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Abbarchi M, Mano T, Kuroda T, Ohtake A, Sakoda K. Polarization Anisotropies in Strain-Free, Asymmetric, and Symmetric Quantum Dots Grown by Droplet Epitaxy. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:443. [PMID: 33578657 PMCID: PMC7916409 DOI: 10.3390/nano11020443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 01/29/2021] [Accepted: 02/02/2021] [Indexed: 11/17/2022]
Abstract
We provide an extensive and systematic investigation of exciton dynamics in droplet epitaxial quantum dots comparing the cases of (311)A, (001), and (111)A surfaces. Despite a similar s-shell exciton structure common to the three cases, the absence of a wetting layer for (311)A and (111)A samples leads to a larger carrier confinement compared to (001), where a wetting layer is present. This leads to a more pronounced dependence of the binding energies of s-shell excitons on the quantum dot size and to the strong anti-binding character of the positive-charged exciton for smaller quantum dots. In-plane geometrical anisotropies of (311)A and (001) quantum dots lead to a large electron-hole fine interaction (fine structure splitting (FSS) ∼100 μeV), whereas for the three-fold symmetric (111)A counterpart, this figure of merit is reduced by about one order of magnitude. In all these cases, we do not observe any size dependence of the fine structure splitting. Heavy-hole/light-hole mixing is present in all the studied cases, leading to a broad spread of linear polarization anisotropy (from 0 up to about 50%) irrespective of surface orientation (symmetry of the confinement), fine structure splitting, and nanostructure size. These results are important for the further development of ideal single and entangled photon sources based on semiconductor quantum dots.
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Affiliation(s)
- Marco Abbarchi
- Aix Marseille Univ, Université de Toulon, CNRS, IM2NP Marseille, France
| | - Takaaki Mano
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; (T.M.); (T.K.); (A.O.); (K.S.)
| | - Takashi Kuroda
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; (T.M.); (T.K.); (A.O.); (K.S.)
| | - Akihiro Ohtake
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; (T.M.); (T.K.); (A.O.); (K.S.)
| | - Kazuaki Sakoda
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; (T.M.); (T.K.); (A.O.); (K.S.)
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Abuwaar ZY, Wang ZM, Lee JH, Salamo GJ. Observation of Ga droplet formation on (311)A and (511)A GaAs surfaces. NANOTECHNOLOGY 2006; 17:4037-40. [PMID: 21727534 DOI: 10.1088/0957-4484/17/16/007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Using (100) GaAs substrates as a reference, we present a study of the formation of Ga droplets on (311)A and (511)A GaAs substrates in which the effect of both the substrate temperature and the amount of Ga supplied on the droplet density and height for the three different surfaces have been investigated. Droplets on (100) substrates show a round shape; however, they appear as elongated balls with tails along the [Formula: see text] direction of the (311)A substrate and the [Formula: see text] direction of the (511)A substrate. It has been found that the Ga droplets on (511)A surfaces have lower densities and higher heights than those on (100) substrates. In contrast, Ga droplets on (311)A surfaces have lower heights and much higher densities compared to those for both (100) and (511)A. We observed that the decrease in the droplet density with increasing growth temperature for both (311)A and (511)A is more than twice that for the (100)GaAs surface due to the larger drop in the nucleation rate. Based on these observations, we offer a physical explanation based on the thermodynamics and the anisotropy of the high-index surfaces.
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Affiliation(s)
- Ziad Y Abuwaar
- Department of Physics, University of Arkansas, Fayetteville, AR 72701, USA
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Csáthy GA, Noh H, Tsui DC, Pfeiffer LN, West KW. Magnetic-field-induced insulating phases at large r s. PHYSICAL REVIEW LETTERS 2005; 94:226802. [PMID: 16090424 DOI: 10.1103/physrevlett.94.226802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Indexed: 05/03/2023]
Abstract
Exploring a two-dimensional hole system in the large r(s) regime we found a surprisingly rich phase diagram. At the highest densities, beside the nu =1/3, 2/3, and 2/5 fractional quantum Hall states, we observe both of the previously reported high field insulating and reentrant insulating phases. As the density is lowered, the reentrant insulating phase initially strengthens, then it unexpectedly starts weakening until it completely disappears. The intricate behavior of the insulating phases can be explained by a nonmonotonic melting line in the nu-r(s) phase space.
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Affiliation(s)
- G A Csáthy
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA
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Geelhaar L, Márquez J, Kratzer P, Jacobi K. GaAs(2 5 11): a new stable surface within the stereographic triangle. PHYSICAL REVIEW LETTERS 2001; 86:3815-3818. [PMID: 11329331 DOI: 10.1103/physrevlett.86.3815] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2000] [Indexed: 05/23/2023]
Abstract
The atomic structure of GaAs(2 5 11), a hitherto unknown stable surface, has been determined by in situ scanning tunneling microscopy and first-principles electronic structure calculations. This orientation is located within the stereographic triangle, i.e., far away from all low-index surfaces. A low-energy ( 1x1) reconstruction containing arsenic dimers forms on the surface. The analysis of the surface structure shows that, for semiconductor surfaces, the gain in stability due to minimization of the number of dangling bonds is more important than the gain from rendering a semiconducting ground state.
