Simultaneous effects of an on-center hydrogenic impurity and band edge non-parabolicity on intersubband optical absorption coefficients and refractive index changes of a typical GaAs/AlxGa1-xAs spherical quantum dot a...Simultaneous effects of an on-center hydrogenic impurity and band edge non-parabolicity on intersubband optical absorption coefficients and refractive index changes of a typical GaAs/AlxGa1-xAs spherical quantum dot are theoretically investigated, using the Luttinger-Kohn effective mass equation. So, electronic structure and optical properties of the system are studied by means of the matrix diagonalization technique and compact density matrix approach, respectively. Finally, effects of an impurity, band edge non-parabolicity, incident light intensity and the dot size on the linear, the third-order nonlinear and the total optical absorption coemcients and refractive index changes are investigated. Our results indicate that, the magnitudes of these optical quantities increase and their peaks shift to higher energies as the influences of the impurity and the band edge non-parabolicity are considered. Moreover, incident light intensity and the dot size have considerable effects on the optical absorption coefficients and refractive index changes.展开更多
The shallow hydrogenic donor impurity states in square, V-shaped, and parabolic quantum wells are studied in the framework of effective-mass envelope-function theory using the plane wave basis. The first four impurity...The shallow hydrogenic donor impurity states in square, V-shaped, and parabolic quantum wells are studied in the framework of effective-mass envelope-function theory using the plane wave basis. The first four impurity energy levels and binding energy of the ground state are more easily calculated than with the variation method. The calculation results indicate that impurity energy levels decrease with the increase of the well width and decrease quickly when the well width is small. The binding energy of the ground state increases until it reaches a maximum value, and then decreases as the well width increases. The results are meaningful and can be widely applied in the design of various optoelectronie devices.展开更多
The ground-state and lowest excited-state binding energies of a hydrogenic impurity in GaAs parabolic quantum-well wires （Q WWs） subjected to external electric and magnetic fields are investigated using the finite-d...The ground-state and lowest excited-state binding energies of a hydrogenic impurity in GaAs parabolic quantum-well wires （Q WWs） subjected to external electric and magnetic fields are investigated using the finite-difference method within the quasi-one-dimensional effective potential model. We define an effective radius Pen of a cylindrical QWW, which can describe the strength of the lateral confinement. For the ground state, the position of the largest probability density of electron in x-y plane is located at a point, while for the lowest excited state, is located on a circularity whose radius is Pen. The point and circularity are pushed along the left haft of the center axis of the quantum-well wire by the electric field dire ted along the right half. When an impurity is located at the point or within the circularity, the ground-state or lowest excited-state binding energies are the largest; when the impurity is apart from the point or circularity, the ground-state or lowest excited-state binding energies start to decrease.展开更多
Simultaneous effects of conduction band non-parabolicity and hydrostatic pressure on the binding energies of 1S, 2S, and 2P states along with diamagnetic susceptibility of an on-center hydrogenic impurity confined in ...Simultaneous effects of conduction band non-parabolicity and hydrostatic pressure on the binding energies of 1S, 2S, and 2P states along with diamagnetic susceptibility of an on-center hydrogenic impurity confined in typical GaAs/Alx- Ga1-x As spherical quantum dots are theoretically investigated using the matrix diagonalization method. In this regard, the effect of band non-parabolieity has been performed using the Luttinger-Kohn effective mass equation. The binding energies and the diamagnetic susceptibility of the hydrogenic impurity are computed as a function of the dot radius and different values of the pressure in the presence of conduction band non-parabolicity effect. The results we arrived at are as follows： the incorporation of the band edge non-parabolicity increases the binding energies and decreases the absolute value of the diamagnetic susceptibility for a given pressure and radius; the binding energies increase and the magnitude of the diamagnetic susceptibility reduces with increasing pressure.展开更多
