“…For this, we carried out complete HVPE experimental investigations from the analysis of the type of substrate (GaN templates/c-plane sapphire or bare c-plane sapphire), stripe orientations /1 1 À 2 0S and /1 À 1 0 0S, carrier gas composition [28], growth temperature and V/III ratio influence. From this cartography and by fixing the appropriate experimental parameters, growth of GaN quasi-substrates or GaN nano-structures is totally controlled.…”