Structural characteristics of gallium metal deposited on Si (0Â 0Â 1) by MOCVD

The epitaxial growth of high quality gallium containing III/V material on silicon offers a wide field of possible applications. While the growth of III/V material has already been studied extensively, little is known about the atomic processes at the interface between silicon and the III/V material. Here we study the deposition of gallium on silicon (0 0 1) by metal organic chemical vapour deposition for the two different precursors triethyl gallium and trimethyl gallium, the influence of varying growth conditions as well as the influence of an annealing after growth. We use atomic force microscopy and high angle annular dark field scanning transmission electron microscopy to analyse the detailed structures occurring for this deposition. For all conditions studied, pyramidal gallium containing structures form in the silicon with boundaries on the silicon {1 1 1} lattice planes. The pyramidal etching structures can be reproduced in straightforward kinetic Monte Carlo simulations of the growth process. When triethyl gallium is used, those structures are covered by carbon containing passivating mounds. After an additional annealing at 800 °C no gallium can be detected anymore for any sample, while an annealing at considerably lower temperatures leads to an alteration of the silicon gallium alloy.