Structures and electronic properties of four crystal GeO₂ and two rare-earth element oxides La₂O₃ and CeO₂

This paper presents a first principles calculation of the structure and electronic properties of four crystal GeO₂ structures and two rare-earth element oxides CeO₂ and La₂O₃. A GGA was used to optimize structures and calculate band structure and density of states (DOS). It is found that La₂O₃ has the largest band gap (4.19 eV) among all the six structures, which also means it is the best insulator among them. When it comes to four crystal GeO₂ structures, which were calculated to make a comparison with two insulators CeO₂ and La₂O₃, we found the q-GeO₂ and b-GeO ₂ are more likely to work as the dielectrics used in MOS devices than the other two crystalline forms. Three of the four GeO₂ forms have larger band gap than that of CeO₂ (2.09 eV), which indicates CeO ₂ is not a wise choice when deposited directly on the surface of Ge substrate.