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

More documents

Recommendations

Info

21 Figure 2.1 SEM picture of a typical texturized silicon surface using conventional NaOH texturization bath [39]. Figure 2.2 The calculated reflectance spectra of a bare Si wafer for different surface conditions: (a) polished and (b) (100) textured. Wafer thickness =300 μm [40]. Figure 2.2 summarizes the reflectance spectra of Si for two surface conditions: double-side polished and double-side textured [40], respectively, which shows that the
22 reflectance of polished Si can be greatly lowered by texturing. For a well-textured surface of a (100)-oriented wafer, the reflectance can be as low as 0.1. The other approach is to deposit thin coatings of a material on top of the surface of a photovoltaic cell that reduces the light reflection and increases light transmission. These coatings are called antireflection (AR) coatings. The materials include SiO2, 1'iO2, ΖnO2, MgF and Si3N4. A single layer of the antireflection material is usually several hundred nanometers thick. The most common method for broadbanding in optical applications is to use multilayer coatings that exhibit reflectance nulls at several wavelengths [41]. If the nulls are located close to each other, it can result in a very low reflectance surface. This approach has been successfully applied in other optical devices, such as beam splitters, architectural glass windows, and optical instruments. But, because of cost considerations, a conventional multilayer approach is not suitable for solar cells. However, the broadband anti-reflection features in solar cells are obtained through the use of rough surfaces, in conjunction with a single-layer of AR coating. In the past, the PV industry has used materials, such as SίO2 and TiO2 for AR coatings. SίO2 is not an ideal material for AR coating of Si because its refractive index (n=1.45) is too low. However, it offers the advantage of providing surface passivation. On the other hand, TiO2 is better matched optically with Si, but does not contribute to surface passivation. SIN offers a better match as an AR coating for Si, but the cost of depositing nitride layers is generally high and is not warranted for low-cost solar cells. However, the nitridation process can save other process steps and contribute to significant improvement of the cell efficiency, making it a viable option [42].
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 and 12: ACKNOWLEDGEMENT The work presented
Page 13 and 14: TABLE OF CONTENTS (Continued) Chapt
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: CHAPTER 2 SILICON NITRIDE LAYER FOR
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.
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?