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 ...
79 Figure 5.2 is a photograph of a defect-etched, cast me-Si wafer showing dislocation pile-up in a defect cluster, which extends over several grains [112]. Similar clustering is seen in ribbon material. Typically, the fractional area of the wafer covered by defect clusters is about 5% —10% for a high-quality material; lower-quality material may have a higher-percentage area covered by defect clusters. Figure 5.2 Α defect cluster region showing etch pits produced by defect etching [112].
80 Figure 5.3 An XTEM image of a defect cluster showing metallic precipitation [112]. Defect clustering occurs during crystal growth when local thermal stress exceeds yield stress of some preferred grain orientations causing the stress relief through local generation of defect networks. Defect clusters also serve as internal gettering sites for metallic impurities, and often result in impurity precipitation at these sites. Figure 5.3 is a cross-sectional TEM image of such precipitates in a defect cluster region; other researchers have also observed similar precipitates [113]. Precipitation of impurities at defect clusters is of particular concern, because it is now known that precipitated impurities are difficult to getter by the techniques used in the PV industry (viz, P diffusion for junction formation and Al alloying for back-contact formation). Hence, defect clusters have an important bearing on the development of new
- 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 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.
79<br />
Figure 5.2 is a photograph <strong>of</strong> a defect-etched, cast me-Si wafer showing<br />
dislocation pile-up in a defect cluster, which extends over several grains [112]. Similar<br />
clustering is seen in ribbon material. Typically, the fractional area <strong>of</strong> the wafer covered<br />
<strong>by</strong> defect clusters is about 5% —10% for a high-quality material; lower-quality material<br />
may have a higher-percentage area covered <strong>by</strong> defect clusters.<br />
Figure 5.2 Α defect cluster region showing etch pits produced <strong>by</strong> defect etching [112].
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