Photoluminescence Investigation of the Effects of Barrier Thickness and Monolayer Coverage on Properties of Bilayer InAs/GaAs Quantum Dots

2008 ◽  
Vol 3 (3) ◽  
pp. 277-280 ◽  
Author(s):  
S. Chakrabarti ◽  
N. Halder ◽  
S. Sengupta ◽  
Jayant Charthad ◽  
Sandip Ghosh ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Barrier Thickness ◽  
Monolayer Coverage

Tuning of near infrared excitonic emission from InAs quantum dots by controlling the sub-monolayer coverage

2019 ◽  
Vol 210 ◽  
pp. 311-321 ◽  
Author(s):  
S. Mukherjee ◽  
A. Pradhan ◽  
S. Mukherjee ◽  
T. Maitra ◽  
S. Sengupta ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Near Infrared ◽  
Inas Quantum Dots ◽  
Excitonic Emission ◽  
Monolayer Coverage

scholarly journals Barrier Thickness and Hydrostatic Pressure Effects on Hydrogenic Impurity States in Wurtzite GaN/AlxGa1−xN Strained Quantum Dots

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Guangxin Wang ◽  
Xiuzhi Duan ◽  
Wei Chen
Keyword(s):  
Quantum Dots ◽  
Hydrostatic Pressure ◽  
Binding Energy ◽  
Effective Mass ◽  
Dielectric Constants ◽  
Pressure Effects ◽  
Physical Parameters ◽  
Barrier Thickness ◽  
Hydrogenic Impurity ◽  
Donor Binding Energy

Within the framework of the effective mass approximation, barrier thickness and hydrostatic pressure effects on the ground-state binding energy of hydrogenic impurity are investigated in wurtzite (WZ) GaN/AlxGa1−xN strained quantum dots (QDs) by means of a variational approach. The hydrostatic pressure dependence of physical parameters such as electron effective mass, energy band gaps, lattice constants, and dielectric constants is considered in the calculations. Numerical results show that the donor binding energy for any impurity position increases when the hydrostatic pressure increases. The donor binding energy for the impurity located at the central of the QD increases firstly and then begins to drop quickly with the decrease of QD radius (height) in strong built-in electric fields. Moreover, the influence of barrier thickness along the QD growth direction and Al concentration on donor binding energy is also investigated. In addition, we also found that impurity positions have great influence on the donor binding energy.

Comparison of single-layer and bilayer InAs/GaAs quantum dots with a higher InAs coverage

2010 ◽  
Vol 18 (3) ◽  
Author(s):  
S. Sengupta ◽  
S.Y. Shah ◽  
N. Halder ◽  
S. Chakrabarti
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Emission Line ◽  
Size Distribution ◽  
Single Layer ◽  
Quantum Dot Lasers ◽  
Narrow Linewidth ◽  
Inas Quantum Dots ◽  
Monolayer Coverage ◽  
Narrow Emission

AbstractEpitaxially grown self-assembled InAs quantum dots (QDs) have found applications in optoelectronics. Efforts are being made to obtain efficient quantum-dot lasers operating at longer telecommunication wavelengths, specifically 1.3 μm and 1.55 μm. This requires narrow emission linewidth from the quantum dots at these wavelengths. In InAs/GaAs single layer quantum dot (SQD) structure, higher InAs monolayer coverage for the QDs gives rise to larger dots emitting at longer wavelengths but results in inhomogeneous dot-size distribution. The bilayer quantum dot (BQD) can be used as an alternative to SQDs, which can emit at longer wavelengths (1.229 μm at 8 K) with significantly narrow linewidth (∼16.7 meV). Here, we compare the properties of single layer and bilayer quantum dots grown with higher InAs monolayer coverage. In the BQD structure, only the top QD layer is covered with increased (3.2 ML) InAs monolayer coverage. The emission line width of our BQD sample is found to be insensitive towards post growth treatments.

DIMENSIONAL TRANSITIONS OF DENSITY OF STATES AND HEAT CAPACITY IN SPHERICAL QUANTUM DOTS

2008 ◽  
Vol 22 (15) ◽  
pp. 2373-2382
Author(s):  
SEUNG JOO LEE ◽  
HEE CHANG JEON ◽  
TAE WON KANG ◽  
SATOFUMI SOUMA
Keyword(s):  
Quantum Dots ◽  
Heat Capacity ◽  
Density Of States ◽  
Three Dimensional ◽  
Potential Barrier Height ◽  
Low Density ◽  
Barrier Thickness ◽  
Spherical Quantum Dot ◽  
Thin Barrier ◽  
Density Regime

We evaluate analytically and numerically the density of states (DOS) and the heat capacity in a spherical quantum dot formed by a spherical thin barrier. The control of the spherical barrier thickness or the potential barrier height is found to cause the dimensional transition from the three-dimensional (3D) behavior to the quasi-zero dimensional (Q0D) behavior in the DOS and the heat capacity. When the barrier is thick enough, the DOS shows the Q0D-like behavior but when the barrier is thin enough to allow electrons to tunnel through it, the temperature dependence of the heat capacity exhibits quite a distinct behavior depending on the electron density. Explicit numerical plots are given in the low density regime.

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