掃描式穿隧顯微鏡及 X 射線光電子能譜在鐵修飾二硒化鉬在
高定向熱解石墨上之研究

自單層石墨烯問世之後，二維材料的新穎性質，使其在自旋電子學領域成為主流的研究目標之一。考慮到石墨烯缺少能隙這個事實，近來半導體二硫化鉬漸漸變得更為熱門，以其作為母材的自旋閥式磁電阻與自旋場效電晶體紛紛被提出，單層的二硫化鉬不僅擁有傳統半導體的性質，更進一步打開電子能谷(valley)這個全新自由度。單層二硫化鉬的電子自旋態擁有動量空間極化的性質，且能帶結構的能谷之間也有選擇規律，這向科學界重新介紹了過度金屬硫化物在自旋電子學領域中的重要性。然而在繼續這個系列材料的研究之前，我們必須審慎研究其與磁性金屬之間如何互相影響，以確保裝置設計上的完善。在繁多的過度金屬硫化物中，我們選取二硒化鉬作為討論的目標，其能隙較二硫化鉬要更小，且自旋在導帶與價帶能谷皆具能量選擇極化。本篇研究著重於磁性金屬鐵成長在二硒化鉬上的影響，並以高定向熱解石墨作為基板，利用掃描穿隧電子顯微鏡分析，我們發現鐵偏向聚集在二硒化鉬而非基板上，且以集簇成長的模式。掃描穿隧電子能譜分析結果顯示，鍍鐵會對二硒化鉬帶來 p 型參雜的效應。 X 射線光電子能譜研究則顯示鉬產生了新的價態，且其強度隨著鍍鐵的量線性成長，透過一些早先的研究佐證，我們有了鐵可能對鉬產生取代效應的結論，二硒化鉬的能帶結構甚至可能已經被改變，在自旋電子學裝置設計過程中應考量這個可能性。

關鍵字

二硒化鉬；二維材料；半導體；掃描式穿隧顯微鏡；掃描式穿隧能譜； X 射線光電子能譜；磁性金屬參雜

並列摘要

Novel properties of 2D materials make them one of the main stream topics in the past decade. Van der Waals materials, especially graphene, are the hottest ones. Considering the gapless band structure of graphene, transition metal dicholcogenide (TMDC) MoS2 as a semiconductor becomes popular recently. Single layer MoS2 not only possesses with semiconductor nature, but also introduces a new valley degree of freedom to the world. Relativistic spin–orbit interaction allows spin and valley degree of freedom to couple with each other. Spin state of single layer MoS2 is polarized in momentum space, and electrons in the valleys of band structure follow selection rule. This renews the importance of TMDCs in spintronics. Therefore, spin valve devices and spin FET based on MoS2 are proposed in these days. But, before further researching on these materials, we have to check the interaction between them and the magnetic metals, to ensure the consummation of design. From many kinds of TMDCs, we choose MoSe2 as a target for discussion. Its band gap is smaller than MoS2, and both conduction and valence valleys split. This study is focusing on the effects of magnetic metal Fe growth on MoSe2 on the HOPG substrate. Scanning tunneling microscopy shows that Fe aggregates on MoSe2. Scanning tunneling spectroscopy shows that Fe deposition will bring p-type doping effect to MoSe2. X-ray photonelectron spectroscopy shows that new Mo oxidation state appears after Fe deposition, and the peak intensity in XPS is linearly enhanced. Early researches provide side evidence of Mo substitution by Fe. We suggest possible changes in the bnad structue of MoSe2, which should be considered when designing spintronic devices based on MoSe2.

並列關鍵字

MoSe2 ； 2D material ； semiconductor ； scanning tunneling microscopy ； scanning tunneling spectroscopy ； X-ray photonelectron spectroscopy ； magnetic metal doping

參考文獻

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[5] Balandin, A. A. et al. Nano Letter. 8, 902–907 (2008).

[8] Wang, W. Y. et al. Nano Letters 15, 5261–5267 (2015).

國際替代計量

掃描式穿隧顯微鏡及 X 射線光電子能譜在鐵修飾二硒化鉬在高定向熱解石墨上之研究

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