In the electron energy loss spectra for amorphous, atomic layer deposited (ALD) Al2O3 film, a peak at 6.4 eV was observed. First principle quantum chemical simulation shows that it relates to excitation of neutral oxygen vacancy in Al2O3. The 2.91 eV luminescence excited in a band near 6.0 eV in amorphous Al2O3 is similar to that in bulk crystals which is associated with neutral oxygen vacancy. Thus, the amorphous ALD Al2O3 film is oxygen deficient and the oxygen vacancy parameters are similar in crystalline and amorphous Al2O3.

Electronic structure of oxygen vacancies in Ta₂O₅ have been studied theoretically by first-principles calculations and experimentally by x-ray photoelectron spectroscopy. Calculations of δ-Ta₂O₅ were performed using density functional theory within gradient-corrected approximation with the +U approach. Results indicate that the oxygen vacancy causes a defect level in the energy gap at 1.2 eV above the top of the valence band. To produce oxygen vacancies, amorphous films of Ta₂O₅ were bombarded with Ar⁺ ions. XPS results indicate that the Ar-ion bombardment leads to the generation of the oxygen vacancies in Ta₂O₅ that characterize the peak at 2 eV above the valence band. The calculated spectrum of crystalline δ-Ta₂O₅ demonstrates qualitative correspondence with the XPS spectrum of the amorphous Ta₂O₅ film after Ar-ion bombardment.

Al₂O₃ films 150 Å thick are deposited on silicon by the ALD technique, and their x-ray (XPS) and ultraviolet (UPS) photoelectron spectra of the valence band are investigated. The electronic band structure of corundum (α-Al₂O₃) is calculated by the ab initio density functional method and compared with experimental results. The α-Al₂O₃ valence band consists of two subbands separated with an ionic gap. The lower band is mainly formed by oxygen 2s states. The upper band is formed by oxygen 2p states with a contribution of aluminum 3s and 3p states. A strong anisotropy of the effective mass is observed for holes: m_h⊥^* ≈ 6.3m₀ and m_h‖^* ≈ 0.36m₀. The effective electron mass is independent of the direction m_e‖^* ≈ m_e⊥^* ≈ 0.4m₀.

The atomic structure of amorphous and crystalline hafnium oxide $\left(\mathrm{Hf}{\mathrm{O}}_2\right)$ films was examined using x-ray diffractometry and Hf edge x-ray absorption spectroscopy. According to the x-ray photoelectron spectroscopy and band data calculated by the density functional method, we found that the valence band of $\mathrm{Hf}{\mathrm{O}}_2$ consists of three subbands separated by ionic gaps. The upper subband is formed by O $2p$ , Hf $4f$ , and Hf $5d$ states; the intermediate subband is formed by O $2s$ and Hf $4f$ states, whereas the lower narrow subband is mainly formed by Hf $5p$ states. The energy gap of amorphous $\mathrm{Hf}{\mathrm{O}}_2$ is $5.7\mathrm{eV}$ as determined by electron energy loss spectroscopy. The band calculation results indicate the existence of light $\left(0.3m_0\right)$ and heavy $\left(8.3m_0\right)$ holes in the $\mathrm{Hf}{\mathrm{O}}_2$ film and the effective mass of electron lies in the interval of $0.7m_0–2.0m_0$ .