Structural and electrical properties of CeO2 monolayers using first-principles calculations

We systematically investigate the structural, electronic properties of bulk CeO2, its H-phase and T-phase monolayers, studied using first-principles calculations based on density functional theory (DFT). The calculated electronic bandgap is 2.02 eV, 0.86 eV and 2.52 eV for CeO2 bulk, H-phase and T-phase, respectively. Here, the bandgap is tuned by applying triaxial tensile strain up to 28%. Using strain engineering, the bandgap further increases and behaves as a metal at about 28% for the bulk as well as its monolayers. It is found that for bulk CeO2, initially, the bandgap increases for strains up to 16% and then decreases. Similarly, for H-phase the bandgap increases initially at 4% strain and then decreases. Whereas, for T-phase, on applying strain the band gap decreases. Here, the bandgap is in visible range due to that it will be used in optoelectronic devices such as solar cells and LEDs. The result also shows that the CeO2 nanostructures have diverse electronic properties, tunable by strain engineering and have wide applications in nanoelectronics and nanodevices.