Direct evidence of C-60 chemical bonding on Si(100)

The deposition of C-60 on Si(100):H2 x 1 surface was investigated as a func tion of substrate temperature in the range RT-800 degrees C by means of pho toemission spectroscopies. In this range, the interaction of C-60 molecules with both the hydrogenated and the bare Si(100)2 X 1 surface could be stud ied and followed until the temperature was high enough to cause the fragmen tation of C-60 cage and the formation of SiC layers. Its found that the ful lerene molecules physisorb on the hydrogenated surface but form a covalent bond on the clean surface. The transition from physisorption to chemisorpti on entails the appearance of a new peak in the ultraviolet photoemission sp ectroscopy spectra intermediate between that of the HOMO (highest occupied molecular orbital) and HOMO-I bands. [S0163-1829(99)03216-6].