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Anisotropy of the electron energy levels in InxGa1−xAs/GaAs quantum dots with non uniform composition |
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| Authors: | M.A. Migliorato D. Powell E.A. Zibik L.R. Wilson M. Fearn J.H. Jefferson M.J. Steer M. Hopkinson A.G. Cullis |
| Affiliation: | aDepartment of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom;bDepartment of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom;cQinetiQ plc, Sensors & Electronics Division, St.Andrews Road, Malvern, Worcs. WR14 3PS, United Kingdom |
| Abstract: | Atomistic simulations that use the Tersoff empirical potential accurately reproduce the effects of the presence of compositional disorder in strained semiconductor alloys. This method is applied to InGaAs quantum dot islands, for which gradients in the In composition distribution have been observed and accurately measured, and we demonstrate that the internal piezoelectric fields contribute strongly to the nature of the electron wavefunctions. The theoretical predictions are supported by experimental evidence: intersubband absorption measurements confirm that the p-states degeneracy for the electron first excited state is lifted and a minimum splitting of at least 5 meV is to be generally expected. |
| Keywords: | Quantum dots Piezoelectric field Spectroscopy |
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