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Theory and simulation of photogeneration and transport in Si-SiOx superlattice absorbers.

Aeberhard U - Nanoscale Res Lett (2011)

Bottom Line: Si-SiOx superlattices are among the candidates that have been proposed as high band gap absorber material in all-Si tandem solar cell devices.As a consequence of the finite number of wells and large built-in fields, the electronic spectrum can deviate considerably from the minibands of a regular superlattice.In this article, a quantum-kinetic theory based on the non-equilibrium Green's function formalism for an effective mass Hamiltonian is used for investigating photogeneration and transport in such devices for arbitrary geometry and operating conditions.

View Article: PubMed Central - HTML - PubMed

Affiliation: IEK-5: Photovoltaik, Forschungszentrum Jülich, D-52425 Jülich, Germany. u.aeberhard@fz-juelich.de.

ABSTRACT
Si-SiOx superlattices are among the candidates that have been proposed as high band gap absorber material in all-Si tandem solar cell devices. Owing to the large potential barriers for photoexited charge carriers, transport in these devices is restricted to quantum-confined superlattice states. As a consequence of the finite number of wells and large built-in fields, the electronic spectrum can deviate considerably from the minibands of a regular superlattice. In this article, a quantum-kinetic theory based on the non-equilibrium Green's function formalism for an effective mass Hamiltonian is used for investigating photogeneration and transport in such devices for arbitrary geometry and operating conditions. By including the coupling of electrons to both photons and phonons, the theory is able to provide a microscopic picture of indirect generation, carrier relaxation, and inter-well transport mechanisms beyond the ballistic regime.

No MeSH data available.


Related in: MedlinePlus

Transverse momentum integrated local density of states of the p-i(SL)-n photodiode at short circuit conditions.
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Figure 3: Transverse momentum integrated local density of states of the p-i(SL)-n photodiode at short circuit conditions.

Mentions: Insertion of the oxide barriers leads to an increase of the effective band gap in the central region of the diode from 1.1 to ~ 1.3 eV, as seen in Figure 3, which shows the transverse momentum-integrated local density of states. In the actual situation of strong band bending, quantization also occurs in the form of notch states in front of the barriers. The density of states at minority carrier contacts is additionally depleted because of the imposition of closed-system boundary conditions that prevent the formation of a dark leakage current under bias.


Theory and simulation of photogeneration and transport in Si-SiOx superlattice absorbers.

Aeberhard U - Nanoscale Res Lett (2011)

Transverse momentum integrated local density of states of the p-i(SL)-n photodiode at short circuit conditions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211303&req=5

Figure 3: Transverse momentum integrated local density of states of the p-i(SL)-n photodiode at short circuit conditions.
Mentions: Insertion of the oxide barriers leads to an increase of the effective band gap in the central region of the diode from 1.1 to ~ 1.3 eV, as seen in Figure 3, which shows the transverse momentum-integrated local density of states. In the actual situation of strong band bending, quantization also occurs in the form of notch states in front of the barriers. The density of states at minority carrier contacts is additionally depleted because of the imposition of closed-system boundary conditions that prevent the formation of a dark leakage current under bias.

Bottom Line: Si-SiOx superlattices are among the candidates that have been proposed as high band gap absorber material in all-Si tandem solar cell devices.As a consequence of the finite number of wells and large built-in fields, the electronic spectrum can deviate considerably from the minibands of a regular superlattice.In this article, a quantum-kinetic theory based on the non-equilibrium Green's function formalism for an effective mass Hamiltonian is used for investigating photogeneration and transport in such devices for arbitrary geometry and operating conditions.

View Article: PubMed Central - HTML - PubMed

Affiliation: IEK-5: Photovoltaik, Forschungszentrum Jülich, D-52425 Jülich, Germany. u.aeberhard@fz-juelich.de.

ABSTRACT
Si-SiOx superlattices are among the candidates that have been proposed as high band gap absorber material in all-Si tandem solar cell devices. Owing to the large potential barriers for photoexited charge carriers, transport in these devices is restricted to quantum-confined superlattice states. As a consequence of the finite number of wells and large built-in fields, the electronic spectrum can deviate considerably from the minibands of a regular superlattice. In this article, a quantum-kinetic theory based on the non-equilibrium Green's function formalism for an effective mass Hamiltonian is used for investigating photogeneration and transport in such devices for arbitrary geometry and operating conditions. By including the coupling of electrons to both photons and phonons, the theory is able to provide a microscopic picture of indirect generation, carrier relaxation, and inter-well transport mechanisms beyond the ballistic regime.

No MeSH data available.


Related in: MedlinePlus