THERMAL-PROPERTIES OF THE SN/SIO2 INTERFACE AS STUDIED BY SURFACE SPECTROSCOPIES

Vapor-deposited thin films of Sn (a few monolayers) on SiO2 substrates have been studied in the temperature range 100-1100 K under ultrahigh vacuum conditions. Auger spectroscopy measurements indicate that Sn forms clusters even for deposition at 100 K. Using line-of-sight mass spectroscopy, it has been found that Sn clusters desorb as Sn atoms near 850 K by zero-order kinetics with a desorption activation energy of 77+/-3 kcal/mol, a value near the enthalpy of sublimation of bulk Sn. Liquid Sn does not interdiffuse into SiO2, and there is no chemical interaction between Sn and SiO2.