Band alignment of HfO_2/AlN heterojunction investigated by X-ray photoelectron spectroscopy

摘要

The band alignment between AlN and Atomic-Layer-Deposited (ALD) HfO_2 was determined by X-ray photoelectron spectroscopy (XPS). The shift of Al 2p core-levels to lower binding energies with the decrease of take-off angles 6 indicated upward band bending occurred at the AlN surface. Based on the angle-resolved XPS measurements combined with numerical calculations, valence band discontinuity ΔE_V of 0.4 ± 0.2 eV at HfO_2/AlN interface was determined by taking AlN surface band bending into account. By taking the band gap of HfO2 and AlN as 5.8 eV and 6.2 eV, respectively, a type-Ⅱ band line-up was found between HfO_2 and AlN.