第一原理計算原子級薄過渡金屬二硫族化合物奈米緞帶摻雜過渡金屬原子

First-principles studies of atomically thin transition-metal dichalcogenide nanoribbons with transition-metal dopants

陳彥宏(Yan-Hong Chen)

指導教授 ： 鄭舜仁

國立交通大學/理學院/電子物理系所/碩士(2019年)

摘要

在這份論文中，以第一原理計算系統性地分析過渡金屬二硫族化合物(WS2) 扶手型奈米緞帶摻雜3d軌域過渡金屬原子。WS2扶手型奈米緞帶為非磁性及半導體特性的材料，此外，其能隙附近的價帶及導帶能帶，巨幅地受邊界態所影響。

計算中，將扶手型奈米緞帶中間之W原子替換為過渡金屬原子，期待能改變系統的電子結構。奈米緞帶的結構允許我們改變其寬度，使摻雜物及邊界原子的交互作用改變，此外我們也研究並調控摻雜物在系統中的濃度，觀察濃度對系統的影響。

結果顯示，Cr摻雜的扶手型奈米緞帶會維持半導體特性，而Ti及V摻雜使系統變為導體特性，Mn, Fe及Co摻雜則會使系統帶有磁性。尤其是Fe及Co摻雜，在足夠的濃度下為半金屬特性。

關鍵字

第一原理 ； 電子結構 ； 過渡金屬二硫 族化合物 ； 奈米緞帶 ； 稀磁半導體

並列摘要

In this thesis, we use the first-principles calculations to systematically explore the electronic and magnetic properties of armchair-edged TMD(WS2) nanoribbons(ANRBs) doped with 3d transition metals(TM). WS2 ANRBs are nonmagnetic and semiconducting and the valence bands and conduction bands around energy gap are greatly affected by the edge states.

In our calculations, an ANRB doped with a TM dopant at the middle and position between the side edges is shown to substantially affect the electronic property. The NR structure allows us to adjust the interaction between the dopant and edge states by manipulating the ribbon width. We also study the effects of dopant concentration of the TM doped system.

The results show that Cr-doped ANRBs remain semiconducting, whereas Ti- and V-doped systems become conducting and Mn-, Fe- and Co-doped ones are magnetic. Especially, Fe- and Co-doped cases with the sufficient dopant concentration exhibit half-metallicity.

並列關鍵字

Ab initio calculations ； electronic structure ； transition metal dichalcogenides ； nanoribbons ； dilute magnetic semiconductors

參考文獻

[31] J.D. Desai, P. Baviskar, H. K. N, H. Pathan, Quadrivalently Doped Hematite Thin Films for Solar Water Splitting, ES Energy & Environment, DOI 10.30919/esee8c208(2018).

[1] X. Xu, W. Yao, D. Xiao, T.F. Heinz, Spin and pseudospins in layered transition metal dichalcogenides, Nature Physics, 10 (2014) 343.

[2] A. Ramasubramaniam, D. Naveh, Mn-doped monolayer MoS2 An atomically thin dilute magnetic semiconductor, Physical Review B, 87 (2013) 195201.

[3] C. Zhao, C. Jin, J. Wu, W. Ji, Magnetism in molybdenum disulphide monolayer with sulfur substituted by 3d transition metals, Journal of Applied Physics, 120 (2016) 144305.

[4] W.S. Yun, S.W. Han, S.C. Hong, I.G. Kim, J.D. Lee, Thickness and strain effects on electronic structures of transition metal dichalcogenides: 2H-MX2 semiconductors (M= Mo, W; X= S, Se, Te), Physical Review B, 85 (2012) 033305.