MBE Growth and Characterization of Composite InAlAs/In(Ga)As Vertically Aligned Quantum Dots

1999 ◽  
Vol 571 ◽  
Author(s):  
A. R. Kovsh ◽  
A. E. Zhukov ◽  
A.Yu. Egorov ◽  
N. N. Maleev ◽  
S. S. Mikhrin ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Continuous Wave ◽  
Areal Density ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Spontaneous Transformation ◽  
Continuous Wave Output Power ◽  
Transmission Electron ◽  
Internal Loss ◽  
Photoluminescence Studies

ABSTRACTIn the present work we study the effect of vertical alignment in the quantum dot array formed by successive deposition of several rows of InAlAs and InGaAs quantum dots separated by thin AIGaAs spacer layers. Transmission electron microscopy and photoluminescence studies revealed that the InAlAs QDs characterized by high areal density force InGaAs to be transformed into the denser array as compared to the case of spontaneous transformation. Using denser array of composite quantum dots in the active region of a diode laser leads to the increase in modal gain, decrease in internal loss, and decrease in the threshold current density for short cavity diodes. Room temperature continuous wave output power as high as 3.3 W at 0.87 µm is achieved.

InAs Quantum Dots in AlAs/GaAs Short Period Superlattices: Structure, Optical Characteristics and Laser Diodes

2001 ◽  
Vol 707 ◽  
Author(s):  
Vadim Tokranov ◽  
M. Yakimov ◽  
A. Katsnelson ◽  
K. Dovidenko ◽  
R. Todt ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Room Temperature ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Inas Quantum Dots ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices ◽  
Emitting Lasers ◽  
Cladding Layers

ABSTRACTThe influence of two monolayer - thick AlAs under- and overlayers on the formation and properties of self-assembled InAs quantum dots (QDs) has been studied using transmission electron microscopy (TEM) and photoluminescence (PL). Single sheets of InAs QDs were grown inside a 2ML/8ML AlAs/GaAs short-period superlattice with various combinations of under- and overlayers. It was found that 2.4ML InAs QDs with GaAs underlayer and 2ML AlAs overlayer exhibited the lowest QD surface density of 4.2x1010 cm-2 and the largest QD lateral size of about 19 nm as compared to the other combinations of cladding layers. This InAs QD ensemble has also shown the highest room temperature PL intensity with a peak at 1210 nm and the narrowest linewidth, 34 meV. Fabricated edge-emitting lasers using triple layers of InAs QDs with AlAs overlayer demonstrated 120 A/cm2 threshold current density and 1230 nm emission wavelength at room temperature. Excited state QD lasers have shown high thermal stability of threshold current up to 130°C.

InAs quantum dots in AlAs/GaAs short period superlattices: structure, optical characteristics and laser diodes

2001 ◽  
Vol 692 ◽  
Author(s):  
Vadim Tokranov ◽  
M. Yakimov ◽  
A. Katsnelson ◽  
K. Dovidenko ◽  
R. Todt ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Room Temperature ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Inas Quantum Dots ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices ◽  
Emitting Lasers ◽  
Cladding Layers

AbstractThe influence of two monolayer - thick AlAs under- and overlayers on the formation and properties of self-assembled InAs quantum dots (QDs) has been studied using transmission electron microscopy (TEM) and photoluminescence (PL). Single sheets of InAs QDs were grown inside a 2ML/8ML AlAs/GaAs short-period superlattice with various combinations of under- and overlayers. It was found that 2.4ML InAs QDs with GaAs underlayer and 2ML AlAs overlayer exhibited the lowest QD surface density of 4.2×1010 cm-2 and the largest QD lateral size of about 19 nm as compared to the other combinations of cladding layers. This InAs QD ensemble has also shown the highest room temperature PL intensity with a peak at 1210 nm and the narrowest linewidth, 34 meV. Fabricated edge-emitting lasers using triple layers of InAs QDs with AlAs overlayer demonstrated 120 A/cm2 threshold current density and 1230 nm emission wavelength at room temperature. Excited state QD lasers have shown high thermal stability of threshold current up to 130°C.

scholarly journals In Situ Observation of Electron-Beam-Induced Formation of Nano-Structures in PbTe

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 163
Author(s):  
Iryna Zelenina ◽  
Igor Veremchuk ◽  
Yuri Grin ◽  
Paul Simon
Keyword(s):  
Electron Beam ◽  
Gas Phase ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Atomic Scale ◽  
In Situ Observation ◽  
Nano Structures ◽  
Transmission Electron ◽  
Initial Crystal

