Fermi level unpinning achievement and transport modification in Hf1-xYbxOy/Al2O3/GaSb laminated stacks by doping engineering

•Interface chemistry and transport characteristics determination of Hf1-xYbxOy/Al2O3/GaSb gate stacks have been achieved.•Hf1-xYbxOy/Al2O3/GaSb (x = 0.32) gate stack has demonstrated the optimized interface stability and the suppressed leakage current density of 2.23×10–5 A cm-2.•The energy distribution of interface state has confirmed the achievement of the lowest interface state density of 1.98×1013 eV-1 cm-2, resulting in Fermi level unpinning.