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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 GaN/Al0.3Ga0.7N 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 3: Conductivity behavior for vertical transport in p-type GaN/Al0.3Ga0.7N 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 3a depicts the conductivity behavior of heavy holes as a function of N2D for unstrained GaN/Al0.3Ga0.7N SLs with barrier width, d1 = 2 nm, and well width d2 = 2 nm. In this case, the conductivity increases until N2D = 2 × 1012 cm-2 and afterward it remains constant, until N2D = 6 × 1012 cm-2. A simple joint analysis of Figure 3a,b can provide the correct understanding of this behavior. At the beginning, the first miniband is only partially occupied; once the band filling increases, i.e., as the Fermi level goes up to the first miniband value, the conductivity increases. When the occupation is complete (N2D = 2 × 1012 cm-2), one reaches a plateau in the conductivity. After the second miniband begins to get filled up, σ is found to increase again. However, it is important to note that, for the nitrides, the Fermi level shows a remarkable increase as N2D increases, a behavior completely different as compared to that of the arsenides. This can be explained in the following way: for thinner layers of nitrides, the exchange-correlation potential effects are stronger than the Coulomb effects, and so the potential profile is attractive, and it is expected that the Fermi level goes toward the top of the valence band, as well as the miniband energies. This has been discussed in our previous study describing a detailed investigation about the exchange-correlation effects in group III-nitrides with short period layers [13].


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 GaN/Al0.3Ga0.7N 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 3: Conductivity behavior for vertical transport in p-type GaN/Al0.3Ga0.7N 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 3a depicts the conductivity behavior of heavy holes as a function of N2D for unstrained GaN/Al0.3Ga0.7N SLs with barrier width, d1 = 2 nm, and well width d2 = 2 nm. In this case, the conductivity increases until N2D = 2 × 1012 cm-2 and afterward it remains constant, until N2D = 6 × 1012 cm-2. A simple joint analysis of Figure 3a,b can provide the correct understanding of this behavior. At the beginning, the first miniband is only partially occupied; once the band filling increases, i.e., as the Fermi level goes up to the first miniband value, the conductivity increases. When the occupation is complete (N2D = 2 × 1012 cm-2), one reaches a plateau in the conductivity. After the second miniband begins to get filled up, σ is found to increase again. However, it is important to note that, for the nitrides, the Fermi level shows a remarkable increase as N2D increases, a behavior completely different as compared to that of the arsenides. This can be explained in the following way: for thinner layers of nitrides, the exchange-correlation potential effects are stronger than the Coulomb effects, and so the potential profile is attractive, and it is expected that the Fermi level goes toward the top of the valence band, as well as the miniband energies. This has been discussed in our previous study describing a detailed investigation about the exchange-correlation effects in group III-nitrides with short period layers [13].

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