Anomalous suppression of valley splittings in lead salt nanocrystals without inversion center

Poddubny, Alexander N.; Nestoklon, M. O.; Goupalov, S. V.

doi:10.1103/physrevb.86.035324

Cited by 33 publications

(59 citation statements)

References 43 publications

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“…This means that the strong modification of the confined carrier states is a result of resonant enhancement of the mixing between the electron states in the X valley and the hole states in the valley. While the valley mixing, including the -X mixing, is well known in semiconductor nanostructures [30][31][32][33][34][35], in our case the effect is much stronger. The resonant effect for the p orbital might also explain why the radiative rate and band gap energies in Figs.…”

Section: A Electronegative Ligandmentioning

confidence: 67%

Direct band gap silicon quantum dots achieved via electronegative capping

Poddubny

Dohnalová

2014

Phys. Rev. B

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Direct bandgap silicon quantum dots achieved via electronegative capping Poddubny, A.N.; Newell, K. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. We propose a theoretical concept of switching between direct and indirect band gap character in silicon quantum dots (SiQDs) by the use of surface potential induced by the ligands or environment in which SiQDs are immersed-both cases are studied. Theoretical simulations show that the density of states of confined electrons in both real and k space can be dramatically altered by engineering the local electrostatic field. Especially interesting is modification of the lowest excited states, which appear in the valley for electronegative field that "pulls" electrons towards the SiQD surface. Opposite sign of the field does not have such effect at all. Hence we conclude a general trend of promotion of directlike radiative transitions by electronegative capping/environment. The rates are enhanced by more than two orders of magnitude compared to "normal" SiQDs, which can be as high as the values characteristic for direct band gap semiconductors. This model is in agreement with observed experimental properties of SiQDs with covalently bonded electronegative ligands.

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Section: A Electronegative Ligandmentioning

confidence: 67%

Direct band gap silicon quantum dots achieved via electronegative capping

Poddubny

Dohnalová

2014

Phys. Rev. B

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“…This is expected because the corresponding states can mix only with the states of the same symmetry and there are The reciprocal space LDOS analysis can be used to trace the dependence of the valley splittings on the NW diameter. This dependence is highly oscillating, which is explained by the fact that even a small variation in the NW radius results in substantially different arrangements of the surface atoms, similar to the quantum dot case [29,50]. In Fig.…”

Section: 6mentioning

confidence: 80%

“…The spinorbit interaction is introduced following Chadi [42]. The tight-binding parameters [29] are chosen to accurately reproduce experimental effective masses at the L point as well as the electron energies at the high-symmetry points of the Brillouin zone which were calculated in Ref. [33] using the GW -approximation.…”

Section: Tight-binding Methodsmentioning

confidence: 99%

Valley and spin splittings in PbSe nanowires

et al. 2017

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We use an empirical tight-binding approach to calculate electron and hole states in [111]-grown PbSe nanowires. We show that the valley-orbit and spin-orbit splittings are very sensitive to the atomic arrangement within the nanowire elementary cell and differ for [111]-nanowires with microscopic $D_{3d}$, $C_{2h}$ and $D_{3}$ symmetries. For the nanowire diameter below 4 nm the valley-orbit splittings become comparable with the confinement energies and the $\boldsymbol{k}\cdot\boldsymbol{p}$ method is inapplicable. Nanowires with the $D_{3}$ point symmetry having no inversion center exhibit giant spin splitting $E = \alpha k_z$, linear in one-dimensional wave vector $k_z$, with the constant $\alpha$ up to 1 eV$\cdot$\AA.Comment: 15 pages, 9 figure

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“…Appendix A: Microscopic wire structure PbSe has the rocksalt crystal structure with a 1 = a 2 (1, 0, 1) , a 2 = a 2 (1, 1, 0) , a 3 = a 2 (0, 1, 1) (A1) lattice vectors, where a = 6.1Å is the lattice constant [26]. Reciprocal lattice vectors are conveniently related with the L valleys 1 as b µ = 2k µ , µ = 1, 2, 3.…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…The first one is readily incorporated in the k · p and splits the valley multiplets in NWs only partially [21]. The second one fully removes the valley degeneracy and can be included in the k · p phenomenologically [23], but for careful theoretical description it requires an atomistic approach [24,25] as it is very sensitive to the microscopic structure of the NW [26,27].…”

Section: Introductionmentioning

confidence: 99%

Shape effect on the valley splitting in lead selenide nanowires

Avdeev

2019

Phys. Rev. B

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We study the cross-section shape and size effects on the valley splitting in PbSe nanowires within the framework of empirical sp 3 d 5 s * tight-binding method. We consider ideallized prismatic nanowires, grown along [110], with the cross-section shape varying from rectangular (terminated by {001} and {110} facets) to rhombic (terminated mostly by {111} facets). The valley splitting energies have the maximal value (up to hundreds meV) in rectangular nanowires, while in rhombic ones they are almost absent. The shape dependence is shown to be similar for a wide range cross-section sizes and different point symmetries of nanowires. arXiv:1901.09773v1 [cond-mat.mes-hall]

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Anomalous suppression of valley splittings in lead salt nanocrystals without inversion center

Cited by 33 publications

References 43 publications

Direct band gap silicon quantum dots achieved via electronegative capping

Direct band gap silicon quantum dots achieved via electronegative capping

Valley and spin splittings in PbSe nanowires

Shape effect on the valley splitting in lead selenide nanowires

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