Surface and bulk passivation of multicrystalline silicon solar cells by ...
Surface and bulk passivation of multicrystalline silicon solar cells by ... Surface and bulk passivation of multicrystalline silicon solar cells by ...
83 distribution of local currents and voltages for any given terminal voltage. In this model for defect clusters, there are basically two kinds of diodes—a defect-free diode and a diode with defects. Figure 5.4 (a) Α schematic of a defect cluster, and (b) a network model of a solar cell showing voltage and current sources corresponding to dark (indicated by subscript d) and illuminated (indicated by subscript L) conditions, and the resistive components due to the sheet rho of the junction [112]. The characteristics of each cell can be expressed in terms of the Jph and two exponential components of the dark current in a standard form as:
84 Jdark(V) = J01i.exp{(-eV/kT) - 1 } + J02i{exp (-eV/2kT)-1 } The saturation currents J01 and J02 can be written in standard forms for a Ρ/N junction. The total current, J, is given by: J = Jphi - Jdarki(V) where Jphi and Jdarki (V) are the photogenerated and the dark-current densities, respectively, and i corresponds to either a defect-free cell element or a cell element with defects [115, 116]. The values of Jphi, J0ii, and J02i can be estimated from experimental measurements. For example, we select one cell and make an estimate of J ph values for defect-free cells and cells with defects based on LBIC (long wavelength) responses and cell I- V plots. However, J01 and Joe cannot be determined from the cell itself. A library of J01 and J02 values for a variety of materials and for different defect densities is available. It uses a diode array technique that has been described in the literature [117]. Edgepassivated, mesa diode arrays are fabricated on wafers and their electrical characteristics are probed. The device characteristics and their defect data are compiled and used as input in the model. The output of the model generates terminal I- V characteristics of the total cell and spatial distribution of cell voltages and currents for any terminal voltage. These sets of data result in excellent agreement between calculated and actual terminal characteristics of the large-area cell (as seen in next section). It should be pointed out that the network model assumes no internal carrier transport—the communication between the devices occurs via a highly conducting emitter region and the bus bar. 5.4.2 Experimental Approach The major objective of the experimental work is to fabricate solar cells on wafers of known distribution of defect clusters and compare the cell characteristics with theoretical
- Page 51 and 52: 32 atoms, the interface states are
- Page 53 and 54: 34 2.5 Bulk Passivation of Si by Si
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- 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 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.
83<br />
distribution <strong>of</strong> local currents <strong>and</strong> voltages for any given terminal voltage. In this model<br />
for defect clusters, there are basically two kinds <strong>of</strong> diodes—a defect-free diode <strong>and</strong> a diode<br />
with defects.<br />
Figure 5.4 (a) Α schematic <strong>of</strong> a defect cluster, <strong>and</strong> (b) a network model <strong>of</strong> a <strong>solar</strong> cell<br />
showing voltage <strong>and</strong> current sources corresponding to dark (indicated <strong>by</strong><br />
subscript d) <strong>and</strong> illuminated (indicated <strong>by</strong> subscript L) conditions, <strong>and</strong> the<br />
resistive components due to the sheet rho <strong>of</strong> the junction [112].<br />
The characteristics <strong>of</strong> each cell can be expressed in terms <strong>of</strong> the Jph <strong>and</strong> two<br />
exponential components <strong>of</strong> the dark current in a st<strong>and</strong>ard form as:
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