scholarly journals Hydrostatic Pressure and Built-In Electric Field Effects on the Donor Impurity States in Cylindrical Wurtzite GaN/AlxGa1−xN Quantum Rings

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Guangxin Wang ◽  
Xiuzhi Duan ◽  
Rui Zhou
Keyword(s):  
Hydrostatic Pressure ◽  
Binding Energy ◽  
Electric Field ◽  
Growth Direction ◽  
Quantum Ring ◽  
Hydrogenic Impurity ◽  
Mass Approximation ◽  
Donor Binding Energy ◽  
Radial Thickness ◽  
Physical Reasons

Within the framework of the effective mass approximation, the ground-state binding energy of a hydrogenic impurity is investigated in cylindrical wurtzite GaN/AlxGa1-xNstrained quantum ring (QR) by means of a variational approach, considering the influence of the applied hydrostatic pressure along the QR growth direction and the strong built-in electric field (BEF) due to the piezoelectricity and spontaneous polarization. Numerical results show that the donor binding energy for a central impurity increases inchmeal firstly as the QR radial thickness(ΔR)decreases gradually and then begins to drop quickly. In addition, the donor binding energy is an increasing (a decreasing) function of the inner radius (height). It is also found that the donor binding energy increases almost linearly with the increment of the applied hydrostatic pressure. Moreover, we also found that impurity positions have an important influence on the donor binding energy. The physical reasons have been analyzed in detail.

Influence of Al Composition on Donor Impurity States in Self-Formed GaAs-AlxGa1-xAs Quantum Rings

2013 ◽  
Vol 380-384 ◽  
pp. 4284-4289
Author(s):  
Guang Xin Wang ◽  
Xiu Zhi Duan
Keyword(s):  
Binding Energy ◽  
Electric Field ◽  
Growth Direction ◽  
Uniform Electric Field ◽  
Donor Impurity ◽  
Impurity States ◽  
Quantum Rings ◽  
Mass Approximation ◽  
Donor Binding Energy ◽  
Special Value

Based on the the effective mass approximation and variational approach, the donor impurity states confined in self-formed GaAs/AlxGa1-xAs quantum rings (QRs) are investigated theoretically. A uniform electric field is applied along the growth direction of the QR. The different effective masses in the different regions of the GaAs/AlxGa1-xAs QR are taken into consideration. Numerical results show that the binding energy of a donor impurity increases gradually, reaches a maximum value, and then decreases quickly to the special value as the QR height decreases. Given a fixed QR size, the binding energy increases for the impurity located at the center of the QR when the Al composition increases. In addition, it can also be found that when the applied electric field strength increases, the donor binding energy increases for impurities localized at the negative z axis of the QR; however, the donor binding energy decreases slightly for impurities located at the center and positive z axis of the QR.

HYDROGENIC IMPURITY STATES IN WURTZITE ZnO/MgZnO QUANTUM DOT

2010 ◽  
Vol 24 (28) ◽  
pp. 2793-2801
Author(s):  
ZAIPING ZENG ◽  
SHUYI WEI ◽  
JINGBO WEI
Keyword(s):  
Binding Energy ◽  
Quantum Dot ◽  
Electric Field ◽  
Ground State ◽  
Asymmetric Distribution ◽  
Electric Field Effect ◽  
Hydrogenic Impurity ◽  
Mass Approximation ◽  
Donor Binding Energy ◽  
The Right

Based on the effective-mass approximation, considering the built-in electric field effect due to the spontaneous and piezoelectric polarizations, the ground-state donor binding energy of a hygrogenic impurity in a cylindrical wurzite (WZ) ZnO / MgZnO strained quantum dot (QD) is investigated variationally. Numerical results show that the ground-state donor binding energy is highly dependent on the Mg composition, the impurity positions and the QD size. The built-in electric field also induces an asymmetric distribution of the ground-state donor binding energy with respect to the center of the QD. In particular, it is found that the ground-state donor binding energy is insensible to the dot height when the impurity is located at the right boundary of the WZ ZnO / MgZnO strained QD if the dot height is large.

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.

THE EFFECTS OF HYDROSTATIC PRESSURE AND APPLIED ELECTRIC FIELD ON SHALLOW DONOR IMPURITIES IN GaAs/GaAlAs GRADED QUANTUM WELL

2005 ◽  
Vol 12 (02) ◽  
pp. 155-159 ◽  
Author(s):  
E. KASAPOGLU ◽  
H. SARI ◽  
I. SÖKMEN
Keyword(s):  
Hydrostatic Pressure ◽  
Binding Energy ◽  
Electric Field ◽  
Quantum Well ◽  
Quantum Confinement ◽  
Variational Approach ◽  
Shallow Donor ◽  
Impurity Position ◽  
Donor Binding Energy ◽  
Electric Field Direction

Using a variational approach, we have investigated the effects of the hydrostatic pressure, the well dimension, impurity position and electric field direction on the binding energy of shallow donor impurities in GaAs/GaAlAs graded quantum well (GQW). We have found that the changes in donor binding energy in GQW strongly depend not only on the quantum confinement, but also on the hydrostatic pressure, on the direction of the electric field and on the impurity position.

THE EFFECTS OF QUANTUM CONFINEMENT ON THE BINDING ENERGY OF HYDROGENIC IMPURITIES IN A SPHERICAL QUANTUM DOT

2006 ◽  
Vol 20 (18) ◽  
pp. 1127-1134 ◽  
Author(s):  
A. JOHN PETER
Keyword(s):  
Binding Energy ◽  
Quantum Dot ◽  
Shallow Donor ◽  
Donor Impurity ◽  
Hydrogenic Impurity ◽  
Spherical Quantum Dot ◽  
Impurity Position ◽  
Mass Approximation ◽  
Donor Binding Energy ◽  
Parabolic Confinement

The binding energy of a shallow hydrogenic impurity of a spherical quantum dot confined by harmonic oscillator-like and by rectangular well-like potentials, using a variational procedure within the effective mass approximation, has been determined. The calculations of the binding energy of the donor impurity as a function of the system geometry, and the donor impurity position have been investigated. The binding energy of shallow donor impurity depends not only on the quantum confinements but also on the impurity position. Our results reveal that (i) the donor binding energy decreases as the dot size increases irrespective of the impurity position, and (ii) the binding energy values of rectangular confinement are larger than the values of parabolic confinement and (iii) the rectangular confinement is better than the parabolic confinement in a spherical quantum dot.

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