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 ...
69 work. The most convenient is 1 mil polyethylene bag. A well cleaned sample is placed in a polyethylene bag and covered on both sides with I-Ε solution (typically the molarity of 0.1). Excess solution from each surface is squeezed out to leave a thin uniform layer of the solution on the surface. In the measurements performed in this study, the molarity of the solution (within a range of 0.01 and 0.1) did not influence the measurements. Figure 4.2 shows a typical measured lifetime using QSSPCD technique with Sinton apparatus, as a function of time (curve A). The wafer was a semiconductor grade, p-type Si, with a resistivity of 12.8 Ω-cm. Figure 4.2 τb of a p-type Si wafer measured by QSSPCD as a function of time. The sample was cleaned by "ICP" and passivated in IE solution. (A) after ICP; (B) dilute HF dip after (A); (C) dilute HF dip after (B); (D) after oxide removal [108].
70 The lifetime values correspond to injection level of 10 16 cm-3 . The wafer was prepared using the above described ICP and the measurements were made every 5 minutes. Following these measurements, the sample was dipped in dilute HF and dried, and measured (curve B). The curve C was obtained after dipping the sample once again following measurement B. These and similar other results indicated that the sample surface was progressively loosing cleanliness resulting in longer time to reach final lifetime. This indicated that the surface was not properly cleaned and that near-surface region influences the passivation characteristics of I-Ε/Si interface [104]. Figure 4.3 Time dependence of τb after including oxidation in the cleaning procedure, for sequential cleaning steps [108]. Figure 4.2 also indicates that the presence of a very thin passivation layer near the surface can have a strong influence on the passivation. In order to confirm this, the wafers were cleaned and a thin layer of native oxide was permitted to grow on the silicon wafer surface. The oxide was then etched off. Curve D, in Figure 4.2, shows the time
- 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 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.
70<br />
The lifetime values correspond to injection level <strong>of</strong> 10 16 cm-3 . The wafer was<br />
prepared using the above described ICP <strong>and</strong> the measurements were made every 5<br />
minutes. Following these measurements, the sample was dipped in dilute HF <strong>and</strong> dried,<br />
<strong>and</strong> measured (curve B). The curve C was obtained after dipping the sample once again<br />
following measurement B.<br />
These <strong>and</strong> similar other results indicated that the sample surface was<br />
progressively loosing cleanliness resulting in longer time to reach final lifetime. This<br />
indicated that the surface was not properly cleaned <strong>and</strong> that near-surface region<br />
influences the <strong>passivation</strong> characteristics <strong>of</strong> I-Ε/Si interface [104].<br />
Figure 4.3 Time dependence <strong>of</strong> τb after including oxidation in the cleaning procedure, for<br />
sequential cleaning steps [108].<br />
Figure 4.2 also indicates that the presence <strong>of</strong> a very thin <strong>passivation</strong> layer near<br />
the surface can have a strong influence on the <strong>passivation</strong>. In order to confirm this, the<br />
wafers were cleaned <strong>and</strong> a thin layer <strong>of</strong> native oxide was permitted to grow on the <strong>silicon</strong><br />
wafer surface. The oxide was then etched <strong>of</strong>f. Curve D, in Figure 4.2, shows the time
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