由於導帶附近的強費米能階釘紮效應(Fermi level pinning)，二硫化鉬(MoS2)顯示出 n型導電特性。缺乏有效的 p型摻雜阻礙了基於 p-n接面的元件應用，例如光電二極管、發光元件。過去已經提出了幾種方法來實現二硫化鉬(MoS2)中的摻雜，例如化學氣相沉積(CVD)替代摻雜、通過分子化學吸附/物理吸附或沉積薄膜的電荷轉移(charge transfer)摻雜和利用電漿的原子替代摻雜。在這些方法中，利用電漿的原子替代摻雜具有區域選擇性的優點。氮電漿的原子替代摻雜可以對二硫化鉬(MoS2)造成氮摻雜，並作為 p 型摻雜劑，但是對於單層二硫化鉬(MoS2)的氮電漿處理的相關研究進展甚微。 本篇論文利用電感耦合電漿(inductively coupled plasma)系統來進行氮電漿處理，探討不同製程參數對單層二硫化鉬(MoS2)薄膜的影響，其參數包含功率、時間、治具溫度、工作壓力及電漿源到樣品表面的距離。通過使用拉曼光譜(Raman spectroscopy)評估原始和氮摻雜的單層MoS2薄膜。在最佳條件下，A1g峰藍移約1.87 cm-1，I(E12g)/ I(A1g)的比值相對於原始的MoS2降低了約48%。與X射線光電子能譜(X-ray photoelectron spectroscopy)結果符合，紫外光電子能譜(ultraviolet photoelectron spectroscopy)研究表明，共價氮摻雜後，價帶最大值(VBM)向費米能量(Fermi energy)附近移動。 ;MoS2 show n-type conduction characteristics due to strong Fermi level pinning near the conduction band. The lack of effective p-type doping hinders the device applications based on p–n junction such as photodiodes and light-emitting devices. Several approaches have been proposed to achieve doping in MoS2, such as substitutional chemical vapor deposition (CVD) doping, charge transfer doping via molecular chemisorption/physisorption and plasma doping. Among all these methods, plasma doping has the advantage of area-selectivity. Substitutional doping of nitrogen plasma can cause nitrogen doping of molybdenum disulfide (MoS2) and act as a p-type dopant. However, little progress has been made in nitrogen plasma treatment of monolayer molybdenum disulfide (MoS2). In this study, inductively coupled plasma system was used to investigate the effect of N2 plasma treatments on monolayer MoS2. The effects of different N2 plasma treatment parameters on monolayer MoS2 were studied to optimize the covalent nitrogen doping conditions. The parameters included power, time, sample temperature, working pressure and the distance from the plasma source to the sample surface. The pristine and nitrogen-doped monolayer MoS2 films are evaluated by using Raman spectroscopy. Under optimal condition, the A1g peak blue shifted by about 1.87 cm-1, the E12g peak intensity to A1g peak intensity ratio decreased by about 48% with respect to the pristine MoS2. In accordance with the X-ray photoelectron spectroscopy results, the ultraviolet photoelectron spectroscopy investigation shows that the valence band maximum shifts closer to the Fermi energy after covalent nitrogen doping.
