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Steady electromagnetic field in cylindrical quantum dots polaron temperature effect

Author: LiuMian
Tutor: LiZiJun
School: Yantai University
Course: Theoretical Physics
Keywords: Cylindrical Quantum Dot Electromagnetic Fields Temperature Polaron Vibration frequency Energy
CLC: O471.1
Type: Master's thesis
Year: 2008
Downloads: 48
Quote: 0
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Abstract


In this paper, an improved linear combination operator and unitary transformation with the variational method are combined in the effective mass approximation , polaron Hamiltonian in cylindrical quantum dots . By theoretical calculations , the vibration frequency of the polaron energy and the excitation energy is more precise analytical expression . By numerical calculation of the specific material , along the growth axis direction plus electric , magnetic field and temperature on the nature of the polaron in quantum dots . The conclusion is as follows : when the electron-phonon interaction is weak , the applied electric field makes the energy of the ground state in a lower position , plus the additional energy generated by the electric field is negative . Applied electric field also makes the growth direction of the energy level spacing decreases , which means that the quantum effects of the quantum dots will be weakened , but may increase the electronic transition probabilities , and the applied electric field makes the energy increases with increasing temperature , speed reduction slow . The external magnetic field makes the vibration frequency of the polaron ground state energy and the excitation energy has increased in varying degrees , which indicates that the external magnetic field can lead to the polarization of the quantum dots strengthen . And the applied magnetic field to increase the interval between the adjacent energy levels , the applied magnetic field can be of the quantum dots of the quantum effect is more obvious . As the temperature increases , the average number of polaron polaron vibration frequency , energy and the excitation energy will increases . Easier polarization in quantum dots under high temperature . When the strong interaction between electrons and phonons , the situation is slightly different . When the system is in the low-temperature limit , the electric field and the magnetic field on the nature of the polaron is the same as above . When the system at finite temperature , as the temperature rises , the average number of polaron polaron vibration frequency , energy and the excitation energy will increases . Applied electrical , magnetic fields are such that the polaron energy is reduced , and the applied electric field so that the energy increases as the temperature increases the speed .

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CLC: > Mathematical sciences and chemical > Physics > Semiconductor physics > Semiconductive Theory > Semiconductor quantum theory
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