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Study of the vertical transport in p-doped superlattices based on group III-V semiconductors.

Dos Santos OF, Rodrigues SC, Sipahi GM, Scolfaro LM, da Silva EF - Nanoscale Res Lett (2011)

Bottom Line: The calculations are done within a self-consistent approach to the k→⋅p→ theory by means of a full six-band Luttinger-Kohn Hamiltonian, together with the Poisson equation in a plane wave representation, including exchange correlation effects within the local density approximation.It was shown that the particular minibands structure of the p-doped SLs leads to a plateau-like behavior in the conductivity as a function of the donor concentration and/or the Fermi level energy.In addition, it is shown that the Coulomb and exchange-correlation effects play an important role in these systems, since they determine the bending potential.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Física, Universidade Federal Rural de Pernambuco, R, Dom Manoel de Medeiros s/n, 52171-900 Recife, PE, Brazil. srodrigues@df.ufrpe.br.

ABSTRACT
The electrical conductivity σ has been calculated for p-doped GaAs/Al0.3Ga0.7As and cubic GaN/Al0.3Ga0.7N thin superlattices (SLs). The calculations are done within a self-consistent approach to the k→⋅p→ theory by means of a full six-band Luttinger-Kohn Hamiltonian, together with the Poisson equation in a plane wave representation, including exchange correlation effects within the local density approximation. It was also assumed that transport in the SL occurs through extended minibands states for each carrier, and the conductivity is calculated at zero temperature and in low-field ohmic limits by the quasi-chemical Boltzmann kinetic equation. It was shown that the particular minibands structure of the p-doped SLs leads to a plateau-like behavior in the conductivity as a function of the donor concentration and/or the Fermi level energy. In addition, it is shown that the Coulomb and exchange-correlation effects play an important role in these systems, since they determine the bending potential.

No MeSH data available.


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Conductivity behavior for vertical transport in p-type GaAs/Al0.3Ga0.7As SLs with barrier and well widths equal to 2 nm, as a function of (a) the acceptor concentration N2D and (b) the Fermi energy EF.
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Figure 2: Conductivity behavior for vertical transport in p-type GaAs/Al0.3Ga0.7As SLs with barrier and well widths equal to 2 nm, as a function of (a) the acceptor concentration N2D and (b) the Fermi energy EF.

Mentions: Figure 2a shows the conductivity for heavy holes (σ as a function of the two-dimensional acceptor concentration, N2D, for unstrained GaAs/Al0.3Ga0.7As SLs with barrier width, d1 = 2 nm, and well width, d2 = 2 nm). The conductivity increases until N2D = 3 × 1012 cm-2 because of the upward displacement of the Fermi level, which moves until the first miniband is fully occupied. Afterward, one observes a small range of concentrations with a plateau-like behavior for the conductivity; this is a region where there is no contribution from the first miniband or where the second band is partially occupied, but its contribution to the conductivity is very small. In the group-III arsenides, the minigap is shorter due to the lower values of the effective masses. After NA = 4 × 1012 cm-2, the conductivity increases again because of occupation of the second miniband, and this being very significant in this case. Figure 2b indicates the Fermi level behavior as a function of N2D, where the zero of energy is adopted at the top of the Coulomb barrier, as mentioned before. It is observed that the Fermi energy decreases as N2D increases. This happens because of the exchange-correlation effects, which play an important role in these structures. These effects are responsible for changes in the bending of the potential profiles. The bending is repulsive particularly for this case of GaAs/AlGaAs, and so the Coulomb potential stands out in relation to the exchange-correlation potential.


Study of the vertical transport in p-doped superlattices based on group III-V semiconductors.

Dos Santos OF, Rodrigues SC, Sipahi GM, Scolfaro LM, da Silva EF - Nanoscale Res Lett (2011)

Conductivity behavior for vertical transport in p-type GaAs/Al0.3Ga0.7As SLs with barrier and well widths equal to 2 nm, as a function of (a) the acceptor concentration N2D and (b) the Fermi energy EF.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211228&req=5

Figure 2: Conductivity behavior for vertical transport in p-type GaAs/Al0.3Ga0.7As SLs with barrier and well widths equal to 2 nm, as a function of (a) the acceptor concentration N2D and (b) the Fermi energy EF.
Mentions: Figure 2a shows the conductivity for heavy holes (σ as a function of the two-dimensional acceptor concentration, N2D, for unstrained GaAs/Al0.3Ga0.7As SLs with barrier width, d1 = 2 nm, and well width, d2 = 2 nm). The conductivity increases until N2D = 3 × 1012 cm-2 because of the upward displacement of the Fermi level, which moves until the first miniband is fully occupied. Afterward, one observes a small range of concentrations with a plateau-like behavior for the conductivity; this is a region where there is no contribution from the first miniband or where the second band is partially occupied, but its contribution to the conductivity is very small. In the group-III arsenides, the minigap is shorter due to the lower values of the effective masses. After NA = 4 × 1012 cm-2, the conductivity increases again because of occupation of the second miniband, and this being very significant in this case. Figure 2b indicates the Fermi level behavior as a function of N2D, where the zero of energy is adopted at the top of the Coulomb barrier, as mentioned before. It is observed that the Fermi energy decreases as N2D increases. This happens because of the exchange-correlation effects, which play an important role in these structures. These effects are responsible for changes in the bending of the potential profiles. The bending is repulsive particularly for this case of GaAs/AlGaAs, and so the Coulomb potential stands out in relation to the exchange-correlation potential.

Bottom Line: The calculations are done within a self-consistent approach to the k→⋅p→ theory by means of a full six-band Luttinger-Kohn Hamiltonian, together with the Poisson equation in a plane wave representation, including exchange correlation effects within the local density approximation.It was shown that the particular minibands structure of the p-doped SLs leads to a plateau-like behavior in the conductivity as a function of the donor concentration and/or the Fermi level energy.In addition, it is shown that the Coulomb and exchange-correlation effects play an important role in these systems, since they determine the bending potential.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Física, Universidade Federal Rural de Pernambuco, R, Dom Manoel de Medeiros s/n, 52171-900 Recife, PE, Brazil. srodrigues@df.ufrpe.br.

ABSTRACT
The electrical conductivity σ has been calculated for p-doped GaAs/Al0.3Ga0.7As and cubic GaN/Al0.3Ga0.7N thin superlattices (SLs). The calculations are done within a self-consistent approach to the k→⋅p→ theory by means of a full six-band Luttinger-Kohn Hamiltonian, together with the Poisson equation in a plane wave representation, including exchange correlation effects within the local density approximation. It was also assumed that transport in the SL occurs through extended minibands states for each carrier, and the conductivity is calculated at zero temperature and in low-field ohmic limits by the quasi-chemical Boltzmann kinetic equation. It was shown that the particular minibands structure of the p-doped SLs leads to a plateau-like behavior in the conductivity as a function of the donor concentration and/or the Fermi level energy. In addition, it is shown that the Coulomb and exchange-correlation effects play an important role in these systems, since they determine the bending potential.

No MeSH data available.


Related in: MedlinePlus