Self-assembling and Ordering of Ge/Si Quantum Dots on Flat and Nanostructured Surfaces

2001 ◽  
Vol 696 ◽  
Author(s):  
N. Motta ◽  
A. Sgarlata ◽  
A. Balzarotti ◽  
F. Rosei
Keyword(s):  
Quantum Dots ◽  
Average Distance ◽  
Self Organization ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Step Bunching ◽  
Nanostructured Surfaces ◽  
Self Assembling ◽  
Flash Annealing ◽  
Si Quantum Dots

AbstractWe have studied by Scanning Tunneling Microscopy (STM) the effect of step bunching on Ge/Si(111) epitaxy. We have verified that self-organization of Ge islands is greatly influenced by “step bunching” which arises from the flash-annealing procedure used to reconstruct the Si surface. Two different growth regimes arise: initially islands nucleate and evolve only at steps, up to complete ripening; subsequently the same evolution is observed on flat areas of the sample. The average distance between islands and steps is nearly constant, originating a single row of equally spaced islands, followed by other rows of islands in between. The exploitation of this phenomenon, which is governed by the surface diffusion length of Ge on Si (estimated from our data) and by the terrace width, constitutes one possible path to achieve self-organization of quantum dots.

Self-Assembling and Ordering of Ge/Si Quantum Dots on Flat and Nanostructured Surfaces

2001 ◽  
Vol 707 ◽  
Author(s):  
N. Motta ◽  
A. Sgarlata ◽  
A. Balzarotti ◽  
F. Rosei
Keyword(s):  
Quantum Dots ◽  
Average Distance ◽  
Self Organization ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Step Bunching ◽  
Nanostructured Surfaces ◽  
Self Assembling ◽  
Flash Annealing ◽  
Si Quantum Dots

ABSTRACTWe have studied by Scanning Tunneling Microscopy (STM) the effect of step bunching on Ge/Si(111) epitaxy. We have verified that self-organization of Ge islands is greatly influenced by “step bunching” which arises from the flash-annealing procedure used to reconstruct the Si surface. Two different growth regimes arise: initially islands nucleate and evolve only at steps, up to complete ripening; subsequently the same evolution is observed on flat areas of the sample. The average distance between islands and steps is nearly constant, originating a single row of equally spaced islands, followed by other rows of islands in between. The exploitation of this phenomenon, which is governed by the surface diffusion length of Ge on Si (estimated from our data) and by the terrace width, constitutes one possible path to achieve self-organization of quantum dots.

OPTICAL AND STRUCTURAL ANALYSIS OF Ge/Si QUANTUM DOTS GROWN ON A Si(001) SURFACE COVERED WITH A SiO2 SUB-MONOLAYER

2007 ◽  
Vol 06 (03n04) ◽  
pp. 245-248
Author(s):  
A. FONSECA ◽  
E. ALVES ◽  
J. P. LEITÃO ◽  
N. A. SOBOLEV ◽  
M. C. CARMO ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Molecular Beam ◽  
Broad Band ◽  
Sample Surface ◽  
High Energy ◽  
Scanning Tunneling ◽  
Hydrogen Passivation ◽  
Tunneling Microscopy ◽  
Grazing Angles ◽  
Si Quantum Dots

In this work we performed measurements of photoluminescence (PL), scanning tunneling microscopy (STM), and Rutherford backscattering (RBS) at grazing angles of incidence in a set of samples grown by molecular beam epitaxy, in which a Ge layer was deposited on a Si (001) substrate covered with a thin SiO 2 layer. Three different thicknesses for either layer were deposited: 0.5, 0.75 or 1 monolayer (ML) of SiO 2, and 0.3, 0.6 or 0.9 nm of Ge . The PL measurements for the samples with thicker layers show a broad band at ~ 0.85 eV superimposed on a dislocation related band at ~ 0.81 eV . The attribution of the high energy band to Ge islands in this sample is supported by STM and RBS measurements, as well as by PL measurements after hydrogen passivation of the sample surface. For the samples with thinner SiO 2 and Ge layers, no evidence for the formation of Ge islands was found.

