Ga induced 2D superstructural phase diagram on trenched Si(5 5 12) surface

The high index Si(5 5 12) surface offers morphological trenches, which can be interesting for epitaxial growth. In this study, the evolution of Ga adsorption at a very low flux rate of 0.03ML/min on high index trenched Si(5 5 12)−2×1 reconstructed surface at various substrate temperatures ranging from room temperature (RT) to 600°C has been investigated using in-situ AES, LEED and EELS. The Auger uptake curves, which plot the Ga(LMM)/Si(LVV) Auger intensity ratio with Ga adsorption time, show that Ga grows in layer plus islands mode for substrate temperatures in the RT to 350°C range, while it grows in Volmer–Weber (3D islands) for higher substrate temperatures (>350°C). We also arrive at a complete 2D superstructural phase diagram for Ga/Si(5 5 12) interfacial system that shows the pathways to attain the different superstructural phases. The formation of Ga nanowires as (2 2 5), (3 3 7) phase and Ga 3D islands in the (1 1 2)−6×1, (1 1 2)−6×2 phases and other Ga induced superstructural phases like (7 7 17)+2x(1 1 3), (2 2 5)+(3 3 7), 1×1 has been carefully followed. The electronic structures of each of the observed phases have been probed by EELS and each of them is shown to have characteristic features. ► Kinetics of adsorption and desorption of Ga on trenched Si(5 5 12)–2×1 surface. ► Formation of Ga nanowires, nanochains and 3D metal islands. ► A comprehensive phase diagram of Ga/Si(5 5 12) using AES and LEED observations.