Effects of Oxygen Partial Pressure on the Electronic Properties and Chemical State of MgO/SiO₂/Si(100) Thin Films

Abstract

Magnesium Oxide (MgO) thin films were deposited on SiO2/Si substrate by electron beam evaporation. The properties of MgO thin film with and without oxygen partial pressure have been investigated by X-ray photoelectron spectroscopy (XPS), Reflection Electron Energy Loss Spectroscopy (REELS), and Ultra-Violet Photoemission Spectroscopy (UPS). The XPS was used to investigate the chemical state of the film. REELS spectra revealed that MgO thin films deposited under oxygen partial pressure had band gaps of 6.07 eV. Meanwhile, the band gap for MgO thin films grown without oxygen partial pressure was 7.17 eV. The UPS results showed that the work functions of MgO thin film with and without oxygen partial pressure are 4.75 and 4.84 eV, respectively. In the MgO thin film with oxygen partial pressure, the intensity for the valence band peak at 12.16 eV decreased, but the work function remained relatively the same. Our results demonstrated that the oxygen partial pressure played a crucial role in improving the electronic properties of MgO thin films.