Nonrectangular quantum wells as a basis for studying the band offsets at GaAs-Ga1-xAlx As interfaces

Using the envelope-function formalism we calculate interband-transition energies for various shapes of effective quantum-well potentials generated by layers of GaAs and Ga1-xAlxAs. The sensitivity of these experimentally accessible energies to variations in the band-offset parameter Qe is studied for rectangular, parabolic, triangular, and somewhat more complicated potential profiles. We show that this sensitivity may vary strongly for different profiles. Upon consideration of our numerical results as well as fabricational aspects we suggest that a triangular rather than a parabolic or rectangular quantum well should be used to determine Qe.