SURFACE AND BULK EFFECTS IN EX-SITU HYDROGENATED ALPHA-SIC THIN-FILMS

The effect of ex-situ hydrogenation on the bulk and surface properties of amorphous SiC (alpha-SiC) thin films has been investigated using a number of bulk-and surface-sensitive characterisation techniques. The diffusion coefficient of deuterium in alpha-SiC is found to be equal to 3-4 x 10(-15) cm(2) s(-1). It is shown that atomic hydrogen causes drastic changes in the dielectric function, due to preferential Si etc hing from the film surface, and the formation of a carbon surface laye r rich in sp(2) bonds. Furthermore, the atomic hydrogen diffuses in th e bulk and causes an increase of the optical band gap and a concurrent decrease in conductivity, due to partial passivation of dangling bond s. (C) 1997 Elsevier Science S.A.