靜電轉印二維層狀材料技術開發

Abstract

過渡金屬二硫屬化物(TMDs)是MX2類型的半導體材料，其特點包含:高載流子遷移率、在單層的時候具有直接能隙、製作成場效電晶體的時候具有極高的電流開關比；但是此類材料為了避免超出電子元件的熱預算，因此會事先長在藍寶石基板之上，再利用轉印的方式轉印到目標基板加以應用，但是現今藍寶石基板的轉印方法皆需要使用到有機聚合物支撐層，而有機聚合物並無法被完全的去除，殘存下來的有機聚合物會對材料的電性表現產生影響，因此本研究致力於發展不需要有機聚合物支撐層之轉印方法來避免掉殘留的有機聚合物對元件性能造成影響。本實驗藉由生長OTS-SAM膜在矽基板之上，來提升累積電荷的能力，以此達成純物理吸附的方式來轉印二維層狀材料至矽基板之上，此轉印過程皆無使用有機聚合物，因此可以達到乾淨的二維材料表面，由AFM圖像也可證明使用靜電轉印法之MoS2粗糙度明顯低於PMMA轉印法；另外由場效電晶體的遲滯大小可以看出，使用靜電轉印方法的遲滯明顯較低，代表靜電轉印的MoS2表面殘留物確實較少。Transition metal dichalcogenides (TMDs) are MX2-type semiconductor materials known for their high carrier mobility, direct bandgap in monolayers, and high current on/off ratio in field-effect transistors. To avoid exceeding the thermal budget of electronic devices, TMDs are typically grown on sapphire substrates and then transferred onto the target substrates using a transfer printing technique. However, current transfer methods for sapphire substrates require the use of organic polymer support layers. These organic polymers cannot be completely removed, and their residue can impact the electrical properties of the materials. Therefore, this study aims to develop a transfer method that eliminates the need for organic polymer support layers to prevent any detrimental effects on device performance.In this experiment, an octadecyltrichlorosilane self-assembled monolayer (OTS-SAM) film was grown on a silicon substrate to enhance the ability to accumulate charge. This allowed for a purely physical adsorption-based transfer of two-dimensional layered materials onto the silicon substrate, without the use of organic polymers. As a result, a clean surface of two-dimensional materials was achieved, as evidenced by AFM images that showed significantly lower roughness compared to the PMMA transfer method. Additionally, the hysteresis magnitude of the field-effect transistors indicated a significantly lower hysteresis when using the electrostatic transfer method, suggesting reduced surface residues on the transferred MoS2.