二維材料二硫化鈮表面結構與電性初探

Abstract

二硫化鈮是屬於金屬性二維材料中的過度金屬二硫族化物，雖然理論學家已經對於二硫化鈮有許多報導，但在奈米級的表面相關影像卻非常少，可能源自於對二硫化鈮表面掃描時要取得清晰的影像並不容易，需要有相當的掃描經驗與對掃描影像的後續處理才能取得較清晰的二硫化鈮奈米級表面。本篇實驗透過掃描穿隧式電子顯微鏡觀察二硫化鈮機械剝離前後與曝氧5到40分鐘的表面缺陷並分析以及使用掃描穿隧能譜功能量測其不同狀態下的電性變化。觀察到隨著曝氧時間增長二硫化鈮表面上的暗點和亮點缺陷有變大的趨勢，至於在費米能階附近的電阻會隨著與氣體接觸而上升，而正負偏壓下會逐漸回到如機械剝離前的狀態。

Niobium disulfide is a transition metal dichalcogenide (TMDs) in metallic two-dimensional materials. Although theorists have reported many reports on niobium disulfide, there are very few on nanoscale surface images. Since it is not easy to obtain a clear image when scanning the surface of niobium disulfide, considerable scanning experience and subsequent processing of the scanned image are required to obtain a clearer nanoscale surface of niobium disulfide.In this experiment, the surface defects on NbS2 before and after mechanical exfoliation and exposure to oxygen for 5 to 40 minutes were analyzed by STM, and analyze the electrical changes in different states by STS function. We observed that the dark spot and light spot defects on the NbS2 surface tend biger with the increase of oxygen exposure time. As for the resistance near the Fermi level, it will increase with the contact with the gas, and the positive and negative bias will return such as the state before mechanical exfoliation.