Both the LUNA（Laboratory for Underground Nuclear Astrophysics）collaboration in Europe and the JUNA（Jinping Underground Laboratory for Nuclear Astrophysics）collaboration in China are planning to study the key react...Both the LUNA（Laboratory for Underground Nuclear Astrophysics）collaboration in Europe and the JUNA（Jinping Underground Laboratory for Nuclear Astrophysics）collaboration in China are planning to study the key reactions during the stellar helium burning at or close to their stellar energies in deep underground laboratories[1-3].展开更多
Mo-Ta合金作为一种有高熔点、抗辐照等特点的材料,被视为聚变工程中制造第一壁的潜在材料。目前有关Mo-Ta合金与H杂质相互作用的研究还不完善,本文研究了H杂质在体心立方Mo53Ta_(1)合金中间隙位置的成键机制。通过基于密度泛函的第一性...Mo-Ta合金作为一种有高熔点、抗辐照等特点的材料,被视为聚变工程中制造第一壁的潜在材料。目前有关Mo-Ta合金与H杂质相互作用的研究还不完善,本文研究了H杂质在体心立方Mo53Ta_(1)合金中间隙位置的成键机制。通过基于密度泛函的第一性原理方法,通过Material Studio的CASTEP(Cambridge Serial Total Energy Package)模块计算了Mo53Ta_(1)-H体系的溶解能,态密度与布居数。溶解能计算结果表明:H原子在Mo-Ta合金中更倾向于存在与四面体间隙位置;通过分波态密度与布居数,分析了H、Mo、Ta之间不同电子轨道间电子转移情况与不同原子间的成键情况。得出Mo、Ta间为金属键,H与Ta和Mo之间存在共价作用,且H与Ta之间的共价作用更强。展开更多
The dependence of the ground-state properties of weak-coupling bound magnetopolarons in quantum rods (QRs) with hydrogenic impurity on magnetic field and temperature is studied by means of the Lee-Low-Pines (LLP) tran...The dependence of the ground-state properties of weak-coupling bound magnetopolarons in quantum rods (QRs) with hydrogenic impurity on magnetic field and temperature is studied by means of the Lee-Low-Pines (LLP) transformation method and Huybrechts linear combination operator method. The expression for the ground-state energy of the magnetopolaron is derived. Results of the numerical calculations show that the ground-state energy of weak-coupling bound magnetopolarons in QRs with hydrogenic impurity increases with increasing the cyclotron frequency of the magnetic field, the confinement strength of QRs and the temperature, but decreases with increasing the electron-phonon coupling strength and the dielectric constant ratio. The stability of the ground state of magnetopolarons is closely related to the aspect ratio e′of the QR. The ground state of magnetopolarons is the most stable at e′=1. The stability of the ground state of magnetopolarons can remarkably decrease when the value of the aspect ratio increases or decreases from 1.展开更多
文摘Simultaneous effects of an on-center hydrogenic impurity and band edge non-parabolicity on intersubband optical absorption coefficients and refractive index changes of a typical GaAs/AlxGa1-xAs spherical quantum dot are theoretically investigated, using the Luttinger-Kohn effective mass equation. So, electronic structure and optical properties of the system are studied by means of the matrix diagonalization technique and compact density matrix approach, respectively. Finally, effects of an impurity, band edge non-parabolicity, incident light intensity and the dot size on the linear, the third-order nonlinear and the total optical absorption coemcients and refractive index changes are investigated. Our results indicate that, the magnitudes of these optical quantities increase and their peaks shift to higher energies as the influences of the impurity and the band edge non-parabolicity are considered. Moreover, incident light intensity and the dot size have considerable effects on the optical absorption coefficients and refractive index changes.
基金Supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (PRC)Foundation of Qufu Normal University under Grant No. XJ0622
文摘The shallow hydrogenic donor impurity states in square, V-shaped, and parabolic quantum wells are studied in the framework of effective-mass envelope-function theory using the plane wave basis. The first four impurity energy levels and binding energy of the ground state are more easily calculated than with the variation method. The calculation results indicate that impurity energy levels decrease with the increase of the well width and decrease quickly when the well width is small. The binding energy of the ground state increases until it reaches a maximum value, and then decreases as the well width increases. The results are meaningful and can be widely applied in the design of various optoelectronie devices.
