Monocrystalline semiconductors

Quantum efficiency diffusion length Lq

Подпись: JQ,mono Подпись: L ShLsmh(WhJL)+Dn cosh{WbJL) SbLcosb{WbJL)+Dnsmh(WbJL) Подпись: (C.10)

For planar monocrystalline sheets of Si material, the effective quantum efficiency diffusion length

depends on the diffusion length L of the semiconductor, the back surface recombination velocity Sb, the base thickness Wbas, and the minority carrier diffusion coefficient Dn [24]. The value of LQmono equals the effective current-voltage diffusion length LJ>mono, which determines the dark saturation current density

image529(C. ll)

of a single-sided p-n junction (Eqs. (8) and (9) of Ref. [24]). The symbol q denotes the elementary charge and nQ is the equilibrium minority carrier concentration. The quantum efficiency can therefore be used to evaluate the amount of recombination in the base of a single-crystalline solar cell [24, 177, 411].

Подпись: JC,mono Подпись: L SbL{cosh{WbJL)-)+Dn sinh{WJL) SbL sinh(fFte /L)+Dn cosh(fFte /L) Подпись: (C.12)

Collection diffusion length Lc The collection diffusion length

for monocrystalline cells is closely related to the collection probability for weakly ab­sorbed light (Eq. 6 in Ref. [24]). A thin-film cell with base thickness Wbas, diffusion

length L, SRV Sb, and negligible recombination in the emitter would generate exactly the same short-circuit current under spatially homogeneous carrier generation as a semi­infinitely thick monocrystalline cell with a base diffusion length of Lc>mom•

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