| 摘要: | 黑磷烯是一種新穎二維的材料，為褶皺的六角型結構，其如同石墨烯的片層與片層之間以凡得瓦力鍵結。在2014年首次以機械剝離法由黑磷塊材中取得，命名為黑磷烯。由於石墨烯沒有直接能隙，而二硫化鉬雖有直接能隙~1.2 eV -1.8 eV，但是展現低的載子遷移率。然而，黑磷烯具有隨著厚度可調控的直接能隙（從多層~0.3 eV至單層~2.0 eV）。因此，應用於背閘極式電晶體量測其電流開關比（on-off ratio)）達到104-105，且其電洞遷移率（hold mobility）可達到1000 cm2V-1s-1，這些優異的電子特性使其可作為電子、光電以及邏輯元件等所需應用的材料。然而，此二維材料在一般環境下會與水氧反應而劣化，這將導致其本質的電傳輸性質劣化而無法實際應用。
本研究利用氟化高分子自組裝膜、氟化物旋塗以及石墨烯轉印等技術，探討不同材料披覆黑磷對其時效性之影響。透過拉曼光譜（Raman）分析氟化高分子Nafion之披覆對黑磷有160天之長期穩定的保護效果，可使黑磷表面維持本質態，減緩黑磷在空氣中的劣化，此外，在原子力顯微鏡（atomic force microscopic, AFM）分析表面形貌發現Nafion對黑磷有表面清潔效果。在電性量測中，Nafion披覆改質的黑磷電性提升，透過X-射線光電子光譜（X-ray photoelectron spectroscope, XPS）分析黑磷與Nafion的改質。然而，在探討電傳輸特性時，量測元件過程中發現Nafion仍存在黑磷快速劣化的問題，但再次利用去除Nafion之方式對黑磷表面改質，將能改善黑磷在電性分析時的穩定性，發現其電流開關比達104，且電洞遷移率達117.38 cm2V-1S-1。本研究將能提供一種有效披覆黑磷的保護方法，並維持其優異的電傳輸特性。
;Black phosphorous (BP) also known as phosphorene is a novel two-dimensional material with a hexagonal honeycomb structure, similar to graphene where the lamellar layers are bonded to each other by Van der Waals forces. In 2014, it was obtained from the bulk black phosphorus by mechanical exfoliation method. While there is no band gap in graphene and a direct bandgap of 1.2 eV -1.8 eV in monolayer molybdenum disulfide (MoS2), the BP on the other hand, has a thickness-dependent direct bandgap ( 0.3 eV for multilayers to 2.0 eV for monolayer). BP can be efficiently applied to electronic components as it has a high on-off ratio of 104-105, and carrier mobility of ~1000 cm2V-1S-1, both of which are excellent features necessitated in logic devices. However, BP has the disadvantage of being easily oxidized in ambient conditions, resulting in the deterioration of its intrinsic electrical transport properties.
In the present study, several techniques have been explored using various passivated materials to protect BP, such as fluorinated polymer self-assembly, fluoride spin coating, and transferring of graphene to BP. Raman analysis showed that the Nafion solution can provide a long-term stability protection to BP, passivate the BP surface in an essential state, and reduce environmental degradation up to 160 days. In addition, atomic force microscopy (AFM) image shows that the Nafion solution can also remove the BP surface impurities. We also explored the chemical modification of Nafion solution on BP and its effect in electrical properties. The Nafion coating is found to enhance the electrical property of BP (on-off ratio) which may be due to the strong interaction between the BP and Nafion forming a P-F bond as seen from the X-ray Photoelectron Spectroscopy (XPS). However, when measuring electrical properties of the Nafion coated on BP, the BP would still degrade quickly. However, when Nafion was selectively coated on BP surface, it was found that the BP wasn’t only improved stability, but also shown excellent electrical properties, such as on-off ratio of 104 and the hole mobility of 117.38 cm2V-1S-1. |
