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External Electric Field Effect on Electronic and Optical Properties in InGaN/GaN Low Dimensional Systems

Author: ZengZaiPing
Tutor: WeiShuYi；XiaCongXin
School: Henan Normal
Course: Condensed Matter Physics
Keywords: A multiple quantum well External electric field Donor impurity Exciton Binding energy Quantum dots
CLC: O471.1
Type: Master's thesis
Year: 2011
Downloads: 31
Quote: 0
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Abstract

Effective mass approximation, using a hydrogen-type trial wave function, use a variational method to systematically study the influence of external electric field on the hydrogenic impurity in the zinc blende InGaN / GaN coupled quantum wells. In the calculation process, we consider a multi-quantum well well width, the thickness of the barrier layer, the impurity position and the external electric field strength of the donor impurity binding energy. Detailed analysis and discussion of the numerical results obtained, the following conclusions: With the quantum well well width increases, is located in the left well at the center of the multi-quantum well impurities impurity binding energy with the increase of the quantum well, one of the greatest value; impurities located in the multi-quantum well in the middle of the trap and right well impurity binding energy as well width increases monotonously decreases; With the increase in the thickness of the barrier layer, since the influence of the external electric field, in the multi-quantum at the center of the trap left trap impurities impurity bound first increases and then tends to be unchanged; shackles can not increase as the external electric field when the external electric field is strong enough, is located in each of the well of the multi-quantum well at the center of impurity impurity large change; when the quantum well is gradually increased in a multiple quantum well at the center of the left trap impurities impurity binding energy with the changes in the external electric field has a maximum value. Moreover, the maximum binding energy corresponding to the critical electric field decreases gradually with the increase of quantum well well width. In order to study the impact of the sphalerite of InGaN / GaN single quantum dot exciton and optical properties of the external electric field, the effective mass approximation, using Gaussian trial wave function, and use of the variational method detailed calculations of quantum little high the quantum limited potential external electric field intensity of the ground state of the quantum dot exciton binding energy interband transition energy of the ground state oscillator strength and linear optical polarizability. The main conclusions are as follows: the case of any electric field, the exciton binding energy, the interband transition energy decreases with increasing the Quantum little high; consider the influence of the external electric field, the exciton binding energy, the energy of the interband transitions Quantum little increases quickly lower; addition, the oscillator strength will be enhanced with the external electric field decreases rapidly; when little high quantum relatively large, external electric field on excitons in quantum dots and light-emitting properties of more obvious; exciton binding energy and oscillator strength increases with increasing In content. In content is relatively small, the exciton binding energy changes in the content of In more sensitive; decreases with the increase of the external electric field, the strength of the linear optical polarizability of the ground state. In order to study the sphalerite an InGaN / GaN asymmetric coupled quantum dots in hydrogenic impurity states effective mass approximation using Gaussian trial wave function, the use of the variational method to study quantum little bit high, middle barrier width, impurity position donor impurity position. The main conclusions are as follows: With the change of the impurity position impurity bound to have a maximum value; widest point of the impurities in the asymmetric coupled quantum dots, the donor binding energy. In addition, changing any of the non-symmetric coupled quantum dots a point will impurity bound to have a very significant impact. When the impurities in the widest point of the non-symmetric coupled quantum dots, impurity bound intermediate barrier layer is not sensitive (intermediate barrier layer). In order to study the impact of the external electric field of zinc blende InGaN / GaN asymmetric coupled quantum dots in the class hydrogen impurity states, the effective mass approximation using Gaussian trial wave function, use a variational method to study quantum little high, intermediate barrier width, impurity position and the impact of external electric field on the binding energy of a donor impurity. Detailed analysis and discussion of the numerical results obtained, the following conclusions: outstanding under the influence of an electric field, the donor binding energy has a maximum value, corresponding to the maximum impurity located at the right point in symmetric coupled quantum dots (electric field inverse forward to the growth direction of the quantum dots). When the Quantum little high increases, the donor binding energy decreases (located right quantum dot at the center of the impurities except). Of particular note is that when the impurity is located in the right quantum dot at the center, when the barrier layer (outside the electric field) in the relatively thick (large), the donor binding energy change of the barrier layer (outside the electric field) is not sensitive.

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