Hydrogen-free germanium (Ge)-doped diamond-like carbon (DLC) films deposited on SiO₂ substrates are studied by electron spin resonance (ESR) technique at T = 5–295 K. The Ge-free and DLC films with 1 and 2.5 at% Ge content having low cytotoxicity are investigated. A single Lorentzian ESR line resulting from exchange interaction between localized (LE) and nonlocalized electrons (NE) is observed. The spin susceptibility temperature dependence deviates from the Curie–Weiss law at T > 75 K due to Pauli contribution caused by NE. The antiferromagnetic low-temperature spin ordering in DLC films, decreasing with Ge content, is observed. The LE contribution is significant for Ge-free and DLC:1%Ge, whereas NE makes the main contribution to DLC:2.5%Ge. The LEs are related to sp ²/sp carbon-related centers, while the NEs are assigned with electrons in the sp ³ orbital. The correlation between the sp ³/sp ² ratio and the shift of g-factor for NE to lower values with Ge doping is established. The Korringa relaxation model is provided for the ESR linewidth temperature dependence. The higher density of LE states on Fermi energy level caused by Ge doping of DLC films is proposed.

中文翻译：

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无氢掺锗类金刚石碳膜的电子自旋共振研究

通过电子自旋共振 (ESR) 技术在T  = 5–295 K研究了沉积在 SiO ₂基板上的无氢锗 (Ge) 掺杂类金刚石碳 (DLC) 薄膜。无锗和 DLC 薄膜具有 1 和研究了具有低细胞毒性的 2.5 at% Ge 含量。观察到由局部 (LE) 和非局部电子 (NE) 之间的交换相互作用产生的单个洛伦兹 ESR 线。自旋磁化率温度依赖性偏离T处的居里-魏斯定律 > 75 K 由于 NE 引起的 Pauli 贡献。观察到 DLC 薄膜中的反铁磁低温自旋有序性随 Ge 含量的增加而降低。LE 贡献对于 Ge-free 和 DLC:1%Ge 是显着的，而 NE 对 DLC:2.5%Ge 做出主要贡献。LE 与sp ² / sp碳相关中心相关，而 NE 分配有sp ³轨道中的电子。sp ³ / sp ²比率与g偏移之间的相关性-确定了 NE 降低 Ge 掺杂值的因素。为 ESR 线宽温度依赖性提供了 Korringa 弛豫模型。提出了由 DLC 薄膜的 Ge 掺杂引起的费米能级上更高的 LE 态密度。