scholarly journals Epitaxial Growth of Optoelectronically Active Ga(As)Sb Quantum Dots on Al-Rich AlGaAs with GaAs Capsule Layers

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Johannes Strassner ◽  
Johannes Richter ◽  
Thomas Loeber ◽  
Christoph Doering ◽  
Henning Fouckhardt
Keyword(s):  
Quantum Dots ◽  
Semiconductor Lasers ◽  
Growth Front ◽  
Material System ◽  
Additional Degree ◽  
Barrier Layers ◽  
System A ◽  
Storage Cells ◽  
Mere Existence ◽  
Design Freedom

We present a study of optoelectronically active Ga(As)As quantum dots (QDs) on Al-rich AlxGa1-xAs layers with Al concentrations up to x = 90%. So far, however, it has not been possible to grow optoelectronically active Ga(As)As QDs epitaxially directly on and in between Al-rich barrier layers in the AlGaInAsSb material system. A QD morphology might appear on the growth front, but the QD-like entities will not luminesce. Here, we use photoluminescence (PL) measurements to show that thin Al-free capsule layers between Al-rich barrier layers and the QD layers can solve this problem; this way, the QDs become optoelectronically active; that is, the dots become QDs. We consider antimonide QDs, that is, Ga(As)Sb QDs, either on GaAs for comparison or on AlxGa1-xAs barriers (x >10%) with GaAs capsule layers in between. We also discuss the influence of QD coupling both due to stress/strain from neighboring QDs and quantum-mechanically on the wavelength of the photoluminescence peak. Due to their mere existence, the capsule layers alter the barriers by becoming part of them. Quantum dots applications such as QD semiconductor lasers for spectroscopy or QDs as binary storage cells will profit from this additional degree of design freedom.

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.

scholarly journals Metalorganic chemical vapor deposition of InN quantum dots and nanostructures

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Caroline E. Reilly ◽  
Stacia Keller ◽  
Shuji Nakamura ◽  
Steven P. DenBaars
Keyword(s):  
Quantum Dots ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Near Infrared ◽  
Optoelectronic Devices ◽  
Chemical Vapor ◽  
Electromagnetic Spectrum ◽  
Material System ◽  
Metalorganic Chemical

AbstractUsing one material system from the near infrared into the ultraviolet is an attractive goal, and may be achieved with (In,Al,Ga)N. This III-N material system, famous for enabling blue and white solid-state lighting, has been pushing towards longer wavelengths in more recent years. With a bandgap of about 0.7 eV, InN can emit light in the near infrared, potentially overlapping with the part of the electromagnetic spectrum currently dominated by III-As and III-P technology. As has been the case in these other III–V material systems, nanostructures such as quantum dots and quantum dashes provide additional benefits towards optoelectronic devices. In the case of InN, these nanostructures have been in the development stage for some time, with more recent developments allowing for InN quantum dots and dashes to be incorporated into larger device structures. This review will detail the current state of metalorganic chemical vapor deposition of InN nanostructures, focusing on how precursor choices, crystallographic orientation, and other growth parameters affect the deposition. The optical properties of InN nanostructures will also be assessed, with an eye towards the fabrication of optoelectronic devices such as light-emitting diodes, laser diodes, and photodetectors.

Study of multiple-stacking growth of 1.55μm InAs columnar quantum dots with modulated tensile-strained InGaAsP barrier layers

2012 ◽  
Vol 340 (1) ◽  
pp. 87-91
Author(s):  
Shigekazu Okumura ◽  
Nami Yasuoka ◽  
Kenichi Kawaguchi ◽  
Yu Tanaka ◽  
Mitsuru Ekawa
Keyword(s):  
Quantum Dots ◽  
Barrier Layers

Novel Stm Probe Assisted Site-Control of Quantum Dots With Nanometer Precision

1999 ◽  
Vol 583 ◽  
Author(s):  
Hitoshi Nakamura ◽  
Shigeru Kohmoto ◽  
Tomonori Ishikawa ◽  
Kiyoshi Asakawa
Keyword(s):  
Quantum Dots ◽  
Gaas Surface ◽  
Control Technique ◽  
Formation Processes ◽  
Chamber System ◽  
Wetting Layer ◽  
Layer Formation ◽  
System A ◽  
Tungsten Tip ◽  
Site Control

AbstractWe propose a novel site-control technique for strained quantum dots (QDs) based on nano-lithography using an STM integrated into a UHV STM/MBE multi-chamber system. A nano-scale deposit was formed on a GaAs surface by applying voltage between the GaAs surface and the tungsten tip of the STM. Since the deposit acted as a nano-mask, the subsequent GaAs growth formed a nano-hole just above the deposit. Subsequent InAs supply produced a QD on the hole site, and no QD was observed in any undesirable regions. We also observed the QD formation processes involved in the technique, based on step-by-step STM observations of the QD formation process. The observation directly revealed an InAs wetting layer formation with 1-ML thickness on the GaAs terraces followed by the QD formation in the Stranski-Krastanow growth mode.

scholarly journals Simulation of Quantum-Dot Structures in Si/SiO2

VLSI Design ◽  
1998 ◽  
Vol 6 (1-4) ◽  
pp. 335-339 ◽  
Author(s):  
Minhan Chen ◽  
Wolfgang Porod
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Boundary Conditions ◽  
Numerical Simulations ◽  
Material System ◽  
Exposed Surface ◽  
Confining Potential ◽  
The Poisson Equation ◽  
Charge Model ◽  
Electron Quantum

We present numerical simulations for the design of gated few-electron quantum dot structures in the Si/SiO2 material system. Because of the vicinity of the quantum dots to the exposed surface, we take special care in treating the boundary conditions at the oxide/vacuum interfaces. In our simulations, the confining potential is obtained from the Poisson equation with a Thomas-Fermi charge model. We find that the dot occupancy can be effectively controlled in the few-electron regime.

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