Inertness of SiC surfaces against Si atoms and clusters

Si atom and cluster interaction with 6H-SiC (0001) Si surfaces was studied using thermal desorption measurement and scanning tunneling microscopy (STM ), Heating SiC at 1500 degrees C in an ultrahigh vacuum produced an inert s urface. When this surface was exposed to Si vapor containing clusters, Si a toms and Si2-4 clusters were observed to recoil at 400 degrees C. STM showe d that the surface had a 6 root 3 x 6 root 3R30 degrees superstructure. The activation energy for thermal desorption of Si, Si-2, and Si, from the sur face was found to be 46, 49, and 66 meV. These low values indicate the phys isorption of Si atoms and clusters. STM showed that, when the surface was s upplied with Si vapor at room temperature, Si clusters formed at step edges , leaving the 6 root 3 x 6 root 3R30 degrees structure intact and verifying the surface's inertness. (C) 1999 Elsevier Science B.V. All rights reserve d.