A detailed analysis of the band alignment between molecular beam deposited amorphous HfO2 and GaAs is reported. The conduction band offset, measured by internal photoemission (IPE), is 1.9±0.2eV. The valence band offset (VBO) is probed by x-ray photoelectron spectroscopy (XPS). The accurate determination of the VBO requires a careful evaluation of differential charging phenomena and consequently a proper correction of the energy scale. The measured VBO value is 2.1±0.1eV. Since the HfO2 gap is 5.6eV, as detected by photoconductivity analysis, the results obtained by IPE and XPS are in excellent agreement.
American Institute of Physics
5 Nov 2007
Volume: 91 Issue: 19 Pages: 192902
Applied Physics Letters