The growth morphology and electronic structure of the Bi/GaAs(110) interface are studied by high-resolution synchrotron-radiation photoelectron spectroscopy. Quantitative analysis of the Bi 5d, Ga 3d, and As 3d core levels, along with valence-band and low-energy electron diffraction results, indicate a modified Stranski-Krastanov growth mode for the first two monolayers of Bi on GaAs(110) followed by Bi island growth. Valence-band data show the development of electronic states between the GaAs valence-band maximum (VBM) and the Fermi level for a coverage of 0.5 monolayer (ML). By 1 ML of Bi, interface states are present up to the Fermi level ($E_F$) with a substantial density of states above the VBM and a peak in the interface density of states at 1.2 eV below $E_F$. Bi 5d core-level results show equal numbers of bonding sites for the Bi to the surface Ga and As atoms. Fitting of the core-level data indicates three Bi configurations assigned to Bi-Ga, Bi-As, and Bi-Bi bonding arrangements. Intensity attenuation profiles of the various core-level bonding arrangements allow for a detailed description of the overlayer growth mode and the determination of a second epitaxial Bi layer before the onset of island formation.

• Received 10 April 1989

DOI:https://doi.org/10.1103/PhysRevB.40.10412