The evolution of clean, In-terminated $\mathrm{InP}\mathrm{}\left(100\right)-(2\mathrm{}\times 4)$ surfaces is investigated by synchrotron-radiation-excited photoemission spectroscopy as a function of annealing temperature. As-prepared $\mathrm{InP}\mathrm{}\left(100\right)-(2\mathrm{}\times 4)$ surfaces are found to be free of metallic indium, and the $4d$ core level shows two clear surface components. A third, indium-cluster-related component appears after annealing above $360\pm 10°\mathrm{C},$ due to phosphorous desorption, and is accompanied by a corresponding reduction in intensity in the In-P surface component. Further annealing leads to a decrease in binding energy of the indium-cluster-related peak due to increased metallicity and hence core-hole screening in the clusters. The increasingly metallic nature of the indium clusters is also revealed by the appearance and growth of a Fermi edge in valence-band spectra.

• Received 18 December 2001

DOI:https://doi.org/10.1103/PhysRevB.66.075323