Conduction subbands in a GaAs/AlxGa1-xAs quantum well: Comparing different kp models

Abstract

The energy dispersion of the conduction subbands in a GaAs/AlxGa1-xAs superlattice is calculated by using a kp Hamiltonian that includes different number of bands. The most accurate model includes the Γ6c, Γ7v, Γ8v, Γ7c, and Γ8c bands. The resulting subband dispersion is compared with that obtained when the coupling of the Γ6c band with the Γ7v and Γ8v and/or Γ7c and Γ8c bands is neglected. We also consider the 2×2 kp Hamiltonian with terms up to the order k4. The subband dispersions are analyzed quantitatively by fitting the numerical result to the analytical expression obtained with the invariant expansion technique. The subbands are found to be significantly different with the various models. The differences are ascribed to the different bulk band dispersions obtained with different kp Hamiltonians and to the variation of the band parameters in the well and barrier materials. © 1992 The American Physical Society.