To enhance the morphological stability of NiGe, a material of interest as a source drain-contact in Ge-based field effect transistors, Ta or W, is added as either an interlayer or a capping layer. The efficacy of this Ta or W addition is evaluated with pure NiGe as a reference. While interlayers increase the NiGe formation temperature, capping layers do not retard the NiGe formation. Regardless of the initial position of Ta or W, the morphological stability of NiGe against agglomeration can be improved by up to 100 °C. The improved thermal stability can be ascribed to an inhibited surface diffusion, owing to Ta or W being located on top of NiGe after annealing, as confirmed by means of transmission electron microscopy, Rutherford backscattering spectrometry, and atom probe tomography. The latter also shows a 0.3 at. % solubility of Ta in NiGe at 450 °C, while no such incorporation of W is detectable.

中文翻译：

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添加钽和钨提高锗化镍的形态稳定性

为了增强 NiGe 的形态稳定性，添加了一种感兴趣的材料作为 Ge 基场效应晶体管中的源漏接触材料，Ta 或 W，作为中间层或覆盖层。这种 Ta 或 W 添加的功效以纯 NiGe 作为参考进行评估。虽然夹层会增加 NiGe 的形成温度，但覆盖层不会阻碍 NiGe 的形成。无论 Ta 或 W 的初始位置如何，NiGe 抗团聚的形态稳定性最高可提高 100 °C。正如通过透射电子显微镜、卢瑟福背散射光谱法和原子探针断层扫描所证实的那样，热稳定性的提高可归因于表面扩散受到抑制，因为退火后 Ta 或 W 位于 NiGe 的顶部。后者也显示了 0.3 at。