Fischer Miriam, Maity Sayantan, Kuntumalla Mohan Kumar, Hoffman Alon
Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 320003, Israel.
J Chem Phys. 2024 Oct 14;161(14). doi: 10.1063/5.0235233.
Nitrogen-rich ultra-thin (1-2 nm thick) layers in diamond produced by high-temperature nitrogen ion (N2+) implantation at low N2+ energies studied by in situ x-ray photoelectron spectroscopy are reported. Nitrogen bonding at the subsurface region and its thermal stability, as well as structural defects in polycrystalline diamond (PCD) implanted with 200, 500, and 800 eV N2+ at room temperature (RT) and 600 °C at an ion dose of 4.5 × 1014 ions/cm2, are investigated. Implantation at RT leads to nitrogen bonding at interstitial and substitutional sites in the diamond lattice, which is associated with the C-N/C=N bond, lower intensity of the C≡N (nitrile-like) component associated with nitrogen bonding with carbon defects, and quaternary nitrogen. The relative composition of these chemical states varies with implantation energy, temperature, and post-implantation annealing temperature. Upon annealing the RT implanted layers above 500-600 °C, the interstitial nitrogen converts to substitutional nitrogen. This process competes with nitrogen desorption. The thermal stability of nitrogen increases with implantation energy. Implantation at 600 °C at 800 eV resulted in a significantly lower concentration of nitrile-like bonds and a lower density of structural defects compared to RT implantation at the same energy. These effects are associated with dynamic annealing, which becomes more significant at higher implantation energies. Upon high-temperature implantation, nitrogen mostly populates directly substitutional sites. Nitrogen implantation at low energy and high temperature may be a viable way to nitride diamond surfaces with reduced density of defects where nitrogen is selectively bonded to substitutional sites. Finally, a comparison between nitrogen implantation into PCD and Diamond (100) [Di(100)] surfaces is presented.
报道了通过原位X射线光电子能谱研究在低N2+能量下高温氮离子（N2+）注入金刚石中产生的富氮超薄（1-2纳米厚）层。研究了在室温（RT）和600°C下以4.5×1014离子/cm2的离子剂量注入200、500和800 eV N2+的多晶金刚石（PCD）中次表面区域的氮键合及其热稳定性以及结构缺陷。室温下注入导致金刚石晶格中间隙和替代位置的氮键合，这与C-N/C=N键、与碳缺陷处氮键合相关的C≡N（腈类）组分强度降低以及季氮有关。这些化学状态的相对组成随注入能量、温度和注入后退火温度而变化。将室温注入的层在500-600°C以上退火时，间隙氮会转变为替代氮。这个过程与氮解吸相互竞争。氮的热稳定性随注入能量增加。与相同能量下的室温注入相比，800 eV、600°C下的注入导致腈类键的浓度显著降低和结构缺陷密度降低。这些效应与动态退火有关，动态退火在较高注入能量下变得更显著。高温注入时，氮大多直接占据替代位置。低能量和高温下的氮注入可能是一种使金刚石表面氮化且缺陷密度降低的可行方法，其中氮选择性地键合到替代位置。最后，给出了PCD和金刚石（100）[Di(100)]表面氮注入的比较。
