dc.description.abstract | 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. | en_US |