Nano-scaled thermoelectric materials attract significant interest due to their improved physical properties as compared to bulk materials. Well-shaped nanoparticles such as nano-bars and nano-cubes were observed in the known thermoelectric material PbTe. Their extended two-dimensional nano-layer arrangements form directly in situ through electron-beam treatment in the transmission electron microscope. The experiments show the atomistic depletion mechanism of the initial crystal and the recrystallization of PbTe nanoparticles out of the microparticles due to the local atomic-scale transport via the gas phase beyond a threshold current density of the beam.

scholarly journals InAs/GaAs Quantum Dot Microlasers Formed on Silicon Using Monolithic and Hybrid Integration Methods

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2315
Author(s):  
Alexey E. Zhukov ◽  
Natalia V. Kryzhanovskaya ◽  
Eduard I. Moiseev ◽  
Anna S. Dragunova ◽  
Mingchu Tang ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Current Density ◽  
Elevated Temperatures ◽  
Continuous Wave ◽  
Electrical Contact ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Constant Current ◽  
Surface Protection ◽  
Microdisk Lasers

An InAs/InGaAs quantum dot laser with a heterostructure epitaxially grown on a silicon substrate was used to fabricate injection microdisk lasers of different diameters (15–31 µm). A post-growth process includes photolithography and deep dry etching. No surface protection/passivation is applied. The microlasers are capable of operating heatsink-free in a continuous-wave regime at room and elevated temperatures. A record-low threshold current density of 0.36 kA/cm2 was achieved in 31 µm diameter microdisks operating uncooled. In microlasers with a diameter of 15 µm, the minimum threshold current density was found to be 0.68 kA/cm2. Thermal resistance of microdisk lasers monolithically grown on silicon agrees well with that of microdisks on GaAs substrates. The ageing test performed for microdisk lasers on silicon during 1000 h at a constant current revealed that the output power dropped by only ~9%. A preliminary estimate of the lifetime for quantum-dot (QD) microlasers on silicon (defined by a double drop of the power) is 83,000 h. Quantum dot microdisk lasers made of a heterostructure grown on GaAs were transferred onto a silicon wafer using indium bonding. Microlasers have a joint electrical contact over a residual n+ GaAs substrate, whereas their individual addressing is achieved by placing them down on a p-contact to separate contact pads. These microdisks hybridly integrated to silicon laser at room temperature in a continuous-wave mode. No effect of non-native substrate on device characteristics was found.

PERFORMANCE ENHANCEMENT OF InGaN-BASED LASER DIODES USING A STEP-GRADED AlxGa1-xN ELECTRON BLOCKING LAYER

2011 ◽  
Vol 20 (03) ◽  
pp. 515-520
Author(s):  
Y. ZHANG ◽  
J.-P. LIU ◽  
T.-T. KAO ◽  
S. KIM ◽  
Y.-C. LEE ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Performance Enhancement ◽  
Laser Diodes ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Device Performance ◽  
Blocking Layer ◽  
Electron Blocking Layer ◽  
Electron Accumulation ◽  
Continuous Wave Operation

A step-graded Al x Ga 1- x N electron blocking layer (EBL) is introduced to the InGaN -based edge-emitting blue-violet laser diode (LD) structure to suppress the undesired built-in interface polarization charges. When compared to a conventional abrupt Al 0.18 Ga 0.82 N EBL design, the step-graded Al x Ga 1- x N EBL design may help reduce the electron accumulation at the edge of the active region and hence improve the quantum efficiency in LD operation. The effects of the step-graded Al x Ga 1- x N EBL on the fabricated device performance are also investigated. LDs with the step-graded Al x Ga 1- x N EBL demonstrated significantly reduced threshold current density and increased slope efficiency under the continuous-wave operation.

InP Self Assembled Quantum Dot Lasers Grown on GaAs Substrates by Metalorganic Chemical Vapor Deposition

2001 ◽  
Vol 692 ◽  
Author(s):  
R. D. Dupuis ◽  
J. H. Ryou ◽  
R. D. Heller ◽  
G. Walter ◽  
D. A. Kellogg ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Chemical Vapor ◽  
Active Regions ◽  
Threshold Current ◽  
Double Quantum ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Inp Quantum Dots

