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Polaron effect on the optical rectification in spherical quantum dots with electric field 被引量:5
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作者 冯振宇 闫祖威 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第10期446-451,共6页
The polaron effect on the optical rectification in spherical quantum dots with a shallow hydrogenic impurity in the presence of electric field is theoretically investigated by taking into account the interactions of t... The polaron effect on the optical rectification in spherical quantum dots with a shallow hydrogenic impurity in the presence of electric field is theoretically investigated by taking into account the interactions of the electrons with both confined and surface optical phonons. Besides, the interaction between impurity and phonons is also considered. Numerical calculations are presented for typical Zn1-xCdxSe/ZnSe material. It is found that the polaronic effect or electric field leads to the redshifted resonant peaks of the optical rectification coefficients. It is also found that the peak values of the optical rectification coefficients with the polaronic effect are larger than without the polaronic effect, especially for smaller Cd concentrations or stronger electric field. 展开更多
关键词 polaron effect optical rectification spherical quantum dot
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Optical properties of core/shell spherical quantum dots 被引量:1
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作者 Shuo Li Lei Shi Zu-Wei Yan 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第9期536-542,共7页
In this study,the effects of quantum dot size on the binding energy,radiative lifetime,and optical absorption coefficient of exciton state in both GaN/AlxGa1-xN core/shell and AlxGa1-xN/GaN inverted core/shell quantum... In this study,the effects of quantum dot size on the binding energy,radiative lifetime,and optical absorption coefficient of exciton state in both GaN/AlxGa1-xN core/shell and AlxGa1-xN/GaN inverted core/shell quantum dot structures are studied.For the GaN/AlxGa1-xN core/shell structure,the variation trend of binding energy is the same as that of radiation lifetime,both of which increase first and then decrease with the increase of core size.For AlxGa1-xN/GaN inverted core/shell structure,the binding energy decreases first and then increases with core size increasing,and the trends of radiation lifetime varying with core size under different shell sizes are different.For both structures,when the photon energy is approximately equal to the binding energy,the peak value of the absorption coefficient appears,and there will be different peak shifts under different conditions. 展开更多
关键词 spherical quantum dot binding energy optical absorption coefficient exciton radiation lifetime
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Lifetime of resonant state in a spherical quantum dot 被引量:1
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作者 李春雷 肖景林 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第1期67-71,共5页
This paper calculates the lifetime of resonant state and transmission probability of a single electron tunnelling in a spherical quantum dot (SQD) structure by using the transfer matrix technique. In the SQD, the el... This paper calculates the lifetime of resonant state and transmission probability of a single electron tunnelling in a spherical quantum dot (SQD) structure by using the transfer matrix technique. In the SQD, the electron is confined both transversally and longitudinally, the motion in the transverse and longitudinal directions is separated by using the adiabatic approximation theory. Meanwhile, the energy levels of the former are considered as the effective confining potential. The numerical calculations are carried out for the SQD consisting of GaAs/InAs material. The obtained results show that the bigger radius of the quantum dot not only leads significantly to the shifts of resonant peaks toward the low-energy region, but also causes the lengthening of the lifetime of resonant state. The lifetime of resonant state can be calculated from the uncertainty principle between the energy half width and lifetime. 展开更多
关键词 spherical quantum dot lifetime of resonant state transmission probability
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Linear and Nonlinear Optical Properties in Spherical Quantum Dots 被引量:1
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作者 Yusuf Yakar Bekir Cakir Ayhan Ozmen 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第6期1185-1189,共5页
We calculate the energy eigenvalues and the sate functions of one-electron Quantum Dot (QD) by using a combination of Quantum Genetic Algorithm (QGA) and Hartre-Fock-Roothaan (HFR) method. The linear and the thi... We calculate the energy eigenvalues and the sate functions of one-electron Quantum Dot (QD) by using a combination of Quantum Genetic Algorithm (QGA) and Hartre-Fock-Roothaan (HFR) method. The linear and the third-order nonlinear optical absorption coefficients for the 1s-1p, 1p-1d, and 1d-1f transitions are examined as a function of the incident photon energy for three different values of the stoichiometric ratio. The results show that the stoichiometric ratio, impurity, relaxation time, and dot size have great influence on the optical absorption coefficients of QDs. 展开更多
