We investigate the electronic band structure of modulationdoped GaAs/AlGaAs coreshell nanowires for both n and pdoping. We developed an 8band BurtForeman k.p Hamiltonian approach to describe coupled conduction and valence bands in heterostructured nanowires of arbitrary composition, growth directions, and doping. Coulomb interactions with the electron/hole gas are taken into account within a meanfield selfconsistent approach. We map the ensuing multiband envelope function and Poisson equations to optimized, nonuniform realspace grids by the finite element method. Selfconsistent charge density, singleparticle subbands, density of states and absorption spectra are obtained at different doping regimes. For ndoped samples, the large restructuring of the electron gas for increasing doping results in the formation of quasi1D electron channels at the coreshell interface. Strong heavyhole/lighthole coupling of hole states leads to non parabolic dispersions with mass inversion, similarly to planar structures, which persist at large dopings, giving rise to direct LH and indirect HH gaps. In pdoped samples the hole gas forms an almost isotropic, ringlike cloud for a large range of doping. Here, as a result of the increasing localization, HH and LH states uncouple, and mass inversion takes place at a threshold density. A similar evolution is obtained at fixed doping as a function of temperature. We show that signatures of the evolution of the band structure can be singled out in the anisotropy of linearly polarized optical absorption.
We investigate the electronic band structure of modulationdoped GaAs/AlGaAs coreshell nanowires for both n and p doping. We developed an 8band BurtForeman k·p Hamiltonian approach to describe coupled conduction and valence bands in heterostructured nanowires of arbitrary composition, growth directions, and doping. Coulomb interactions with the electron/hole gas are taken into account within a meanfield selfconsistent approach. We map the ensuing multiband envelope function and Poisson equations to optimized, nonuniform realspace grids by the finite element method. Selfconsistent chargedensity, singleparticle subbands, density of states, and absorption spectra are obtained at different doping regimes. For ndoped samples, the large restructuring of the electron gas for increasing doping results in the formation of quasionedimensional electron channels at the coreshell interface. Strong heavyhole (HH)/lighthole (LH) coupling of hole states leads to nonparabolic dispersions with mass inversion, similarly to planar structures, which persist at large dopings, giving rise to direct LH and indirect HH gaps. In pdoped samples the hole gas forms an almost isotropic, ringlike cloud for a large range of doping. Here as a result of the increasing localization, HH and LH states uncouple, and mass inversion takes place at a threshold density. A similar evolution is obtained at fixed doping as a function of temperature. We show that signatures of the evolution of the band structure can be singled out in the anisotropy of linearly polarized optical absorption.
Band structure of n  and p doped coreshell nanowires / Vezzosi, A.; Bertoni, A.; Goldoni, G..  In: PHYSICAL REVIEW. B.  ISSN 24699950.  105:24(2022), pp. N/AN/A. [10.1103/PhysRevB.105.245303]
Band structure of n  and p doped coreshell nanowires
Goldoni G.
2022
Abstract
We investigate the electronic band structure of modulationdoped GaAs/AlGaAs coreshell nanowires for both n and p doping. We developed an 8band BurtForeman k·p Hamiltonian approach to describe coupled conduction and valence bands in heterostructured nanowires of arbitrary composition, growth directions, and doping. Coulomb interactions with the electron/hole gas are taken into account within a meanfield selfconsistent approach. We map the ensuing multiband envelope function and Poisson equations to optimized, nonuniform realspace grids by the finite element method. Selfconsistent chargedensity, singleparticle subbands, density of states, and absorption spectra are obtained at different doping regimes. For ndoped samples, the large restructuring of the electron gas for increasing doping results in the formation of quasionedimensional electron channels at the coreshell interface. Strong heavyhole (HH)/lighthole (LH) coupling of hole states leads to nonparabolic dispersions with mass inversion, similarly to planar structures, which persist at large dopings, giving rise to direct LH and indirect HH gaps. In pdoped samples the hole gas forms an almost isotropic, ringlike cloud for a large range of doping. Here as a result of the increasing localization, HH and LH states uncouple, and mass inversion takes place at a threshold density. A similar evolution is obtained at fixed doping as a function of temperature. We show that signatures of the evolution of the band structure can be singled out in the anisotropy of linearly polarized optical absorption.File  Dimensione  Formato  

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