Effect of As preadsorption on InAs nanowire heteroepitaxy on Si(111) : A first-principles study

Arsenic preadsorption has recently been found to be crucial for selective-area epitaxial growth of oriented III-V semiconductor nanowires on Si(111). To understand the effect of preadsorption on the heteroepitaxy, this first-principles study examines the structure of As-adsorbed Si(111) surfaces. Reconstruction models such as adatom, trimer, and dimer-adatom-stacking fault structures are found to be metastable. The stability of unreconstructed arsenide structure (1×1-As) is confirmed but the faulted and unfaulted domains of 1×1-As are found to be practically degenerate in energy. These domains can therefore coexist on a Si(111)-As surface, and then epitaxial growth will be disrupted at domain boundaries where translational symmetry is broken. Indium adsorption on the Si(111)-As surface, however, destabilizes unfaulted domains, thus assisting its transformation into a coherent surface that allows epitaxy. This effect is attributed to the interlayer covalent interactions induced by In p electrons.