H-Induced Reconstruction and Faceting of Al Surfaces

Abstract

First principles calculations show that chemisorbed H causes vacancy reconstructions and faceting of all Al low index surfaces. On Al(111) H-decorated vacancies are stable; on H-covered Al(100) vacancies are easily activated thermally. H-covered Al(110) forms a missing row reconstruction with H-decorated vacancies on the {l_brace}111{r_brace} microfacets. At high H coverages, low index Al surfaces are unstable against faceting. Al(111) and Al(110) form {l_brace}211{r_brace} facets, on Al(100) islands and pits with {l_brace}311{r_brace} and {l_brace}211{r_brace} facets are stable. The H-induced structural changes are caused by the preferential binding of H at low coordinated Al surface atoms and at {l_brace}100{r_brace} microfacets or, more generally, at {open_quotes}surface tetrahedral{close_quotes} sites. {copyright} {ital 1997} {ital The American Physical Society}