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

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Figure 2.3 The calculated reflectance spectra of a Si wafer coated with SiN (n=2 and
0=5.0): double-sided polished (solid line) and (100) double-sided textured
(dotted line). Wafer thickness = 350 um [42].
Figure 2.3 shows the reflectance spectra of Si coated with a non-absorbing
(absorption coefficient a=0) dielectric coating of SiNX with a refractive index (n) of 2.
The thickness (t) is 75 nm. Figure 2.3 also shows that the minimum reflectance of the
polished surface occurs at wavelength λ=4xn1xt
, where, n 1 is the refractive index of the
dielectric layer. If n1 = (n0xn2)1/2, the minimum reflectance is reduced to zero (n 0 and n 2
are the refractive indices of the medium in which the cell is embedded and Si,
respectively). Figure 2.3 shows that texturing results in a very broad null condition- a
feature highly desirable for solar applications. Because an AR coating must be designed
to maximize the performance of the cell for the incident spectral range, device
performance optimization requires that the internal response of the solar cell and the
spectrum for which the solar cell is to be operated be known. In most cases, this