Structure of the Bi/Inp(110) Interface - a Photoemission Extended X-Ray Absorption Fine-Structure Study

We studied the Bi/InP(110) interface for 0.35- and 0.9-monolayer (ML) Bi coverages by photoemission extended x-ray absorption fine-structure (PEXAFS). P 2p PEXAFS data were acquired. The data were analyzed by Fourier filtering followed by phase analysis using a novel curve-fitting procedure in which the E0 is also floated. For 0.9-ML Bi/InP(110), the results show that Bi grows epitaxially and the P-Bi bond length is 2.42 +/- 0.05 angstrom. The first P-In nearest neighbor distance is determined as 2.46 +/- 0.05 angstrom, which is almost equal to the P-In bond length for the clean InP(110) surface and the bond length is 3% contracted in comparison to its value for bulk InP. Note that the surface states for the clean InP(110) surface are pushed out of the band gap due to surface relaxation. Hence, the interface states due to the atomic geometries of the substrate at the interface may not influence Schottky barrier formation to cause Fermi-level pinning. The P-P and P-Bi bond lengths in the second near-neighbor distance were determined as 4.17 +/- 0.06 and 4.26 +/- 0.06 angstrom, respectively.