Surface and bulk passivation of multicrystalline silicon solar cells by ...

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TABLE OF CONTENTS Chapter Page 1 INTRODUCTION 1 1.1 Solar Cell-A Perspective ...... ......... . .. . .......... 1 1.2 How Does A Solar Cell Work, 4 1.3 Silicon Solar Cells 9 1.3.1 Three Generations of Solar Cells .... , ... , . , 9 1.3.2 Silicon Solar Cells ... 11 1.4 . Structure of A Crystalline Si Solar Cell 12 1.5 Role of Defects and Passivation in Solar Cells 13 1.6. Impurity Gettering in PV-Si ................ . ..... . ............ .......... . ............... 16 1.7 .Passivation of Residual Impurities and Defects 17 1.8 Dissertation Outline ........................................................................... 18 2 SILICON NITRIDE LAYER FOR SOLAR CELL APPLICATIONS: AN OVERVIEW.....................................,..,.....................................,.,........ 20 2.1 . Antireflection Coating 20 2.2 . Fabrication of Silicon Nitride for Si Solar Cells 25 2.3 SiN-Si Interface Structure 31 2.4 Surface Passivation of Si by. PECVD SiΝx :H Film 32 2.5 Bulk Passivation of Si by PECVD SiΝx :H Film 34 2.5.1 The Mechanism of H Transport 34 2.5.2 Hydrogen Passivation Effect 35 viii
TABLE OF CONTENTS (Continued) Chapter Page 3 MODELING OF SURFACE RECOMBINATION VELOCITY — ROLE OF THE DAMAGED LAYER 38 3.1 Background 38 3.1.1 Recombination Mechanisms in Silicon 38 3.1.2 Surface Recombination 40 3.2 Modeling of Surface Recombination Velocity at SiN X Si Interface 47 3.2.1 A Program for SRV Calculation 48 3.2.2 Modeling Results and Discussion 51 3.2.3 A Modified Model including Recombination in The Damaged Region 57 3.3 H Transportation Mediated by SiΝx :H Layer .. 61 4 MINORITY-CARRIER LIFETIME MEASUREMENTS 65 4.1 Quasi-Steady-State Photoconductance Decay .... 65 4.2 Wafer Preparation and Passivation Procedure for Reproducible Minority Carrier Lifetime Measurements 67 4.2.1 Objective 67 4.2.2 Influences of Wafer Cleaning 68 4.2.3 Influences of Illumination 71 4.2.4 Discussion 73 5 EFFICIENCY LIMITATIONS CAUSED BY DEFECT CLUSTERS 76 5.1 Background 76 5.2 Objective 77 ix
Page 1 and 2: Copyright Warning & Restrictions Th
Page 3 and 4: ABSTRACT SURFACE AND BULK PASSIVATI
Page 5 and 6: SURFACE AND BULK PASSIVATION OF MUL
Page 7 and 8: APPROVAL PAGE SURFACE AND BULK PASS
Page 9 and 10: Chuan Li, B.L. Sopori, P. Rupnowski
Page 11: ACKNOWLEDGEMENT The work presented
Page 15 and 16: LIST OF TABLES Table Page 2.1 Posit
Page 17 and 18: LIST OF FIGURES (Continued) Figure
Page 19 and 20: LIST OF FIGURES (Continued) Figure
Page 21 and 22: 2 percent; however, soon, more adva
Page 23 and 24: 4 Figure 1.1 World solar module pro
Page 25 and 26: 6 bond is called a hole. It too can
Page 27 and 28: 8 Figure 1.4 The I-V characteristic
Page 29 and 30: 10 First generation cells consist o
Page 31 and 32: 12 Basically, materials for manufac
Page 33 and 34: 14 Defects are generally categorize
Page 35 and 36: 16 copper, or nickel in concentrati
Page 37 and 38: 18 the SiNx:H layer during the ther
Page 39 and 40: CHAPTER 2 SILICON NITRIDE LAYER FOR
Page 41 and 42: 22 reflectance of polished Si can b
Page 43 and 44: 24 information is application-orien
Page 45 and 46: 26 film fed growth (EFG) ribbon sil
Page 47 and 48: 28 Figure 2.5 Deposition of SiΝ :
Page 49 and 50: 30 Figure 2.6 shows the dependence
Page 51 and 52: 32 atoms, the interface states are
Page 53 and 54: 34 2.5 Bulk Passivation of Si by Si
Page 55 and 56: 36 It was found that the bulk lifet
Page 57 and 58: CHAPTER 3 MODELING OF SURFACE RECOM
Page 59 and 60: 40 Figure 3.2 Schematic diagram of
Page 61 and 62: 42 σ and σp are the capture cross
Page 63 and 64:
44 Qsi — charge density induced i
Page 66 and 67:
47 Figure 3.5 The calculated depend
Page 68 and 69:
49 * 10 Λ m; m is in a range from
Page 70 and 71:
51 Na, sigma_n, sigma_p: enter x.xx
Page 72 and 73:
53 Figure 3.7 Measured Seff(Δn) de
Page 74 and 75:
55 curves converge to a single valu
Page 76 and 77:
57 seen that, initially Ss decrease
Page 78 and 79:
59 carrier recombination within the
Page 80 and 81:
61 recombination in the SCR influen
Page 82 and 83:
63 Figure 3.13 shows that: 1) after
Page 84 and 85:
CHAPTER 4 MINORITY-CARRIER LIFETIME
Page 86 and 87:
67 Figure 4.1 Α photograph of QSSP
Page 88 and 89:
69 work. The most convenient is 1 m
Page 90 and 91:
7Ι dependence of the minority carr
Page 92 and 93:
73 It was tempting to assume that l
Page 94 and 95:
75 resistivities and lifetime) do n
Page 96 and 97:
77 5.2 Objective An electronic mode
Page 98 and 99:
79 Figure 5.2 is a photograph of a
Page 100 and 101:
81 impurity-gettering methods which
Page 102 and 103:
83 distribution of local currents a
Page 104 and 105:
85 modeling. Wafers were selected f
Page 106 and 107:
87 Figure 5.5 A comparison of (a) d
Page 108 and 109:
89 alloying results in metallizatio
Page 110 and 111:
91 (i) Defect clusters are the prim
Page 112 and 113:
93 SiNX induced charge density on t
Page 114 and 115:
APPENDIX I PROGRAMS TO CALCULATE SR
Page 116 and 117:
97 phin = -ΕΙ - 1 / beta * log(nd
Page 118 and 119:
99 ίter3 = 0 for xi=1 to nmax/2-1
Page 120 and 121:
101 input "output file name {XXXXXX
Page 122 and 123:
103 F (i) = (exp (beta * (phip - ph
Page 124 and 125:
APPENDIX III COMPUTATIONAL METHOD F
Page 126 and 127:
107 where, dscr is the width of the
Page 128 and 129:
REFERENCES 1. E. Becquerel , C. R.
Page 130 and 131:
44. L.L. Alt, S.W. Ing. Jr. and K.W
Page 132 and 133:
90. B.L. Sopori, Y. Zhang, and N.M.
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