Comparison of atomistic and continuum theoretical approaches to determine electronic properties of GaN/AlN quantum dots

Abstract

In this work we present a comparison of multiband k · p models, the effective bond-orbital approach, and an empirical tight-binding model to calculate the electronic structure for the example of a truncated pyramidal GaN/AlN self-assembled quantum dot with a zincblende structure. For the system under consideration, we find a very good agreement between the results of the microscopic models and the 8-band k · p formalism, in contrast to a 6+2-band k·p-model, where conduction band and valence band are assumed to be decoupled. This indicates a surprisingly strong coupling between conduction and valence band states for the wide band gap materials GaN and AlN. Special attention is paid to the possible influence of the weak spin-orbit coupling on the localized single-particle wave functions of the investigated structure.

Anisotropic optical response of GaN and AlN nanowires

“…A great variety of implementations of this method are available in the literature, depending on the basis functions size or the number of neighbor atoms for which the interaction is taken into account. Thus, we can find implementations with a small basis (s c p 3 a ) in the modeling of GaN/AlN quantum dots, with a good agreement at Γ-point, in comparison with results of the k · p method, [34] or studies of nitride bulk band structure with a very large basis, sps * d, of twenty orbitals per atom, giving a precise description of most of the points of the Brillouin zone. [35,36] In this work, we employ an sp 3 implementation that uses eight orbitals per atom (the spin-orbit interaction is included following Ref.…”

Tight‐binding model for the electronic and optical properties of nitride‐based quantum dots

“…While the calculated EBOM and ETBM bulk band structures are in excellent agreement around the G-point, we find deviations around the X-point [44]. Although the lateral dimension of the QD structure is large, it is very thin (%2 nm) along the growth direction.…”

“…A detailed discussion of the ETBM and the EBOM approach applied to the zincblende system is given in Refs. [44,45]. Assuming that only the uppermost valence bands and the lowest conduction bands are relevant for a description of the electronic properties of the bulk semiconductor systems of interest, we use a localized sp 3 basis ja; Ri, i.e., one s-state (a ¼ s) and three p-states (a ¼ p x ; p y ; p z ) per spin direction at each site R. Here one can already introduce and describe the difference between the fully atomistic ETBM (from here on briefly denoted ETBM) and the EBOM.…”

“…As discussed in detail in Ref. [44], the first two hole states are split by about 6 meV due to the underlying zincblende structure and the spin-orbit coupling. These two effects strongly modify the optical properties of a truncated pyramidal GaN/AlN QD with a zincblende structure, as we will discuss in detail in the following section.…”

Growth process, characterization, and modeling of electronic properties of coupled InAsSbP nanostructures

“…Moreover, we have previously evaluated the validity of the employed model for GaN/AlN QDs of smaller characteristic dimensions and were able to achieve an excellent agreement with atomistic tight-binding calculations. 17 The parameters required for the calculation of the electronic properties were also taken from Ref. 15.…”