Band discontinuity in the GaAs/AlAs interface studied by in situ photoemission spectroscopy

In order to investigate the valence-band discontinuity of the GaAs/AlAs interface, the thickness dependence of the photoemission spectra of a GaAs layer in situ deposited on AlAs by molecular-beam epitaxy has been studied. Although the interface is atomically abrupt, the electronic structure in the interface region displays Al1-xGaxAs alloy-like behaviors. The valence-band maximum as well as the Ga 3d core level show a gradual shift as a function of GaAs layer thickness of less than 2 nm (8 monolayers), which indicates that interface formation needs about 2 nm thickness for the electronic structure of the GaAs layer to become that of bulk GaAs. (C) 2002 American Institute of Physics.