Density functional study of H2 desorption from monohydride and dihydride Si(100) surfaces

✍ Scribed by A. Vittadini; A. Selloni

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 502 KB
• Volume: 235
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(95)00129-r

✦ Synopsis

We present a density functional study of H 2 adsorption on and desorption from Si(100)2 × 1 monohydride and Si(100)l × 1 dihydride surfaces, carried out using a slab geometry with large supercells. For the monohydride surface we find that two distinct mechanisms -i.e. the recombination of two H atoms sitting either on the same dimer or on adjacent dimers along a row -yield desorption barriers in agreement with experiment. For the dihydride surface, the preferred pathway involves the desorption of two H atoms belonging to the same Sill 2 unit. This is followed by a local structural rearrangement, leading to the formation of a surface dimer, and making the overall reaction slightly exothermic. The corresponding adsorption barrier, = 2 eV, is large with respect to that inferred from desorption experiments.