The valence-band offset between GaAs and AlGaAs has been found to be independent of crystal orientation, as deduced from measurements of the two-dimensional hole densities in ${\mathrm{Al}}_{0.26}$${\mathrm{Ga}}_{0.74}$As/GaAs heterojunctions. An analysis of the charge transfer yields a valence-band offset of 0.39±0.02 of the energy-gap difference.

• Received 4 February 1985

DOI:https://doi.org/10.1103/PhysRevB.31.6890