Reaction paths of alane dissociation on the Si(001) surface

TL;DR

This study investigates the dissociation pathways of alane on Si(001) surface using DFT and NEB, revealing low barriers for initial decomposition and potential routes for atomic-scale doping.

Contribution

It provides detailed kinetic barrier analysis for alane dissociation on Si(001), highlighting stable incorporation pathways and parallels with phosphorus doping.

Findings

Initial AlH decomposition occurs without significant barrier.

Final hydrogen removal pathways have barriers up to 1 eV.

Stable Al incorporation is possible via surface hydrogen desorption.

Abstract

Building on our earlier study, we examine the kinetic barriers to decomposition of alane, AlH$_3$, on the Si(001) surface, using the nudged elastic band (NEB) approach within DFT. 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 STM tip). The overall process parallels PH$_3$, and indicates that atomically precise acceptor doping should be possible.