As semiconductor fabrication reaches the nanoscale, SiO₂ gate dielectrics suffer from quantum tunneling that limits device performance; hafnium oxide (HfO₂), with a higher dielectric constant, is therefore a leading high-k candidate. Here we combine density functional theory (DFT) and ultraviolet photoelectron spectroscopy (UPS) to investigate the electronic band structure of monoclinic HfO₂. Bulk and surface models were constructed to assess the effect of a Hubbard U correction on the band gap and to compute the work function and ionization potential. With U = 6.0 eV the calculated band gap deviates from literature by 13.86%; the computed work function and ionization potential are 5.69 eV and 5.92 eV, respectively. UPS measurements (under varied bias) yield a work function of 4.33 eV and an ionization potential of 5.82 eV. These results supply crucial surface electronic-structure data for HfO₂ and support the effectiveness of combined DFT–UPS analysis.

Hafnium oxide,Ultraviolet photoelectron spectroscopy,density functional theory (DFT)