Nanometre thin high-k hafnium oxide (HfO 2) or Hf silicate layers combined with a sub-nm SiO 2 layers have become Si compatible gate dielectrics. Medium energy ion scattering (MEIS) analysis has been applied to a range of such MOCVD grown HfO 2/SiO 2 and HfSiOx (60% Hf)/SiO 2 gate oxide films of thickness between 1 and 2 nm on top of Si (100), before and after decoupled plasma nitridation (DPN). MEIS in combination with energy spectrum simulation provides quantitative layer information with sub-nm resolution ...