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Affiliation(s)
- L Geelhaar
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
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Tutuc E, De Poortere EP, Papadakis SJ, Shayegan M. In-plane magnetic field-induced spin polarization and transition to insulating behavior in two-dimensional hole systems. PHYSICAL REVIEW LETTERS 2001; 86:2858-2861. [PMID: 11290057 DOI: 10.1103/physrevlett.86.2858] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2000] [Indexed: 05/23/2023]
Abstract
Using a novel technique, we make quantitative measurements of the spin polarization of dilute [ (3.4-6.8)x10(10) cm(-2)] GaAs (311)A two-dimensional holes as a function of an in-plane magnetic field. As the field is increased the system gradually becomes spin polarized, with the degree of spin polarization depending on the orientation of the field relative to the crystal axes. Moreover, the behavior of the system turns from metallic to insulating before it is fully spin polarized. The minority-spin population at the transition is approximately 8x10(9) cm(-2), close to the density below which the system makes a transition to an insulating state in the absence of a magnetic field.
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Affiliation(s)
- E Tutuc
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA
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Márquez J, Kratzer P, Geelhaar L, Jacobi K, Scheffler M. Atomic Structure of the Stoichiometric GaAs(114) Surface. PHYSICAL REVIEW LETTERS 2001; 86:115-118. [PMID: 11136107 DOI: 10.1103/physrevlett.86.115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2000] [Indexed: 05/23/2023]
Abstract
The stoichiometric GaAs(114) surface has been prepared using molecular beam epitaxy followed by annealing in ultrahigh vacuum. Based on in situ scanning tunneling microscopy measurements and first-principles electronic-structure calculations, we determine the surface reconstruction which we call alpha2(2x1). Contrary to what is expected for a high-index surface, it is surprisingly elementary. The (2x1) unit cell contains two As dimers and two rebonded Ga atoms. The surface energy is calculated as 53 meV/Å(2), which falls well within the range of low-index GaAs surface energies.
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Affiliation(s)
- J Márquez
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
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Papadakis SJ, Shayegan M, Winkler R. Anisotropic magnetoresistance of two-dimensional holes in GaAs. PHYSICAL REVIEW LETTERS 2000; 84:5592-5595. [PMID: 10991002 DOI: 10.1103/physrevlett.84.5592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/1999] [Indexed: 05/23/2023]
Abstract
Experiments on high-quality GaAs (311)A two-dimensional holes at low temperatures reveal a remarkable dependence of the magnetoresistance, measured with an in-plane magnetic field ( B), on the direction of B relative to both the crystal axes and the current direction. The magnetoresistance features, and in particular the value of B above which the resistivity exhibits an insulating behavior, depend on the orientation of B. To explain the data, the anisotropic band structure of the holes and a repopulation of the spin subbands in the presence of B, as well as the coupling of the orbital motion to B, need to be taken into account.
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Affiliation(s)
- SJ Papadakis
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
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Sanguinetti S, Chiantoni G, Miotto A, Grilli E, Guzzi M, Henini M, Polimeni A, Patane A, Eaves L, Main PC. Self-assembling of In(Ga)As/GaAs quantum dots on (N11) substrates: the (311)A case. Micron 2000; 31:309-13. [PMID: 10702981 DOI: 10.1016/s0968-4328(99)00098-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have investigated the In(Ga)As island formation, in the Stranski-Krastanov growth mode, on (311)A GaAs substrates. The surface topography of InAs and InGaAs strained epilayers was studied by contact microscopies. The different substrate affects the overgrown island shape. In(Ga)As grown on (311)A gives rise to quantum wire-like islands. Quantum dots (QDs), but with highly anisotropic shapes, are the outcomes of InAs deposition. QD samples were also characterized by photoluminescence (PL) measurements. Correlation between optical and morphological properties was observed.
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Pusep YA, Galzerani JC, Pimenta MA, Lubyshev DI, Basmaji P. Raman study of interface roughness in (GaAs)n/(AlAs)n superlattices grown on tilted surfaces: Evidence of corrugation of the (113) interface. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:1927-1932. [PMID: 9983653 DOI: 10.1103/physrevb.53.1927] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Popovic ZV, Vukmirovic MB, Raptis YS, Anastassakis E, Nötzel R, Ploog K. Folded phonons from lateral periodicity in (311) GaAs/AlAs corrugated superlattices. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:5789-5794. [PMID: 9981768 DOI: 10.1103/physrevb.52.5789] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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