Porous materials are essential for a wide range of applications in energy storage, catalysis, and environmental solutions. Material fabrication methods which can tailor the porous structures in a deterministic manner are highly valuable for the development of the field. In this paper, we use ion irradiation to synthesize large-scale germanium (Ge)-based porous structures. We furthermore demonstrate the structure to consist of pores interconnected by ultra-small channels that effectively allow transport of gaseous molecules throughout the whole network. Aside qualitative assessment of the evolution of the structure, the combination of transmission electron microscopy, microbeam Rutherford backscattering spectrometry and a Ge-on-Si sample design enables the quantification of properties such as mass density and sputtering yields during the evolution of porosity. We find progression of pore formation from the surface with a constant rate with increasing dose at otherwise constant density of the porous phase. Proximity to the substrate terminates pore formation well before reaching the interface with higher doses, eventually inducing a depth-independent densification of the porous structure. Experimental evidence challenges vacancy clustering as a commonly referred-to mechanism for pore-formation. Instead, relaxation in structurally weakened, i.e. near-surface volumes of the material by micro-explosions can conclusively explain all observations. The porous germanium synthesized in our approach is considered more resilient at high temperature and strong pH conditions than polymeric and hybrid materials, indicating great potential for applications in such environments.

中文翻译：

---

通过量化自辐射过程中结构特性的演变来实现定制的纳米多孔锗


多孔材料对于能源存储、催化和环境解决方案的广泛应用至关重要。能够以确定性方式定制多孔结构的材料制造方法对于该领域的发展非常有价值。在本文中，我们利用离子辐照合成了大规模的锗（Ge）基多孔结构。我们还证明了该结构由通过超小通道互连的孔组成，这些孔有效地允许气体分子在整个网络中传输。除了对结构演变的定性评估之外，透射电子显微镜、微束卢瑟福背散射光谱法和硅基锗样品设计的结合还可以量化孔隙率演变过程中的质量密度和溅射产率等特性。我们发现，在多孔相密度恒定的情况下，随着剂量的增加，从表面开始以恒定速率形成孔。靠近基底可以在较高剂量到达界面之前很好地终止孔的形成，最终导致多孔结构的与深度无关的致密化。实验证据对空位聚集作为通常提到的孔隙形成机制提出了挑战。相反，结构弱化的松弛，即微爆炸导致的材料近表面体积的松弛可以最终解释所有观察结果。我们的方法合成的多孔锗被认为在高温和强 pH 条件下比聚合物和混合材料更具弹性，这表明在此类环境中具有巨大的应用潜力。