Impact of Random Dopant Fluctuations on the Electronic Properties of In_xGa_1–xN/GaN Axial Nanowire Heterostructures

Abstract

We study the electronic properties of axial In(x)Ga(1-x)N/GaN nanowire heterostructures with randomly placed ionized donors. Our simulations are based on an eight-band k·p model and indicate large variations of both the ground state transition energy and the spatial distribution of the electron and hole charge density. We show that these variations are intrinsic to nanostructures containing ionized donors and that the presence of donors has important consequences for all nanowire-based light-emitting devices including single-photon emitters required for quantum computing and quantum cryptography.

Radial Stark Effect in (In,Ga)N Nanowires

“…The experimentally observed presence of radial electric fields 20,21 is accompanied by strong carrier localization. 22,23 This localization may occur at compositional fluctuations in the ternary alloy [22][23][24][25][26][27][28][29] or at random dopant fluctuations in the nanowire 30 and may result in individual electron and hole localization at random spatial positions.…”

“…In addition, (In,Ga)N nanowires may exhibit large densities of stacking faults, 42 which induce charge carrier localization along the nanowire axis, 43,44 and the random distribution of dopants in these nanoscale structures can also localize charge carriers. 30 To get a deeper insight into the localization and recombination dynamics of charge car-riers in our nanowires, we have carried out temperature-dependent photoluminescence experiments. Figure 3(a) displays the photoluminescence spectra taken between 10 and 230 K on the undoped nanowire ensemble for T sub = 640 • C. Similar experiments carried out on the undoped nanowires grown at T sub = 590 °C are shown in the Supplementary Information (Fig.…”

“…As a result, electrons and holes are localized at opposite interfaces of the quantum well, and the associated redshift of the transition energy as well as the reduction in the overlap of electron and hole wave functions are commonly referred to as quantum-confined Stark effect. , In group-III nitride nanowires, a similar spatial separation of electrons and holes can result from the radial electric fields that accompany the surface band bending as a consequence of the Fermi level pinning at the lateral surface of the nanowires. − In particular, in GaN nanowires, this separation can be large enough to significantly reduce the wave function overlap and lead to a quenching of the nanowire photoluminescence intensity. , The situation becomes even more complex when considering the case of (In,Ga)N nanowires. The experimentally observed presence of radial electric fields , is accompanied by strong carrier localization. , This localization may occur at compositional fluctuations in the ternary alloy − or at random dopant fluctuations in the nanowire and may result in individual electron and hole localization at random spatial positions.…”

Polar ( In , Ga ) N / Tanner1, Dawson2, Kappers3 et al. 2020Phys. Rev. Applied

“…Furthermore, similar approaches have been used by other groups to study the optical properties of different nitridebased nanostructures. 65,66 Given that each electron and hole wave function is connected to a corresponding eigenenergy, one can also study an energy resolved modulus wave function overlap Ω eh (E e n , E h m ) where E e n is the electron eigenenergy and E h m is the hole eigenenergy of states n and m, respectively. Therefore, Ω eh (E e n , E h m ) can be visualized as a function of electron E e n and hole E h m energies.…”

Multiband k·p model and fitting scheme for ab initio based electronic structure parameters for wurtzite GaAs

“…The development of novel electronic devices and light sources requires efficient techniques to model the optoelectronic properties of semiconductor nanostructures. For about two decades now, the six-and eight-band k • p formalisms represent the backbone of semiconductor device modeling and have been extensively employed to study semiconductor nanostructures of a wide range of shapes, dimensions, and material compositions [1][2][3][4][5][6]. These approaches describe the bulk electronic band structure of a material perturbatively, such that it is well reproduced in the vicinity of a selected highsymmetry point within the Brillouin zone (BZ), commonly the zone center .…”