 57: 4.3 ESR Signals and Paramagnetic St
Page 58 and 59: 4.3 ESR Signals and Paramagnetic St
Page 60 and 61: 4.4 Discussion - Relation between E
Page 62 and 63: 4.4 Discussion - Relation between E
Page 64 and 65: Chapter 5 N-Type Doped µc-Si:H In
Page 66 and 67: 5.2 Electrical Conductivity Figure
Page 68 and 69: 5.4 Dangling Bond Density Figure 5.
Page 70 and 71: 5.5 Conduction Band-Tail States Fig
Page 72 and 73: 5.6 Discussion concentration evalua
Page 74 and 75: 5.7 Summary Figure 5.7: Schematic b
Page 76 and 77: Chapter 6 Reversible and Irreversib
Page 78 and 79: 6.1 Metastable Effects in µc-Si:H
Page 88 and 89: 6.2 Irreversible Oxidation Effects
Page 94 and 95: 6.3 On the Origin of Instability Ef
Page 96 and 97: 6.3 On the Origin of Instability Ef
Page 98 and 99: Chapter 7 Transient Photocurrent Me
Page 100 and 101: 7.2 Transient Photocurrent Measurem
Page 106 and 107: 7.3 Temperature Dependent Drift Mob
Page 108 and 109: 7.4 Multiple Trapping in Exponentia
Page 110 and 111: 7.5 Discussion Table 7.2: Multiple
Page 112 and 113: 7.5 Discussion 7.5.3 The Meaning of
Page 114 and 115: Chapter 8 Schematic Density of Stat
Page 116 and 117: silicon as shown in Fig. 8.1 b, whi
Page 118 and 119: Chapter 9 Summary In the present wo
Page 120 and 121: Appendix A Algebraic Description of
Page 122 and 123: Eq. A.7 then becomes L(t) F = sin(
Page 124 and 125: Appendix B List of Samples Table B.
Page 126 and 127: Table B.3: Parameters of n-type µc
Page 128 and 129: Appendix C Abbreviations, Physical
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µ d Drift mobility µ d,h Hole dri
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Bibliography [1] E. Becquerel. Mém
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BIBLIOGRAPHY [21] D. Will, C. Lerne
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BIBLIOGRAPHY [45] H. Overhof and M.
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BIBLIOGRAPHY [66] P.W. Anderson. Ab
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BIBLIOGRAPHY [93] J.W. Orton and M.
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BIBLIOGRAPHY [121] J.R. Haynes and
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BIBLIOGRAPHY [148] W. Luft and Y.S.
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BIBLIOGRAPHY [170] G.N. Advani, R.
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List of Publications 1. T. Dylla, R
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Acknowledgments At this point, I wa
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Schriften des Forschungszentrums J
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Forschungszentrum Jülich in der He
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