Energy-band alignments of Hf O2 on p-GaAs substrates

Interfacial reaction and the energy-band alignments of Hf O2 films on p-GaAs substrate were investigated by using x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. It has been demonstrated that the alloying of Hf O2 with Al2 O3 (HfAlO) can significantly reduce native oxides formation and increases the valence-band offsets (VBOs) at Hf O2 p-GaAs interface. In addition, the effects of Si interfacial passivation layer on band alignments have also been studied. VBO at Hf O2 p-GaAs, HfAlOp-GaAs, and Hf O2 Sip-GaAs interfaces were 2.85, 2.98, and 3.07 eV, respectively.