Pulsed laser deposition of HfO2 thin films on indium zinc oxide: Band offsets measurements

Publication date: 1 April 2017
Source:Applied Surface Science, Volume 400
Author(s): D. Craciun, V. Craciun
One of the most used dielectric films for amorphous indium zinc oxide (IZO) based thin films transistor is HfO2. The estimation of the valence band discontinuity (ΔEV) of HfO2/IZO heterostructure grown using the pulsed laser deposition technique, with In/(In+Zn)=0.79, was obtained from X-ray photoelectron spectroscopy (XPS) measurements. The binding energies of Hf 4d5, Zn 2p3 and In 3d5 core levels and valence band maxima were measured for thick pure films and for a very thin HfO2 film deposited on a thick IZO film. A value of ΔEV=1.75±0.05eV was estimated for the heterostructure. Taking into account the measured HfO2 and IZO optical bandgap values of 5.50eV and 3.10eV, respectively, a conduction band offset ΔEC=0.65±0.05eV in HfO2/IZO heterostructure was then obtained.



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