| AVS 55th International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Wednesday Sessions |
| Session NS+NC-WeM |
| Session: | Characterization and Imaging of Nanostructures |
| Presenter: | B. Vlahovic, North Carolina Central University |
| Authors: | I. Filikhin, North Carolina Central University J. Nimmo, North Carolina Central University M.H. Wu, North Carolina Central University B. Vlahovic, North Carolina Central University |
| Correspondent: | Click to Email |
We model InGaAs/GaAs quantum heterostuctured objects, such as quantum dots (QD) and quantum rings (QR), in limit of small sizes. The electronic structure of these objects is restricted to a few electron and hole levels.1 For QDs with small sizes, the effect of non-parabolicity of the conduction band becomes very important. In our model, this effect is taken into account using the Kane formula. In this study we apply an effective approach in which the combined effect of strains, piezoelectricity and interband interactions are simulated by an effective potential.2 Based on our model, we performed an analysis of capacitance-gate-voltage data1 and photoluminescence spectra for QDs, QRs and for double concentric QRs. We show that our approach reproduces both the few electron energy level spectra and the increase of the electron effective mass relative to the bulk value due to non-parabolicity. In this case the effective mass of excited states must be energy dependent and differs from the ground state value. Also, the non-parabolic effect visibly shifts the electron energy levels in comparison with parabolic models. We include heavy holes into the model of band structure using the effective potential approach. This model allows us to reproduce measured transition energies and Coulomb shifts for excitonic complexes (X-, X+, XX).3 Ga and In material mixing in InGaAs/GaAs QD4 is also taken into account in this study. We compare our results with those obtained by kp-calculations5 and atomistic pseudopotential models.3 We note that calculations that model QDs from first principles are of fundamental interest, but our effective potential method has strong application significance, which will be appreciated by industry, due to its efficiency and accuracy in calculating physical properties. This work is supported by the DoD: W911NF-05-1-0502.
1 B. T. Miller, et al. Phys. Rev. B 56, 6764 (1997); R.J. Warburton, et al. Phys. Rev. B 58, 16221 (1998); A. Lorke, et al. Phys. Rev. Lett. 84, 2223 (2000).
2 I. Filikhin, et al. Phys. Rev. B 73, 205332 (2006).
3 S. Rodt, et al. Phys. Rev. B 71, 155325 (2005); G. Narvaez et al. Phys. Rev. B 72, 245318 (2005).
4 I. Kegel, et al. Phys. Rev. Lett. 85, 1694 (2000).
5 J. I. Climente, et al., J. Phys.:Condens. Matter 17, 1573, (2005); A. Schliwa, et al., Phys. Rev. 76, 205324 (2007).