Influence of Al Composition on Donor Impurity States in Self-Formed GaAs-Al_xGa_1-xAs Quantum Rings

Abstract:

Based on the the effective mass approximation and variational approach, the donor impurity states confined in self-formed GaAs/Al_xGa_1-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/Al_xGa_1-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.

• Periodical: Applied Mechanics and Materials (Volumes 380-384)
• Pages: 4284-4289
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.380-384.4284
• Online since: August 2013
• Authors: Guang Xin Wang, Xiu Zhi Duan
• Keywords: Binding Energy, Hydrogenic Impurity, Quantum Ring

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