scholarly journals Structural and compositional analysis of (InGa)(AsSb)/GaAs/GaP Stranski–Krastanov quantum dots

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Raja S. R. Gajjela ◽  
Arthur L. Hendriks ◽  
James O. Douglas ◽  
Elisa M. Sala ◽  
Petr Steindl ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Flash Memory ◽  
Compositional Analysis ◽  
Structural Data ◽  
Scanning Tunneling ◽  
Valuable Insight ◽  
Material System ◽  
Tunneling Microscopy ◽  
Cross Sectional ◽  
Fe Simulations

AbstractWe investigated metal-organic vapor phase epitaxy grown (InGa)(AsSb)/GaAs/GaP Stranski–Krastanov quantum dots (QDs) with potential applications in QD-Flash memories by cross-sectional scanning tunneling microscopy (X-STM) and atom probe tomography (APT). The combination of X-STM and APT is a very powerful approach to study semiconductor heterostructures with atomic resolution, which provides detailed structural and compositional information on the system. The rather small QDs are found to be of truncated pyramid shape with a very small top facet and occur in our sample with a very high density of ∼4 × 1011 cm−2. APT experiments revealed that the QDs are GaAs rich with smaller amounts of In and Sb. Finite element (FE) simulations are performed using structural data from X-STM to calculate the lattice constant and the outward relaxation of the cleaved surface. The composition of the QDs is estimated by combining the results from X-STM and the FE simulations, yielding ∼InxGa1 − xAs1 − ySby, where x = 0.25–0.30 and y = 0.10–0.15. Noticeably, the reported composition is in good agreement with the experimental results obtained by APT, previous optical, electrical, and theoretical analysis carried out on this material system. This confirms that the InGaSb and GaAs layers involved in the QD formation have strongly intermixed. A detailed analysis of the QD capping layer shows the segregation of Sb and In from the QD layer, where both APT and X-STM show that the Sb mainly resides outside the QDs proving that Sb has mainly acted as a surfactant during the dot formation. Our structural and compositional analysis provides a valuable insight into this novel QD system and a path for further growth optimization to improve the storage time of the QD-Flash memory devices.

Scanning tunneling microscopy of step bunching on vicinal GaAs(100) annealed at high temperatures

1994 ◽  
Vol 65 (6) ◽  
pp. 722-724 ◽  
Author(s):  
S. L. Skala ◽  
S. T. Chou ◽  
K.‐Y. Cheng ◽  
J. R. Tucker ◽  
J. W. Lyding
Keyword(s):  
Scanning Tunneling Microscopy ◽  
High Temperatures ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Step Bunching

scholarly journals Исследование электрофизических свойств квантовых точек антимонида индия: значение формы

2021 ◽  
Vol 55 (3) ◽  
pp. 237
Author(s):  
В.Ф. Кабанов ◽  
А.И. Михайлов ◽  
М.В. Гавриков
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Indium Antimonide ◽  
Spectral Characteristics ◽  
Characteristic Size ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Transmission Electron ◽  
Particle Size Analyzer ◽  
Characteristics Analysis

In this work, we studied the influence of the shape of the indium antimonide quantum dots of on some important electrophysical parameters by spectral characteristics analysis, transmission electron microscopy, scanning tunneling microscopy, a laser particle size analyzer, and scanning electron microscopy. It is shown that the real form of quantum dots (spherical and cubic models) at the same characteristic size will noticeably affect the energy spectrum of the investigated objects and, accordingly, their electrophysical and optical properties.

Graphene Quantum Dots Probed by Scanning Tunneling Microscopy

2017 ◽  
Vol 529 (11) ◽  
pp. 1700018 ◽  
Author(s):  
Markus Morgenstern ◽  
Nils Freitag ◽  
Alexander Nent ◽  
Peter Nemes-Incze ◽  
Marcus Liebmann
Keyword(s):  
Quantum Dots ◽  
Scanning Tunneling Microscopy ◽  
Graphene Quantum Dots ◽  
Scanning Tunneling ◽  
Tunneling Microscopy
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