Wang Yi, Ren Jie
Center for Phononics and Thermal Energy Science, China-EU Joint Center for Nanophononics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Sciences and Engineering, Tongji University, Shanghai 200092, China.
Phys Chem Chem Phys. 2020 Feb 28;22(8):4481-4489. doi: 10.1039/c9cp05280a. Epub 2020 Feb 17.
Hafnium oxides have been widely applied in modern electronic and photonic devices as a thin film layer due to their wide electronic band gap and high dielectric constant. Here, based on a high-throughput evolutionary structure search, we explore a two-dimensional HfO zoo and identify six thermodynamic stable phases of the atomic thin monolayer. We confirm their mechanical and dynamical stabilities by calculating the elastic tensors and phonon dispersions as well as by carrying out ab initio molecular dynamic simulations at finite temperatures. In particular, we investigate the electronic and optical properties of those stable two-dimensional HfO structures. In spite of their diverse different structures, the two-dimensional HfO phases all have wide electronic band gaps and high dielectric constants, all indicating large capacitances due to the small thickness of the monolayer structures. Our findings demonstrate that atomic thin two-dimensional HfO could be a potential supercapacitor and dielectric layer for advanced nanoscale optoelectronic devices.
由于具有宽电子带隙和高介电常数，氧化铪作为薄膜层已被广泛应用于现代电子和光子器件中。在此，基于高通量演化结构搜索，我们探索了二维氧化铪体系，并确定了原子级薄单层的六个热力学稳定相。我们通过计算弹性张量和声子色散，以及在有限温度下进行从头算分子动力学模拟，证实了它们的力学和动力学稳定性。特别地，我们研究了这些稳定的二维氧化铪结构的电子和光学性质。尽管它们的结构各不相同，但二维氧化铪相都具有宽电子带隙和高介电常数，这都表明由于单层结构厚度小而具有大电容。我们的研究结果表明，原子级薄的二维氧化铪可能是用于先进纳米级光电器件的潜在超级电容器和介电层。
