In overlayers on Si(111)7×7 : growth and evolution of the electronic structure

The formation of thin overlayers of In on Si(111)7×7 substrate surfaces has been studied in the temperature range from room temperature to ∼500 o C by Auger-electron spectroscopy, low-energy electron diffraction, direct and inverse photoemission spectroscopy (UPS and IPES), and electron-energy-loss spectroscopy (EELS). Up to In coverages Θ ln of about 1-2 monolayers (ML), uniform layer growth prevails irrespective of the substrate temperature, but ordered surface structures can only be observed at elevated temperatures. Beyond Θ ln =1-2 ML, three-dimensional island clustering according to the Stranski-Krastanov mechanism appears, but the growth rate appears to be greatly reduced for substrate temperatures >300 o C