AbstractWe describe the operation of lasers having active regions composed of InP selfassembled quantum dots embedded in In0.5Al0.3Ga0.2P grown on GaAs (100) substrates by MOCVD. InP quantum dots grown on In0.5Al0.3Ga0.2P have a high density on the order of about 1–2×10 cm−2 with a dominant size of about 10–15 nm for 7.5 ML growth.[1] These In0.5Al0.3Ga0.2P/InP quantum dots have previously been characterized by atomic-force microscopy, high-resolution transmission electron microscopy, and photoluminescence.[2] We report here the 300K operation of optically pumped red-emitting quantum dots using both double quantum-dot active regions and quantum-dot coupled with InGaP quantum-well active regions. Optically and electrically pumped 300K lasers have been obtained using this active region design; these lasers show improved operation compared to the lasers having QD-based active regions with threshold current densities as low as Jth ∼ 0.5 KA/cm2.

scholarly journals Лазерная генерация перенесенных на кремний инжекционных микродисков с квантовыми точками InAs/InGaAs/GaAs

2020 ◽  
Vol 46 (16) ◽  
pp. 3
Author(s):  
А.Е. Жуков ◽  
Э.И. Моисеев ◽  
А.М. Надточий ◽  
А.C. Драгунова ◽  
Н.В. Крыжановская ◽  
...  
Keyword(s):  
Gaas Substrate ◽  
Continuous Wave ◽  
Electrical Contact ◽  
Spectral Characteristics ◽  
Threshold Current ◽  
Wave Mode ◽  
Threshold Current Density ◽  
Lasing Wavelength ◽  
External Cooling ◽  
Continuous Wave Mode

AlGaAs/GaAs microdisk lasers with InAs/InGaAs quantum dots region were transferred onto a silicon wafer using indium bonding. Microlasers have a joint electrical contact put over a residual n+ GaAs substrate, whereas their individual addressing is achieved by placing them p-contact down to separate contact pads. No effect of non-native substrate on electrical resistance, threshold current, thermal resistance, and spectral characteristics was revealed. Microdisks lase in continuous-wave mode without external cooling with the threshold current density of 0.7 kA/cm2. Lasing wavelength remains stable (<0.1 nm/mA) against injection current increment.

Investigation into the InAs/GaAs quantum dot material epitaxially grown on silicon for O band lasers

2022 ◽  
Vol 43 (1) ◽  
pp. 012301
Author(s):  
Tianyi Tang ◽  
Tian Yu ◽  
Guanqing Yang ◽  
Jiaqian Sun ◽  
Wenkang Zhan ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Quantum Dot ◽  
Large Scale ◽  
Continuous Wave ◽  
Low Cost ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Silicon Substrates ◽  
Growth Method ◽  
Gaas Quantum Dot

Abstract InAs/GaAs quantum dot (QD) lasers were grown on silicon substrates using a thin Ge buffer and three-step growth method in the molecular beam epitaxy (MBE) system. In addition, strained superlattices were used to prevent threading dislocations from propagating to the active region of the laser. The as-grown material quality was characterized by the transmission electron microscope, scanning electron microscope, X-ray diffraction, atomic force microscope, and photoluminescence spectroscopy. The results show that a high-quality GaAs buffer with few dislocations was obtained by the growth scheme we developed. A broad-area edge-emitting laser was also fabricated. The O-band laser exhibited a threshold current density of 540 A/cm2 at room temperature under continuous wave conditions. This work demonstrates the potential of large-scale and low-cost manufacturing of the O-band InAs/GaAs quantum dot lasers on silicon substrates.

Shape Engineered InAs Quantum Dots with Stabilized Electronic Properties

2002 ◽  
Vol 737 ◽  
Author(s):  
V. Tokranov ◽  
M. Yakimov ◽  
A. Katsnelson ◽  
K. Dovidenko ◽  
M. Lamberti ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Room Temperature ◽  
State Energy ◽  
Growth Parameters ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Temperature Threshold ◽  
Inas Quantum Dots ◽  
Subsequent Heating ◽  
Heating Up

ABSTRACTWe have studied the influence of overgrowth procedure and a few monolayer-thick AlAs overlayer on the properties of self-assembled InAs quantum dots (QDs) using scanning electron microscopy (SEM) and photoluminescence (PL). PL spectroscopy was used to optimize optical properties of the QDs by shape engineering (QD truncation) through adjustment of the thickness of overlayers and temperature of the subsequent heating. QDs with 6 nm - thick overlayer with subsequent heating up to 560°C was found to have the highest PL intensity at room temperature and the lowest FWHM, 29 meV. Ground state energy of the truncated QDs is very stable against variations of growth parameters. 1.23 μm edge-emitting laser of triple-layer QD structure demonstrated room temperature threshold current density, 74 A/cm2.

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