Substrates preparation (cleaning, surface roughness, deoxidation, structuration, etc...) is a very important step for the quality of semiconductor epitaxy. It has become essential since the current research projects targets heteroepitaxy on silicon, epitaxial lateral growth over a dielectric mask, or epitaxy of nanostructures using surface etching, dielectric mask or metal nanoparticules deposition combined to VLS growth mode. During this workshop of the PULSE GDR, these topics will be addressed by invited talks followed by discussions about sample preparation and characterization methods before growth.