以多光子顯微術研究二維半導體之原子邊緣

Multiphoton Microscopy to Study the Atomic Edge of 2D Semiconductors

林光儀(Kuang-I Lin)

《化學》 79卷1期 (2021/03) Pp. 23-32

https://doi.org/10.6623/chem.202103_79(1).010

摘要

二維單晶過渡金屬二硫屬化物主要為具有不同邊緣原子結構的三角形薄膜，且具有半導體特性。多光子激發掃描顯微鏡可用於研究其一維原子邊緣的侷域電子能態，其位於能隙中，在量子觀點下此能態可導致光學二倍頻的大幅增強。因此二倍頻影像量測可以推斷微觀下硫的Z字形邊緣、鉬的Z字形邊緣與硫－鉬Klein邊緣（裸鉬原子從一個硫的Z字形邊緣突出）和其邊緣原子相依的共振能量。我們使用基於密度泛函理論的計算來解釋此三種邊緣態之間的能量差異。這種精確而實用的全光學技術為表徵過渡金屬二硫屬化物提供了便利和高效率的途徑。

關鍵字

過渡金屬二硫屬化物 ； 化學氣相沉積 ； 多光子顯微術 ； 二倍頻 ； 邊緣結構 ； 密度泛函理論

並列摘要

Two-dimensional (2D) single crystal transition metal dichalcogenides (TMDs) are mainly triangular thin films with different edge atomic structures, and have semiconductor characteristics. Multiphoton excitation scanning microscope can be used to study the local electronic energy state at its one-dimensional atomic edges, which is within the energy gap. From the quantum point of view, this energy state can lead to a substantial increase in optical second-harmonic generation (SHG). Microscopic S-zigzag edge, Mo-zigzag edge, S-Mo Klein edge (bare Mo atoms protruding from a S-zigzag edge) terminations and the edge-atom dependent resonance energies can therefore be deduced based on SHG-image studies. We use theoretical calculations based on density functional theory to explain the energy difference between these edge states. This precise and practical full-optical technology provides a convenient and high-throughput screening approach for characterizing TMDs.

並列關鍵字

Transition metal dichalcogenides ； Chemical vapor deposition ； Multiphoton microscopy ； Second-harmonic generation ； Edge termination ； Density functional theory