Theoretical study of electronic and optical properties of inverted GaAs/Al_xGa_(1-x)As quantum dots with smoothed interfaces in an external magnetic field

摘要

Magneto-optics of unstrained GaAs/Al_xGa_(1-x)As quantum dots are investigated theoretically in the presence of an external magnetic field. Single-particle states, exciton binding energies, and the exciton diamagnetic shift are calculated with a confinement potential based on atomically resolved scanning tunneling microscopy pictures. The degree of interface intermixing is treated as a variable. The electronic structure of the dot in the presence of a magnetic field is calculated using eight-band k · p theory including a magnetic field. We find that varying interface roughness sensitively affects the interband but hardly the intraband energies. For magnetic fields applied both in the growth direction and perpendicular to it (for B ≤ 50 T), we find good agreement between our predicted exciton diamagnetic shift and recent experimental magnetophotoluminescence data [N. Schildermans et al., Phys. Rev. B 72, 115312 (2005)]. The inherent coupling of valence and conduction bands taken into account in the eight-band k · p model explains well the observed experimental results.