Cross-sectional scanning tunneling microscopy and spectroscopy of InGaP/GaAs heterojunctions

Compositionally abrupt InGaP/GaAs heterojunctions grown by gas-source molecular-beam epitaxy have been investigated by cross-sectional scanning tunneling microscopy and spectroscopy. Images inside the InGaP layer show nonuniform In and Ga distribution. About 1.5 nm of transition region at the interfaces is observed, with indium carryover identified at the GaAs–on–InGaP interface. Spatially resolved tunneling spectra with nanometer spacing across the interface were acquired, from which band offsets (revealing that nearly all of band offset occurs in the valence band) were determined. © 2004 American Institute of Physics.