Division of Chemical and Biomolecular Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798, Singapore.
Phys Chem Chem Phys. 2013 Apr 28;15(16):5927-35. doi: 10.1039/c3cp43530j. Epub 2013 Mar 14.
We report a systematic study on the surface passivation and strain effects on the electronic properties of hydrogenated germanium nanowires (H-GeNWs) with different growth orientations and diameters using density functional theory calculations. We show that increasing the coverage percentage of halogen passivations--fluorine (F) and chlorine (Cl) in particular--reduces the band gap of the GeNWs drastically but not linearly, depending on the chemical environment of the passivation sites. Moreover, we find that in general, applying strain--either compression or tensile--can only induce a decreased band gap in GeNWs but exception is found in <110> GeNWs: an increased band gap can be induced which is determined to be related to their surface structures. The current work reveals that electronic response upon structural changes caused by external factors is more sensitive in <110> GeNWs than in <100> GeNWs, suggesting that GeNWs with selected growth orientation can be applied in specialized applications that require different degrees of sensitivity or robustness.
我们使用密度泛函理论计算对具有不同生长方向和直径的氢化锗纳米线（H-GeNWs）的表面钝化和应变对电子性质的影响进行了系统研究。我们表明，增加卤化物钝化（尤其是氟（F）和氯（Cl））的覆盖率百分比会大大降低 GeNWs 的带隙，但不是线性的，这取决于钝化位点的化学环境。此外，我们发现，一般来说，施加应变——无论是压缩还是拉伸——只能在 GeNWs 中引起带隙减小，但在<110>GeNWs 中存在例外：可以诱导带隙增加，这与它们的表面结构有关。目前的工作表明，由外部因素引起的结构变化所导致的电子响应在<110>GeNWs 中比在<100>GeNWs 中更为敏感，这表明具有选定生长方向的 GeNWs 可以应用于需要不同程度的灵敏度或鲁棒性的特殊应用。
