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

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87 Figure 5.5 A comparison of (a) defect-cluster distribution in a wafer and (b) longwavelength LBIC image of the solar cell on a sister wafer. 5.4.3 Results The typical experimental results of material and cell parameters are summarized in Table 5.1 for six cells and their corresponding sister wafers. Column 4 in Table 5.1 shows cell parameters, open-circuit voltage (ν 0 ), short-circuit current (J sc) and external fill factor (FF) of solar cells fabricated using commercial processing. The calculated cell parameters of these cells are shown in column 5. These calculations were performed using actual defect distributions and the following values of the network parameters: Jph(undefected) = 34.00 mA cm-2, Jph(defected) = 23.8 mA cm-2 J0 (undefected) = 3.6x 10 -9 A cm 2, J01 (defected) = 3.6x 10 -8 A cm-2 J02(undefected) = 4.5x10 13 A cm -2, J01 (defected) = 4.5x10 11 A cm2
88 Table 5.1 A Summary of Measured and Calculated Results for Two Typical Solar Cells of Three Groups Cell 9 = Nil (χ 10 cm 2 ) 0.63/09δ 11m ^leasured (VOC JSC FF,Eff) (111V. mA cm-2,%) Calculated (ΥOC JSC internal FF, Eff).(Ad) (mV, mA cm-2, %) : Ι 107 0.75 21.04Ι17.4 604.7, 30.3, 70.05. 601.30.517,78.72,14.437, (0,C7) 3 12.8 Ι 05 1.277 20.86/18.4 604.7. 3Π.13. 69.07. 606.30.65.78.23. 1λ.528, (0,07) 2 12.6 102 1.Ω2 22.72/23.1 59ύ.5. 27.8. 73. 12.8 598. 30.505. 79.04, 14.418, (0.1) 6 103 Π.98 22.73/23.0 545.λ, 27.4. 70.17. 594,30.505.79Α4, 14.418, (0.1) 7 11.2 112 0.638 21.85Ι16.3 581.2, 23,85. 72.8. 5δ0,29.8 .78.33. 13.570. (Π,15) 1ύ.1 113 0.725 23.45/17.θ 580.6, 27,8. 69.7, 581,29.87.78.56, 13.633, (Α0.15) 5 11.2 Νο 633, 31.3, 82.5. 16.3 defect Α realistic external FF (of 0.75) for λ defect-free cell with clusters otherwise the same material quality will have efficiency of 15%. It is seen that the calculated values of V oc and J are in close agreement with the measured values. However, it should be pointed out that the calculated value of FF is internal to the cell (i.e., it does not take into account the metallization effects). However, the measured FF is external and includes the effect of metal shadowing as well as the additional series resistance due to metallization. These features are not included in the model at this time. Based on these results, this theory can be used to calculate the performance of defect-free cells (using the same material quality). Figure 5.6 shows the calculated I-V curve for a defect-free device using the same material quality. Again, the calculated FF is an internal value. Using a corrected FF of 0.72, the expected efficiency of the defect-free cell is 16%. It is interesting to note that there is a significant increase in cell voltage and FF for defect-free cell. This indicates that defect clusters have a strong influence in degrading the cell performance by shunting. In practice, the FF of a mc-Si solar cell is strongly controlled by the cell processing, in particular by the metal firing, and is typically lower than that of a single-crystal cell. The major reason for this is that
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Copyright Warning & Restrictions Th
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ABSTRACT SURFACE AND BULK PASSIVATI
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SURFACE AND BULK PASSIVATION OF MUL
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APPROVAL PAGE SURFACE AND BULK PASS
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Chuan Li, B.L. Sopori, P. Rupnowski
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ACKNOWLEDGEMENT The work presented
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TABLE OF CONTENTS (Continued) Chapt
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LIST OF TABLES Table Page 2.1 Posit
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LIST OF FIGURES (Continued) Figure
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LIST OF FIGURES (Continued) Figure
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2 percent; however, soon, more adva
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4 Figure 1.1 World solar module pro
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6 bond is called a hole. It too can
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8 Figure 1.4 The I-V characteristic
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10 First generation cells consist o
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12 Basically, materials for manufac
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14 Defects are generally categorize
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16 copper, or nickel in concentrati
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18 the SiNx:H layer during the ther
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CHAPTER 2 SILICON NITRIDE LAYER FOR
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22 reflectance of polished Si can b
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24 information is application-orien
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26 film fed growth (EFG) ribbon sil
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28 Figure 2.5 Deposition of SiΝ :
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30 Figure 2.6 shows the dependence
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32 atoms, the interface states are
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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 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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