EVIDENCE OF NON-COMMUTATIVITY OF BAND DISCONTINUITIES IN INP-A(IN)AS-GA(IN)AS HETEROSTRUCTURES

In spite of the spatial separation of electrons and holes associated w ith its type II nature, the InP-Al(In)As system has excellent optical properties. In particular, it is possible to measure the photo-lumines cence excitation and photo-current spectra in single hetero-junctions. In addition, the bandgap of a type II heterostructure varies linearly with the discontinuity of the conduction bands. This system thus offe rs a unique opportunity for a detailed experimental study of the band offsets. We find that offsets at InP-Al(In)As and Al(In)As-InP heteroj unctions are quite reproducible, but differ by (100 +/- 20 meV). It al so appears that the average band offset is not transitive in the Ga(In )As-InP-Al(In)As family of heterostructures.