Reaction paths of alane dissociation on the Si(0 0 1) surface

Building on our earlier study, we examine the kinetic barriers to decomposition of alane, AlH₃, on the Si(0 0 1) surface, using the nudged elastic band approach within density functional theory. We find that the initial decomposition to AlH with two H atoms on the surface proceeds without a significant barrier. There are several pathways available to lose the final hydrogen, though these present barriers of up to 1 eV. Incorporation is more challenging, with the initial structures less stable in several cases than the starting structures, just as was found for phosphorus. We identify a stable route for Al incorporation following selective surface hydrogen desorption (e.g. by scanning tunneling microscope tip). The overall process parallels PH₃, and indicates that atomically precise acceptor doping should be possible.