The dissociative adsorption of borane on the Ge(1 0 0)-2 × 1 surface: A density functional theory study

By means of cluster models coupled with density functional theory, we have studied the hydroboration of the Ge(1 0 0)-2 × 1 surface with BH3. It was found that the Ge(1 0 0) surface exhibits rather different surface reactivity toward the dissociative adsorption of BH3 compared to the C(1 0 0) and Si(1 0 0) surfaces. The strong interaction still exists between the as-formed BH2 and H adspeices although the dissociative adsorption of BH3 on the Ge(1 0 0) surface occurs readily, which is in distinct contrast to that on the C(1 0 0) and Si(1 0 0) surfaces. This can be understood by the electrophilic nature of the down Ge atom, which makes it unfavourable to form a GeH bond with the dissociating proton-like hydrogen. Alternatively, it can be attributed to the weak proton affinity of the Ge(1 0 0) surface. Nevertheless, the overall dissociative adsorption of BH3 on group IV semiconductor surfaces is favourable both thermodynamically and kinetically, suggesting the interesting analogy and similar diversity chemistry of solid surface in the same group.