Electronic states in GaAs-AlAs short-period superlattices: energy levels and symmetry

Ge, Weikun; Schmidt, W.; Sturge, M. D.; Pfeiffer, L. N.; West, K. W.

doi:10.1016/0022-2313(94)90039-6

Cited by 33 publications

(2 citation statements)

References 62 publications

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“…A periodic structure is basically the best option that we know to mimic a large solid. The concept of the superlattice has been extended far beyond the originally proposed systems, from the extreme of monolayer superlattices, [10] in terms of the layer thickness to another extreme, the inorganic-organic hybrid superlattices representing a drastically different chemical bonding [11]. The Graphene/Silicon (Gr/Si) superlattice to be explored in this work represents an example of a superlattice structure with uniqueness in both layer thickness and chemical bonding.…”

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confidence: 99%

Binding Graphene Sheets Together Using Silicon: Graphene/Silicon Superlattice

Zhang

Tsu

2010

Nanoscale Res Lett

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We propose a superlattice consisting of graphene and monolayer thick Si sheets and investigate it using a first-principles density functional theory. The Si layer is found to not only strengthen the interlayer binding between the graphene sheets compared to that in graphite, but also inject electrons into graphene, yet without altering the most unique property of graphene: the Dirac fermion-like electronic structure. The superlattice approach represents a new direction for exploring basic science and applications of graphene-based materials.

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confidence: 99%

Binding Graphene Sheets Together Using Silicon: Graphene/Silicon Superlattice

Zhang

Tsu

2010

Nanoscale Res Lett

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“…1(a)]. These radiative lifetimes are 1000× faster compared to those measured in indirect-gap o-SL's (τ ≈ 5.5 µs at T = 2 K) [16].…”

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confidence: 69%

Electronic Structure of Intentionally Disordered AlAs/GaAs Superlattices

1995

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We use realistic pseudopotentials and a plane-wave basis to study the electronic structure of non-periodic, three-dimensional, 2000-atom (AlAs) n /(GaAs) m (001) superlattices, where the individual layer thicknesses n, m ∈ {1, 2, 3} are randomly selected. We find that while the band gap of the equivalent (n = m = 2) ordered superlattice is indirect, random fluctuations in layer thicknesses lead to a direct gap in the planar Brillouin zone, strong wavefunction localization along the growth direction, short radiative lifetimes, and a significant band-gap reduction, in agreement with experiments on such intentionally grown disordered superlattices. PACS numbers: 73.20.Dx,78.66.-w,71.50.+t Typeset using REVT E X 1 Ordered semiconductor superlattices-produced routinely by epitaxial crystal growth techniques-are widely recognized for their unique electronic and optical properties [1]. To tailor the electronic properties (e.g., through band folding) one aims at growing ordered superlattices (o-SL) with definite values of the thicknesses n and m in (A) n /(G) m . One could, however, deliberately grow a disordered superlattice (d-SL) [2,3], where the individual layer thicknesses n, m, n ′ , m ′ , n ′′ , m ′′ , . . . are selected at random according to a given probability distribution p α (n) (α = A, G). While the electronic structure of an o-SL is characterized by extended states and the formation of mini-bands, a truly one-dimensional disordered system (described, e.g., by the Anderson model) shows carrier localization and absence of dispersion [4,5]. Sasaki et al. [3] grew ∼1000 monolayer (ML) thick AlAs/GaAs d-SL's (i.e., A = AlAs, G = GaAs) with n and m chosen from a set of small integers {1, 2, 3}, viz., p A = p G = p, with p(1) = p(2) = p(3) = 1 3 . Since the average layer thickness is 2 monolayers, one can think of this d-SL as evolving from an (A) 2 /(G) 2 o-SL by random substitution of A 2 and G 2 layers by A 1 , A 3 , G 1 , and G 3 layers ("δ-doping"). Such disordered superlattices have shown surprising and unique optical properties relative to their parent o-SL [3]: (a) strong and initially fast decaying (lifetime τ = 0.25 ns at T = 77 K) photoluminescence (PL) intensity even though the equivalent o-SL has an indirect band gap and thus emits both weakly and slowly, (b) a large red shift (∼60 meV) of the PL peak with respect to the equivalent o-SL, and (c) an order of magnitude slower rate of reduction of the PL intensity with temperature. These unusual properties of d-SL's appear very attractive for optoelectronic applications [3].In modelling the electronic structure of a d-SL [2,6,7], one faces difficulties arising from the existence of two entirely different length scales: (i) The lack of translational symmetry requires the use of unit cells with a macroscopic length N ≈ 1000 ML, equal to the total length of the d-SL (Nd ≈ 300 nm, where d is the monolayer thickness). (ii) The spatial variations of the electron potential, however, occur on a microscopic length scale of about 0.1 nm. While it is possible to re...

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GaAs/AlAs Superlattices and the Tight-Binding Model

Helmholz

Voon

2002

phys. stat. sol. (b)

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A study of how well tight-binding models can reproduce the optoelectronic properties of GaAs/ AlAs superlattices is carried out. It is shown that two key parameter sets lead to observable differences in the pseudo-direct energy gap regime, as well as in the direct gap regime. In addition to the differences in bulk fitting, other less direct differences, such as wave function localization, are found to play a role.

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Electronic states in GaAs-AlAs short-period superlattices: energy levels and symmetry

Cited by 33 publications

References 62 publications

Binding Graphene Sheets Together Using Silicon: Graphene/Silicon Superlattice

Binding Graphene Sheets Together Using Silicon: Graphene/Silicon Superlattice

Electronic Structure of Intentionally Disordered AlAs/GaAs Superlattices

GaAs/AlAs Superlattices and the Tight-Binding Model

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