| 摘要: | 功能化與結構可控性之石墨烯比本質石墨烯帶來更多元材料特性，並有更廣的應用層面，特別是在能源轉換與前瞻半導體的領域帶來新的潛力應用。石墨烯應用於半導體領域上，需要晶圓級轉印技術方能達到高品質石墨烯。然而，過去轉印技術對大面積的完整性、潔淨度、缺陷、高分子殘留與金屬離子殘留等影響，導致半導體元件或高功率元件的應用受到限制。本研究開發並提供解決其關鍵技術，如快速且高潔淨低汙染的蝕刻法、提高大面積乾式轉印成功率、電化學輔助轉印等，所獲得石墨烯完整度與潔淨度在97%以上，0.54 ppb/cm2的金屬離子殘留。
此外，我們延續此技術，探討石墨烯引入功率半導體元件，用於降低接觸阻抗(contact resistance)，發現當使用Ti/Al/Ni/Au歐姆層時，在高溫擴散反應下，與石墨烯在GaN介面形成TiC與TiN釘狀結構(spike)的過程，透過分析於本研究揭示其反應發生的機制與歐姆電阻之間的關係，而石墨烯可幫助將歐姆電阻降低至2.57×10-6 ohm•cm2 (無石墨烯為3.08×10-5 ohm•cm2)。
在能源方面，過去研究利用異質原子改質獲得高的產氫特性，並發展為非貴金屬系的高活性觸媒，但在原子級結構的可控性與特性的研究仍缺乏，此外也鮮有新型態商用化模組的研究。本論文研究提出共摻雜石墨烯複合觸媒，透過引入順序的不同，修復石墨烯缺陷提升電性之外，還增加創造更多析氫的吡啶活性位置(pyridinic-N)，並將共摻雜石墨烯電極結合MoSx非貴金屬觸媒，得到優秀的析氫反應(Tafel slope: 42.9 mV/dec)和極低的電荷轉移電阻(2.0 ohm)，利用雙電解液可將電解水的起始反應電壓降至0.89 V以獲取最高產氫效能。此外，也發展結合光轉換促觸媒，設計整合照光與電催化之產氫模組，將催化觸媒所需的電能結合光能，達到低能耗產氫。結果顯示，光電轉換氫氣與雙電解液的產氫效率提升四倍。
;Functionalization and structural controllability of graphene offer more diverse material properties than intrinsic graphene and broader application prospects, especially in the fields of energy conversion and advanced semiconductors, where it brings new potential applications. To apply graphene in the semiconductor field, crystal wafer-level transfer technology is required to achieve high-quality graphene. However, the conventional transfer technology has been limited in terms of the integrity, cleanliness, defects, high molecular residue, and metal ion residue of large areas, which has hindered the application of semiconductor devices or high-power components. This study developed key technologies to address these issues, such as rapid and high-purity etching method with low-contamination, improving the yield rate of large-area dry transfer, and electrochemical-assisted transfer. The obtained graphene integrity and cleanliness are above 97%, with a metal ion residue of 0.54 ppb/cm². Furthermore, we extend this technology to explore the introduction of graphene into power semiconductor devices for reducing contact resistance (Rc), and find that the Ti/Al/Ni/Au ohmic layer uses a high-temperature diffusion reaction with graphene at the GaN interface to form TiC and TiN spike structures. Through analysis in this study, the mechanism of the reaction and the relationship between ohmic resistance are revealed. Graphene can help reduce the contact resistance to 2.57×10-6 ohm•cm2 (without graphene is 3.08×10-5 ohm•cm2).
In the energy applications, previous studies have focused on improving the hydrogen production characteristics of heterogeneous atoms and developing high-activity catalysts based on non-precious metal systems, but there has been a lack of research on the controllable and characteristic atomic-level structure. Here has been little research on the commercialization of new types of modules. This thesis proposes the development of a co-doped graphene composite catalyst, which not only repairs the defects in graphene to improve its electrical properties but also creates more active sites (pyridinic-N) by introducing the order in a controlled manner. The co-doped graphene electrode is then combined with the MoSx non-precious metal catalyst to achieve excellent hydrogen evolution reaction (42.9 mV/dec) and extremely low charge transfer resistence is 2.0 ohm. By using dual electrolytes to reduce the onset potential of water to 0.89 V, the highest hydrogen production efficiency can be achieved. Additionally, we also developed a system that combines photoconversion photocatalysis and designed an integrated photoelectrocatalytic hydrogen production module. This system combines the electrical energy required for the catalytic process with solar energy, achieving low-energy hydrogen production. The results show a fourfold increase in light utilization efficiency. |
