Band offset determination of atomic-layer-deposited AI_2O_3 and HfO_2 on InP by internal photoemission and spectroscopic ellipsometry

摘要

Band offsets at the interfaces of n- and p-type InP ((100) and (111)A) and atomic-layer-deposited (ALD) Al_2O_3 were measured with internal photoemission and spectroscopic ellipsometry. Similarly, the band offsets at the interface of semi-insulating InP (100) and ALD HfO_2 were also determined. The barrier between the top of InP valence band (VB) and the bottom of Al_2O_3 conduction band (CB) is found to be 3.44 eV for p-type material and 3.53 eV for n-type. The photoemission thresholds are found to be sensitive to the annealing conditions, and blue shifts are observed after annealing. The offsets from InP valence band to the HfO_2 conduction band for the HfO_2/InP stack are found to be 3.89 eV, and we observed an increase of 60meV if the InP surface is passivated.