Conduction band offset of HfO2 on GaAs

Abstract

A detailed analysis of the band alignment between molecular beam deposited amorphous $\mathrm{Hf}{\mathrm{O}}_2$ and GaAs is reported. The conduction band offset, measured by internal photoemission (IPE), is $1.9\pm 0.2\mathrm{eV}$ . 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 $2.1\pm 0.1\mathrm{eV}$ . Since the $\mathrm{Hf}{\mathrm{O}}_2$ gap is $5.6\mathrm{eV}$ , as detected by photoconductivity analysis, the results obtained by IPE and XPS are in excellent agreement.