Band Offset Determination of Atomic-Layer-Deposited Al2O3 and HfO2 on InP by Internal Photoemission and Spectroscopic Ellipsometry
Kun Xu, Oleg A. Kirillov, David J. Gundlach, Nhan V. Nguyen, Pei D. Ye, Min Xu, Lin Dong, Hong Sio
Band offsets at the interfaces of n- and p-type InP ((100) and (111)A) and atomic-layer-deposited (ALD) Al2O3 were measured with internal photoemission and spectroscopic ellipsometry. Similarly, the band offsets at the interface of semi-insulating InP (100) and ALD HfO2 were also determined. The barrier between the top of InP valence band and the bottom of Al¬2O3 conduction band 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 HfO2 conduction band for the HfO2/InP stack are found to be 3.89 eV, and we observed an increase of 60 meV if the interface is passivated.