Atomically resolved structure of InAs quantum dots

Márquez, Juan Carlos Parra; Geelhaar, Lutz; Jacobi, K.

doi:10.1063/1.1365101

Cited by 167 publications

(91 citation statements)

References 18 publications

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“…19 The S-K island has been reported to have facets. [19][20][21][22] The islands of the present study also probably have facets, and the obtained elliptical AFM image can reflect this.…”

Section: Discussionsupporting

confidence: 60%

Size, density, and shape of InAs quantum dots in closely stacked multilayers grown by the Stranski–Krastanow mode

Shiramine¹,

Muto²,

Shibayama³

et al. 2003

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Closely stacked multilayer structures of InAs islands with intermediate-layer thicknesses d of 3, 6, 10, and 20 nm were grown by the Stranski-Krastanow mode of molecular beam epitaxy and were observed using transmission electron microscopy ͑TEM͒ and atomic force microscopy ͑AFM͒. The multilayers consisted of five InAs layers each of a thickness of 1.8 monolayers and four GaAs layers each of a thickness d. Columns of coherent islands were observed by cross-sectional TEM. Changes in the size and density of the islands with d, determined by AFM, could be explained in terms of ͑i͒ change in the vertical pairing probability of islands, ͑ii͒ detachment of In from the top of the island, and ͑iii͒ surface segregation of In. The observed AFM images of the islands were elliptical. Their major axis was in the ͓110͔ direction, and the length of the minor axis was 80% of that of the major axis.

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“…19 The S-K island has been reported to have facets. [19][20][21][22] The islands of the present study also probably have facets, and the obtained elliptical AFM image can reflect this.…”

Section: Discussionsupporting

confidence: 60%

Size, density, and shape of InAs quantum dots in closely stacked multilayers grown by the Stranski–Krastanow mode

Shiramine¹,

Muto²,

Shibayama³

et al. 2003

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…We calculated that 79% of the intensity along this curve is concentrated within a region of size -15 nm ≤ x ≤ 15 nm. Hence, the bowtie geometry is capable of focusing light into spatial regions, similar to the lateral dimension of a single self-assembled InGaAs quantum dot 35 . Besides the electric field distribution, we also calculated the scattering cross section σ of the nanoantenna, which is defined as P = σ · I 0 , where I 0 denotes the intensity of the used total field scattered field (TFSF) source and P the measured power of the monitors that completely envelope the bowtie.…”

Section: Fabrication and Experimental Setupmentioning

confidence: 99%

Optical properties and interparticle coupling of plasmonic bowtie nanoantennas on a semiconducting substrate

et al. 2014

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We present the simulation, fabrication and optical characterization of plasmonic gold bowtie nanoantennas on a semiconducting GaAs substrate as geometrical parameters such as size, feed gap, height and polarization of the incident light are varied. The surface plasmon resonance was probed using white light reflectivity on an array of nominally identical, 35 nm thick Au antennas. To elucidate the influence of the semiconducting, high refractive index substrate, all experiments were compared using nominally identical structures on glass. Besides a linear shift of the surface plasmon resonance from 1.08 eV to 1.58 eV when decreasing the triangle size from 170 nm to 100 nm on GaAs, we observed a global redshift by 0.25 ± 0.05 eV with respect to nominally identical structures on glass. By performing polarization resolved measurements and comparing results with finite difference time domain simulations, we determined the near field coupling between the two triangles composing the bowtie antenna to be ∼8× stronger when the antenna is on a glass substrate compared to when it is on a GaAs substrate. The results obtained are of strong relevance for the integration of lithographically defined plasmonic nanoantennas on semiconducting substrates and, therefore, for the development of novel optically active plasmonic-semiconducting nanostructures.

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“…Both spectroscopic and topological information is accessible, and quantum-size objects can be probed in real space with atomic resolution. In particular, there is growing interest in the STM images of quantum dots [4] and sub-surface impurity states in semiconductors [5,6,7,8]. Although the well-accepted Tersoff and Hamann's theory [9] simply relates the tunneling current to the local density of states (LDOS) at the tip position, the interpretation of specific experiments on localized states is still a matter of debate: on the one hand, the interaction between the surface and the quantum object under investigation must be examined; on the other hand, particularly in the case of deep bound-states, the carrier escape toward the extended band states may play a role [7].…”

mentioning

confidence: 99%

STM Images of Subsurface Mn Atoms in GaAs: Evidence of Hybridization of Surface and Impurity States

et al. 2008

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We prove that scanning tunneling microscopy (STM) images of sub-surface Mn atoms in GaAs are formed by hybridization of the impurity state with intrinsic surface states. They cannot be interpreted in terms of bulk-impurity wavefunction imaging. High atomic resolution images obtained using a low-temperature apparatus are compared with advanced, parameter-free tight-binding simulations accounting for both the buckled (110) surface and vacuum electronic properties.PACS numbers: 71.15.Ap, 73.61.Eyi, The development of scanning tunneling microscopy has expended the applications of imaging to new areas of nanosciences and engineering such as atom or molecule identification, manipulation and nanostructuring [1,2,3]. Both spectroscopic and topological information is accessible, and quantum-size objects can be probed in real space with atomic resolution. In particular, there is growing interest in the STM images of quantum dots [4] and sub-surface impurity states in semiconductors [5,6,7,8]. Although the well-accepted Tersoff and Hamann's theory [9] simply relates the tunneling current to the local density of states (LDOS) at the tip position, the interpretation of specific experiments on localized states is still a matter of debate: on the one hand, the interaction between the surface and the quantum object under investigation must be examined; on the other hand, particularly in the case of deep bound-states, the carrier escape toward the extended band states may play a role [7]. In the last few years, acceptors in GaAs have attracted much attention because the shape of the images revealed strong and unexpected chemical signatures: from triangles in the case of shallow acceptors like carbon [7] and zinc [6], to asymmetric butterfly for the deep acceptor manganese [5]. So far, theoretical work has concentrated mostly on comparison of STM images with cross-sections of the bulk impurity wavefunction [5]. In this letter, we report on new experimental data obtained with a low-temperature apparatus and compare these results with advanced TB calculations. We first point that the STM image cannot reflect the LDOS of the impurity: indeed, empty-state STM images show only the group-III elements whereas the neutral acceptor wavefunction is distributed over the different chemical species. In fact, less than 40% of the bulk impurity LDOS shows up in the STM image. Then we prove that the image actually results from the hybridization between intrinsic surface states and the impurity state. A perturbative model is discussed and indicates that a quantitative relation between STM images and bulk wave function is not straightforward. Supercell calculations based on the sp 3 d 5 s * tight binding model and including the (110) surface as well as vacuum are performed and reproduce nicely the experimental images.The sample used in this study was grown by molecular beam epitaxy on a GaAs(001) substrate at 420 C. It consists of two 40 nm-thick GaAs layers doped with 2.1018 Mn cm −3 , embedded between 30 nm-thick GaAs conducting layers doped wi...

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Atomically resolved structure of InAs quantum dots

Cited by 167 publications

References 18 publications

Size, density, and shape of InAs quantum dots in closely stacked multilayers grown by the Stranski–Krastanow mode

Size, density, and shape of InAs quantum dots in closely stacked multilayers grown by the Stranski–Krastanow mode

Optical properties and interparticle coupling of plasmonic bowtie nanoantennas on a semiconducting substrate

STM Images of Subsurface Mn Atoms in GaAs: Evidence of Hybridization of Surface and Impurity States

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