Band offsets for the (100), (110), (111), and (1¯ 1¯ 1¯) orientations of the GaAs/AlAs heterojunction are calculated in a tight-binding approach. A charge-neutrality condition is used. Some face-orientation dependence is obtained: the offset of the (110) interface (0.63 eV) is different from those of polar interfaces (0.49, 0.51, and 0.47 eV). This result differs from some other recent calculations and the origin of this difference is discussed. The predicted (100) offset is in good agreement with recent experiments. The potential barrier appears to be not exactly abrupt but extends over a few planes. This effect will be very important in the case of superlattices made from very thin layers. The HgTe/CdTe heterojunction is also considered. The extension to heterojunctions with no common anion is finally discussed.

• Received 9 February 1987

DOI:https://doi.org/10.1103/PhysRevB.36.1105