کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5426382 | 1395889 | 2006 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Hydrogen-induced metallization of the 3C-SiC(0 0 1)-(3 Ã 2) surface Hydrogen-induced metallization of the 3C-SiC(0 0 1)-(3 Ã 2) surface](/preview/png/5426382.png)
A surprising metallization of the SiC(0Â 0Â 1)-(3Â ÃÂ 2) surface induced by hydrogen adsorption was discovered in recent experiments. The effect was ascribed to dangling bonds created on the third layer of the surface system by H adsorption and stabilized by steric hindrance. We have investigated the surface metallization by density functional calculations. Our total-energy minimizations show that dangling bonds on the third layer are very unstable. Instead, H adatoms form angular Si-H-Si bonds on the third layer after the asymmetric dimers on the top layer have been saturated by H forming monohydrides. The novel Si-H-Si bonds on the third layer give rise to a metallic surface, indeed. But the mechanism for metallization is very different from the one suggested originally. Likewise, H atoms can also occupy bridge positions in angular Si-H-Si bonds on the second layer and induce metallization, as well. In addition to monohydrides on the top-layer dimers, we have also investigated dihydride surfaces with additional H on the second and/or third layer. The dihydride surface structure with H adsorbed on both the second and third layers is energetically most favorable and is also metallic. In all three cases the new Si-H-Si bonds are the origin of the surface metallization while its nature is somewhat more intricate, as will be discussed.
Journal: Surface Science - Volume 600, Issue 18, 15 September 2006, Pages 3564-3569