TEM-EDS analysis of the HfO
/GaAs pattern. (a) Cross-section TEM image of a 100nm-wide HfO2 mesa stripe and a GaAs trench after nanostructuring. (b) Corresponding EDS elemental maps for O (K), Hf (M), Ga (L), and As (L). The amorphous layer located at the trench bottom surface is constructed of gallium oxide. Hf is concentrated in the mesa stripe and side feet.