关键词 optical properties spherical quantum dot QGA and HFR method
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H_2^+-Like Impurities Confined by Spherical Quantum Dots:a Candidate for Charge Qubits
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作者 KANG Shuai LIU Yi-Ming SHI Ting-Yun 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第9期767-770,共4页
We have calculated the electron energy of the ground and lower excited states for H_2^+-like impurity statesconfined in finite spherical quantum dots in GaAs.Based on the characteristics of energy levels,we have propo... We have calculated the electron energy of the ground and lower excited states for H_2^+-like impurity statesconfined in finite spherical quantum dots in GaAs.Based on the characteristics of energy levels,we have proposed ascheme for realizing charge qubit composed by the the ground and the first excited states of this confined double donorsystem for the first time.In the proposed scheme the charge qubit is coded in terms of the located electronic states. 展开更多
关键词 spherical quantum dot charge qubit B-SPLINES H2^+-like impurities
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Effect of hydrostatic pressure and polaronic mass of the binding energy in a spherical quantum dot
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作者 A.Rejo Jeice Sr.Gerardin Jayam K.S.Joseph Wilson 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第11期92-97,共6页
Simultaneous effect of hydrostatic pressure and polaronic mass on the binding energies of the ground and excited states of an on-center hydrogenic impurity confined in a GaAs/GaA1As spherical quantum dot are theoretic... Simultaneous effect of hydrostatic pressure and polaronic mass on the binding energies of the ground and excited states of an on-center hydrogenic impurity confined in a GaAs/GaA1As spherical quantum dot are theoretically investigated by the variational method within the effective mass approximation. The binding energy is calculated as a function of dot radius and pressure. Our findings proved that the hydrostatic pressure led to the decrease of confined energy and the increase of donor binding energy. Conduction band non-parabolicity and the polaron masses are effective in the donor binding energy which is significant for narrow dots not in the confined energy. The maximum donor binding energy achieved by the polaronic mass in the ground and excited states are 2%-19% for the narrow dots. The confined and donor binding energies approach zero as the dot size approaches infinity. 展开更多
关键词 spherical quantum dot square well confinement confined energies effective mass approximation
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Simultaneous Effects of External Electric Field and Conduction Band Nonparabolicity on Optical Properties of a GaAs Quantum Dot Embedded at the Center of a GaAlAs Nano-Wire
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作者 Gh.Safarpour M.A.Izadi +2 位作者 M.Novzari E.Niknam M.M.Golshan 《Communications in Theoretical Physics》 SCIE CAS CSCD 2014年第6期765-772,共8页
An investigation of the optical properties of a GaAs spherical quantum dot which is located at the center of a Ga1-xAlx As cylindrical nano-wire has been performed in the presence of an external electric field. The ba... An investigation of the optical properties of a GaAs spherical quantum dot which is located at the center of a Ga1-xAlx As cylindrical nano-wire has been performed in the presence of an external electric field. The band nonparabolieity effect is also considered using the energy dependent effective mass approximation. The energy eigenvalues and corresponding wave functions are calculated by finite difference approximation and the reliability of calculated wave functions is checked by computing orthogonality. Using computed energy eigenvalues and wave functions, the linear, third-order nonlinear and total optical absorption coefficients and refractive index changes are examined in detail. It is found that (i) Presence of electric field causes both blue and red shifts in absorption spectrum; (ii) The absorption coefficients shift toward lower energies by taking into account the conduction band nonparabolicity; (iii) For large values of electric field the effect of conduction band nonparabolieity is less dominant and parabolic band is estimated correctly; (iv) In the presence of electric field and conduction band nonparabolicity the nonlinear term of absorption coefficient rapidly increases by increasing incident optical intensity. In other words, the saturation in optical spectrum occurs at lower incident optical intensities. 展开更多
关键词 nonlinear optics conduction band nonparabolicity electric field spherical quantum dot
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