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

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43<br />

In 1988, Girisch et. al. [82] introduced an extended SRH formalism, which<br />

included the effects <strong>of</strong> b<strong>and</strong> bending due to fixed insulator charges <strong>and</strong> charged interface<br />

states.<br />

In Figure 3.3, an illustration <strong>of</strong> the dielectric-semiconductor system under nonequilibrium<br />

conditions is presented. Figure 3.3 shows that, as a result <strong>of</strong> positive fixed<br />

charge (Qt), the energy b<strong>and</strong>s bend down <strong>and</strong> a space charge region is formed.<br />

Figure 3.3 Charge distribution <strong>and</strong> b<strong>and</strong> diagram at the dielectric-semiconductor<br />

interface under non-equilibrium conditions. The non-equilibrίum conditions<br />

are indicated <strong>by</strong> the separation <strong>of</strong> electron <strong>and</strong> hole quasi—Fermi levels Φn <strong>and</strong><br />

. Note that the surface potential ψs is positive when the energy b<strong>and</strong>s bend<br />

down.

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