| 摘要: | 黑磷為磷的眾多同素異型體中，在熱力學上最為穩定的一種，其獨特的二維片層結構，使它有許多優異的特性，在其二維的多層晶體結構中，如同石墨烯，片層與片層之間以凡得瓦力鍵結。早期研究中以機械剝離法可以輕易地撕下奈米級片層，而少層的黑磷稱為黑磷烯。黑磷烯在不同層數的狀態下，其能隙也隨之不同，且為直接能隙，在能隙的可調控範圍大於現今任何已被確認的過渡金屬二硫化物。同時，應用於電子元件時，其電流開關比(on-off ratio)可達到105等級，且載子遷移率可達到~ 1000 cm2/Vs，兩者皆是作為邏輯元件時所需要的優異特性，在二維材料中，期待能替代矽做為新的半導體通道材料。然而，過去研究中發現黑磷在大氣下易發生氧化，少層的黑磷烯尤其明顯，這將導致其本質的電傳輸性質劣化。如何在保護黑磷不受氧化的前提下，同時保有原來在電性上優異的性質，為一重要課題。此外，目前可量化合成黑磷烯的製程仍少被研究，其材料特性也還在研究階段。
本研究探討利用液相剝離法產生少層黑磷烯，並分析其材料性質並測試穩定性。研究中使用不同的溶劑作為介質，其中1% SDS溶於去氧水之溶劑，可以獲得高的剝解產率，片層厚度之分布約為6 nm，均一性也較其他溶劑高。此外，利用石墨烯的優異阻水氧性質，製備黑磷烯與石墨烯分散溶液，使石墨烯包覆黑磷烯片層，可以減緩黑磷烯的快速劣化。因此，可藉由優化此合成方法獲得量產且高品質的黑磷烯。本研究也展示黑磷烯組裝成連續薄膜的方法，可使黑磷烯薄膜表面維持本質態，可在60天內達到保護黑磷不受氧化的影響。同時，將少層黑磷烯組成大面積之連續薄膜的製程也利於黑磷烯於未來之元件應用。
;Black phosphorus is one of the most stable allotropes of phosphorus, and its unique two-dimensional lamellar structure makes it have many excellent properties. The two-dimensional multilayer crystal structure of black phosphorus is similar to graphene, and the lamellar layer is bonded to each other by Van der Waals bonding. In early research, it is easy to tear off the nano-level black phosphorus by mechanical exfoliation process and the nano-level black phosphorus is called phosphorene. The band gap of phosphorene changes because of different numbers of its layers, and the adjustable range of band gap is greater than any of today’s transitional metal disulfide. Meanwhile, phosphorene is applied to electronic components with a high on-off ratio of 105, and carrier mobility of ~ 1000 cm2/Vs, both of which are excellent features required as logic devices. Phosphorene is a remarkable and novel two-dimensional material expected to replace silicon as the transporting channel of the semiconducting device.
However, in the past studies, black phosphorus was prone to be oxidized easily in the atmosphere and this phenomenon was obviously observed on the few layers phosphorene, which results in deterioration of its intrinsic electrical transport properties. How to protect the black phosphorus without oxidation and maintain the excellently electrical property is an important issue. In addition, the process to quantify the synthesis of phosphorene is few to be researched, while the material properties are still at the researching stage.
In this study, we obtained phosphorene by liquid phase exfoliation, and analyzed its material properties and stability. We used different solvents as exfoliation medium, and found that 1% sodium dodecyl sulfate (SDS) dissolved in deoxygenated water solvent can get a high productivity. The thickness of few layered phosphorene is about 6 nm. The uniformity in thickness of exfoliated phosphorene with SDS solvent is better than it with other solvents.
In addition, the deterioration rate of phosphorene could be restrained by encapsulating electrochemical graphene with its excellent resistance of water and oxygen. The solution was prepared by mixing the solution with dimethylformamide (DMF) as the dispersion of phosphorene and graphene. Therefore, high quality phosphorene can be obtained by optimizing this synthesis method, the production of. Our study also demonstrates a process for the assembly of the phosphorene into a continuous film which is effective in retarding the oxidation of the phosphorene. The surface of the phosphorene film can maintain the intrinsic state, so that phosphorene can be protected within 60 days from the impact of oxidation. It is attractive and has benefit to form the continuous and large area film with a few layers of phosphorene for the applications of electrical devices in the future. |
