We perform surface science experiments of sub-monolayer adsorption of group III metal on Silicon surfaces of various orientations and reconstructions. We use stable potential energy profiles of these surfaces to form low-dimensional nanostructures of the metal adsorbates. We have explored several aspects of the low index Si(100) and Si(111) surfaces and also on the high index Si(5 5 12) that has interesting 1-D faceted grooves enabling formation of single atom wide nanowire. We form 2D-superstructural phase diagram for these systems which indicate the pathways to be employed to attain desired structural and electronic properties. These submonolayer phases can also be template for growing epitaxial films and nanostructures