文摘The ground-state and lowest excited-state binding energies of a hydrogenic impurity in GaAs parabolic quantum-well wires （Q WWs） subjected to external electric and magnetic fields are investigated using the finite-difference method within the quasi-one-dimensional effective potential model. We define an effective radius Pen of a cylindrical QWW, which can describe the strength of the lateral confinement. For the ground state, the position of the largest probability density of electron in x-y plane is located at a point, while for the lowest excited state, is located on a circularity whose radius is Pen. The point and circularity are pushed along the left haft of the center axis of the quantum-well wire by the electric field dire ted along the right half. When an impurity is located at the point or within the circularity, the ground-state or lowest excited-state binding energies are the largest; when the impurity is apart from the point or circularity, the ground-state or lowest excited-state binding energies start to decrease.
文摘Simultaneous effects of conduction band non-parabolicity and hydrostatic pressure on the binding energies of 1S, 2S, and 2P states along with diamagnetic susceptibility of an on-center hydrogenic impurity confined in typical GaAs/Alx- Ga1-x As spherical quantum dots are theoretically investigated using the matrix diagonalization method. In this regard, the effect of band non-parabolieity has been performed using the Luttinger-Kohn effective mass equation. The binding energies and the diamagnetic susceptibility of the hydrogenic impurity are computed as a function of the dot radius and different values of the pressure in the presence of conduction band non-parabolicity effect. The results we arrived at are as follows： the incorporation of the band edge non-parabolicity increases the binding energies and decreases the absolute value of the diamagnetic susceptibility for a given pressure and radius; the binding energies increase and the magnitude of the diamagnetic susceptibility reduces with increasing pressure.
基金the equipment research and development project of Chinese Academy of Sciences(Grant No.28Y531040)support from the National Natural Science Foundation of China(Grants Nos.11021504,11321064,11475228,and 11490564)+2 种基金the National Key Basic Research Program of China(Grants No.2016YFA0400501)the 100 Talents Program of the Chinese Academy of Sciencessupport from the National Science Foundation for Young Scientists of China(Grant No.11405228)
文摘Both the LUNA（Laboratory for Underground Nuclear Astrophysics）collaboration in Europe and the JUNA（Jinping Underground Laboratory for Nuclear Astrophysics）collaboration in China are planning to study the key reactions during the stellar helium burning at or close to their stellar energies in deep underground laboratories[1-3].
文摘Mo-Ta合金作为一种有高熔点、抗辐照等特点的材料,被视为聚变工程中制造第一壁的潜在材料。目前有关Mo-Ta合金与H杂质相互作用的研究还不完善,本文研究了H杂质在体心立方Mo53Ta_(1)合金中间隙位置的成键机制。通过基于密度泛函的第一性原理方法,通过Material Studio的CASTEP(Cambridge Serial Total Energy Package)模块计算了Mo53Ta_(1)-H体系的溶解能,态密度与布居数。溶解能计算结果表明:H原子在Mo-Ta合金中更倾向于存在与四面体间隙位置;通过分波态密度与布居数,分析了H、Mo、Ta之间不同电子轨道间电子转移情况与不同原子间的成键情况。得出Mo、Ta间为金属键,H与Ta和Mo之间存在共价作用,且H与Ta之间的共价作用更强。
基金supported by the Items of Institution of Higher Education Scientific Research of Inner Mongolia of China (No.NJ101116)
文摘The dependence of the ground-state properties of weak-coupling bound magnetopolarons in quantum rods (QRs) with hydrogenic impurity on magnetic field and temperature is studied by means of the Lee-Low-Pines (LLP) transformation method and Huybrechts linear combination operator method. The expression for the ground-state energy of the magnetopolaron is derived. Results of the numerical calculations show that the ground-state energy of weak-coupling bound magnetopolarons in QRs with hydrogenic impurity increases with increasing the cyclotron frequency of the magnetic field, the confinement strength of QRs and the temperature, but decreases with increasing the electron-phonon coupling strength and the dielectric constant ratio. The stability of the ground state of magnetopolarons is closely related to the aspect ratio e′of the QR. The ground state of magnetopolarons is the most stable at e′=1. The stability of the ground state of magnetopolarons can remarkably decrease when the value of the aspect ratio increases or decreases from 1.
