Energy-band alignment of Al2O3 and HfAlO gate dielectrics deposited by atomic layer deposition on 4H-SiC

Energy band alignment and band gap of Al2O3 and HfAlO films grown by atomic layer deposition on 4H-SiC were determined using x-ray photoelectron spectroscopy. Al2O3 exhibited a symmetric band profile with a conduction band offset (Delta E-C) of 1.88 eV and a valence band offset (Delta E-V) of 1.87 eV. HfAlO yielded a smaller Delta E-C of 1.16 eV and Delta E-V of 1.59 eV. The higher dielectric constant and higher effective breakdown field of HfAlO compared to Al2O3, coupled with sufficient electron and hole barrier heights, makes it a potential dielectric for use on 4H-SiC, and provokes interest in further investigation of HfAlO/4H-SiC properties.