Chemical modification of diamond surfaces generates a negative electron affinity (NEA), which shows great potential in realizing electron emission. In this study, zirconium (Zr) termination on clean and oxidized diamond (100) surfaces is theoretically proposed by using the structure prediction method, and electronic properties of these predicted surfaces are investigated by first-principles calculations. On the oxidized surfaces, the adsorption energy at 0.25 monolayer (ML) Zr coverage reaches a high value of −10.42 eV, further confirmed by the largest integrated crystal orbital Hamiltonian population value of 6.61 eV. For clean and oxidized diamond (100) surfaces, the largest NEA values at 0.25 ML Zr coverage are −3.75 eV and −3.45 eV, respectively. The dynamic stability of these surface structures is demonstrated by calculating phonon dispersion curves. Furthermore, ab initio molecular dynamics simulations confirm the high thermal stability of the oxidized diamond surface. Therefore, these results indicate that Zr-terminated diamond (100) surfaces possess good thermal stability and higher NEA, making them promising candidate materials for electron emission applications.

中文翻译：

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具有良好负电子亲和力和表面稳定性的锆封端金刚石 (100) 表面的第一性原理研究

金刚石表面的化学修饰产生负电子亲和力（NEA），在实现电子发射方面显示出巨大的潜力。在这项研究中，利用结构预测方法从理论上提出了清洁和氧化金刚石（100）表面上的锆（Zr）端接，并通过第一性原理计算研究了这些预测表面的电子特性。在氧化表面上，0.25单层（ML）Zr覆盖度处的吸附能达到-10.42 eV的高值，6.61 eV的最大积分晶体轨道哈密顿布居值进一步证实了这一点。对于清洁和氧化的金刚石 (100) 表面，0.25 ML Zr 覆盖率下的最大 NEA 值分别为 -3.75 eV 和 -3.45 eV。这些表面结构的动态稳定性通过计算声子色散曲线来证明。此外，从头算分子动力学模拟证实了氧化金刚石表面的高热稳定性。因此，这些结果表明Zr封端金刚石（100）表面具有良好的热稳定性和较高的NEA，使其成为电子发射应用的有希望的候选材料。