MUGHNETSYAN Vram Yerevan State University

Effect of Interdiffusion on Band Structure in GaAs/Ga1-XAlXAs Quantum Ring Superlattices


Quantum rings (QR) are of great interest due to their unique electronic, magnetic, and optical properties [1]–[2]. Quantum phase coherence effects on carrier transport such as in the Aharonov-Bohm and Aharonov-Casher effects are observed in QRs [3]. During the last decade impressive progress has been made in the field of manufacturing of ordered structures composed of QRs [4]-[6]. Recently arrays of strain-free GaAs/Al0.33Ga0.67As QRs have been fabricated by droplet epitaxy [5]. It is shown that the rapid thermal annealing (RTA) plays a major role in modifying the electronic structure and in the improvement of material quality. The effect of interdiffusion on band structure of superlattices (SL) composed of initially cylindrical GaAs/Ga1-xAlxAs quantum rings is investigated. Two cases of superlattices, namely, a three-dimensional superlattice composed of Gaussian-shaped double quantum rings (GSDQR) and an one layer QR SL are considered. Following Gunawan et. al. [7], Fourier transformation to momentum space is used to solve the Schrödinger equation. In the case of one layer SL the adiabatic approximation is used to take into consideration the transversal motion of electron. Below we present the main obtained results. 1. Due to interdiffusion the SL potencial symmetry superimposes on the cylindrical one of QRs. 2. The smearing of the potential profile leads to the shift of the dispersion curves to the higher energy regions and to the minibands broadening. 3. In the case of GSDQR SL the dispersion curves in the direction parallel to the QRs axes differs from ones in other directions qualitatively even for the SL of cubic symmetry, however this difference gradually disappears with the increase of diffusion parameter. 4. In the case of one layer QR SL the consideration of the dependence of electron effective mass on diffusion parameter and spatial coordinates leads to the decrease of electron energy up to 10meV. The obtained results indicate to the opportunity of purposeful manipulation of structure characteristics by means of interdiffusion. This work was supported by Armenian National Science and Education Fund (ANSEF) grant “nano-3334”. LITERATURE [1] W.H. Chang, C.H. Lin, Y.J. Fu, T.C. Lin, H. Lin, S.J. Cheng, S.D. Lin, and C.P. Lee, Nanoscale Res. Lett. 5, 680 (2010). [2] N.A. J. M. Kleemans, I. Bominaar-Silkens, V.M. Fomin, V.N. Gladilin, D. Granados, A.G. Taboada, J.M. Garcia, P. Offermans, U. Zeitler, P.C.M. Christianen, J.C. Maan, J.T. Devreese, P.M. Koenraad, Phys. Rev. Lett. 99, 146808 (2007). [3] M. Zarenia, J.M. Pereira, F.M. Peeters, and G.A. Farias, Nano Lett. 9, 4088 (2009). [4] J. Wu, D. Shao, Zh. Li, M.O. Manasreh, V.P. Kunets, Zh.M. Wang, G.J. Salamo, Appl. Phys. Lett. 95, 071908 (2009). [5] J. Wu, Zh.M. Wang, V.G. Dorogan, Sh. Li, J. Lee, Y.I. Mazur, E.S. Kim, G.J. Salamo, Nanoscale Research Letters 8:5 (2013). [6] Sh. Huang, Zh. Niu, Zh. Fang, H. Ni, Z. Gong et al., Appl. Phys. Lett. 89, 031921 (2006). [7] O. Gunawan, H.S. Djie, B.S. Ooi, Phys. Rev. B 71, 205319 (2005).