| 摘要: | 為了生產高品質的電晶體通道層二硫化鉬，已經提出了多種製備方法，例如機械剝離、物理氣相沉積、化學氣相沉積、原子層沉積和有機金屬化學氣相沉積等。其中，化學氣相沉積法合成的二硫化鉬薄膜具有較好的品質和電傳輸特性，因此被廣泛使用。雖然化學氣相沉積法可以生產出面積較大且高品質的二硫化鉬薄膜，但其中許多因素可能導致薄膜品質不佳，例如原子級缺陷、晶界和雜質摻入等因素，進而導致光學和電學性質大幅下降。
相較於合成於結晶性藍寶石基板，直接合成二硫化鉬於非晶基板(如氧化矽或氮化矽)雖有利於整合後段相容製程，但要達到高結晶合成品質仍存在瓶頸。本研究通過調節成長系統的參數，整理出各種環境參數的變化和影響，並實現了大面積高結晶品質的單晶二硫化鉬的生長。研究結果顯示，在成長部分由主導的溫度、壓力、流速等主要條件下若在適當區間可初步成長出二硫化鉬奈米顆粒，再搭配前驅物比例及細部調整則可使單晶尺寸達到10 µm以上，同時其拉曼分析結果顯示為單層，透過光致發光分析其結晶品質也可以得到 58 meV的高結晶品質。
此外，本研究也比較了不同的基板表面處理法對於生長時的成核與摻雜問題，並獲得以溶劑丙酮超音波震清法處理，可達到高潔淨度，且同時可使成核密度由未處理前的10 site/µm2降低至處理後為0.04 site/µm2。金陣列點位試驗中也成功解決了成核無序的限制，透過較低的介面能使得二硫化鉬趨向在陣列點位周圍異質成核，同時抑制均質成核的發生，達到選擇性成核的效果。
;Various preparation methods have been proposed to produce high-quality molybdenum disulfide (MoS2) transistor channel layers, such as mechanical exfoliation, physical vapor deposition, chemical vapor deposition, molecular layer deposition, and metal-organic chemical vapor deposition. Among them, MoS2 thin films synthesized by chemical vapor deposition (CVD) exhibit better quality and electrical transport properties, making them widely used. Although the CVD method can produce large-area and high-quality MoS2 thin films, several factors can lead to poor film quality, such as atomic-scale defects, grain boundaries, and impurity doping, resulting in significant degradation of optical and electrical properties.
Compared to synthesizing MoS2 on crystalline sapphire substrates, direct synthesis on amorphous substrates(such as silicon oxide or silicon nitride) is advantageous for integrating into the back-end of line processes. However, there are still bottlenecks in achieving high-quality crystalline synthesis. In this study, by adjusting the parameters of the growth system, the variations and effects of various parameters were organized, leading to the achievement of large-area, high-crystallinity single-crystal MoS2 growth. The research results indicate that under the main conditions dominated by temperature, pressure, flow rate, etc., if within an appropriate range, MoS2 nanoparticles can be preliminarily grown. By combining precursor proportions and fine adjustments, single-crystal sizes can reach 10 µm or more. Raman analysis confirms the flake is single-layer, and photoluminescence analysis reveals a high crystalline quality of 58 meV.
Additionally, this study compared different substrate surface treatment methods to solve the nucleation and doping issues during growth. It was found that the use of the solvent acetone with an ultrasonic cleaning method can achieve high cleanliness and reduced the nucleation density from 10 sites/µm2 to 0.04 sites/µm2 after acetone clean treatment. The gold array test successfully addressed the limitations of nucleation disorder. By employing lower interfacial energy, MoS2 tended to nucleate heterogeneously around the array points, while suppressing homogeneous nucleation, achieving a selective nucleation effect. |
