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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

Local density of states in the quantum well region at zero transverse momentum (k∥= 0).
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Figure 4: Local density of states in the quantum well region at zero transverse momentum (k∥= 0).

Mentions: The density of states component at zero transverse momentum displayed in Figure 4 allows the identification of the confined states in the different quantum wells, which are considerably localized because of the large internal field, however, with finite overlap between neighboring wells in the case of the higher states. The ground state is split because of the different effective masses of the charge carriers, the effect being more pronounced for the electrons.


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

Aeberhard U - Nanoscale Res Lett (2011)

Local density of states in the quantum well region at zero transverse momentum (k∥= 0).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Local density of states in the quantum well region at zero transverse momentum (k∥= 0).
Mentions: The density of states component at zero transverse momentum displayed in Figure 4 allows the identification of the confined states in the different quantum wells, which are considerably localized because of the large internal field, however, with finite overlap between neighboring wells in the case of the higher states. The ground state is split because of the different effective masses of the charge carriers, the effect being more pronounced for the electrons.

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