Tunnel spectroscopy of the AlGaAs-GaAs heterostructure interface

The material interface of a molecular beam epitaxy grown Al 0.5Ga0.5As-GaAs heterostructure is investigated on a cross-sectional (110) cleavage plane using tunnel spectroscopy. The depleted n-type region and the electron confinement layer adjacent to the interface are identified with local current-voltage spectroscopy. The spatial width of these layers is close to 15 nm. The spectroscopy can be interpreted with the valence-band offset in the interface, and a value of 0.35 eV is found for this quantity.