二硒化錸表面鍍鐵原子致形貌及電性變化

Abstract

二硒化錸(ReSe2)為過渡金屬二硫族化物(TMDs)的一員，過往的研究顯示TMDs材料不可避免地會有原子級的缺陷產生，於是近期大家更關注於缺陷工程(Defect Engineering)上，試圖刻意控制缺陷的產生，來達到符合我們所需的材料特性。本實驗室透過超高真空系統的建立，確保欲研究的材料表面不受其他雜質吸附，並使用掃描式穿隧顯微鏡(Scanning tunneling microscope, STM)及掃描穿隧能譜 (Scanning tunneling spectroscopy, STS)進行原子級的表面與缺陷量測。我們利用機械剝離法並搭配使用電子束蒸鍍槍，觀察二硒化錸原始表面特徵、晶格結構、機械剝離後表面缺陷及鐵原子在其表面的缺陷樣式，並量測表面態電子特性，來分析表面缺陷型態和區域大小，對材料的物理特性所造成的影響。其中更發現在表面鍍鐵原子會使電性有類似於非揮發性電阻開關(Non-volatile resistive switching)，又稱作憶阻器效應(memristor effect)的現象，顯示了鐵原子在二硒化錸表面有可能因電壓的變換而影響整體排列結構的可能。Rhenium diselenide (ReSe2) is a member of transition metal dichalcogenides (TMDs). Previous studies have shown that TMDs materials inevitably have atomic-level defects, so people have paid more attention to defect engineering recently, trying to deliberately control the generation of defects to achieve the material properties we need. Through the establishment of an ultra-high vacuum(UHV) system, we ensure that the surface of the material is not adsorbed by other impurities, and use STM and STS to measure the surface and defects at the atomic level.We use the mechanical exfoliation(Fresh) and electron beam evaporation gun to observe the original surface(Non-Fresh), lattice structure, surface defects after Fresh and the defect pattern of iron atoms on the surface of ReSe2, and measure the electronic properties of the surface state in order to analyze the impact of the surface defect type and area size on the physical properties of the material.Among them, it is found that plating iron atoms on the surface will cause electrical properties similar to non-volatile resistive switching (Non-volatile resistive switching), which shows that iron atoms on the surface of ReSe2 may affect the overall structures.