Comparative study of atomic-layer-deposited stacked (HfO ₂/Al₂O₃) and nanolaminated (HfAlO_x) dielectrics on In_0.53Ga_0.47As

The high-k gate dielectric structures in stacked (HfO₂/Al ₂O₃) and nanolaminated (HfAlO_x) forms with a similar apparent accumulation capacitance were atomic-layer-deposited on n-type In_0.53Ga_0.47As substrates, and their electrical properties were investigated in comparison with a single-layered HfO₂ film. Al-oxide interface passivation in both forms proved to be effective in preventing a significant In incorporation in the high-k film and reducing the interface state density. The measured valence band spectra in combination with the reflection electron energy loss spectra were used to extract the energy band parameters of various dielectric structures on In_0.53Ga _0.47As. A further decrease in the interface state density was achieved in the stacked structure than in the nanolaminated structure. However, in terms of the other electrical properties, the nanolaminated sample exhibited better characteristics than the stacked sample, with a smaller border trap density and lower leakage current under substrate injection conditions with and without voltage stressing.