Jangra Vikas, Kataria Satender, Lemme Max C
Chair of Electronic Devices, RWTH Aachen University, Otto-Blumenthal-Str. 25, 52074 Aachen, Germany.
AMO GmbH, Advanced Microelectronics Center Aachen, Otto-Blumenthal-Str. 25, 52074 Aachen, Germany.
ACS Appl Electron Mater. 2024 Jun 27;6(7):4883-4890. doi: 10.1021/acsaelm.4c00305. eCollection 2024 Jul 23.
Graphene has been extensively studied for a variety of electronic and optoelectronic applications. The reported contact resistance between metal and graphene, or rather its specific contact resistance ( ), ranges from a few tens of Ω μm up to a few kΩ μm. Manufacturable solutions for defining ohmic contacts to graphene remain a subject of research. Here, we report a scalable method based on laser irradiation of graphene to reduce the in nickel-contacted devices. A laser with a wavelength of = 532 nm is used to induce defects at the contact regions, which are monitored using micro-Raman spectroscopy. Physical damage is observed using atomic force and scanning electron microscopy. The transfer length method (TLM) is used to extract from back-gated graphene devices with and without laser treatment under ambient and vacuum conditions. A significant reduction in is observed in devices where the contacts are laser irradiated, which scales with the laser power. The lowest of about 250 Ω μm is obtained for the devices irradiated with a laser power of 20 mW, compared to 900 Ω μm for the untreated devices. The reduction is attributed to an increase in defect density, which leads to the formation of crystallite edges and in-plane dangling bonds that enhance the injection of charge carriers from the metal into the graphene. Our work suggests laser irradiation as a scalable technology for reduction in graphene and potentially other two-dimensional materials.
石墨烯已被广泛研究用于各种电子和光电子应用。据报道，金属与石墨烯之间的接触电阻，更确切地说是其比接触电阻（ ），范围从几十Ω·μm到几千Ω·μm。定义与石墨烯的欧姆接触的可制造解决方案仍是一个研究课题。在此，我们报告一种基于对石墨烯进行激光辐照的可扩展方法，以降低镍接触器件中的 。使用波长 = 532 nm的激光在接触区域诱导缺陷，并用显微拉曼光谱进行监测。使用原子力显微镜和扫描电子显微镜观察物理损伤。采用转移长度法（TLM）从在环境和真空条件下经过和未经过激光处理的背栅石墨烯器件中提取 。在接触区域经过激光辐照的器件中观察到 显著降低，且与激光功率成比例。对于激光功率为20 mW辐照的器件，最低 约为250 Ω·μm，而未处理器件为900 Ω·μm。这种降低归因于缺陷密度的增加，这导致形成微晶边缘和面内悬空键，从而增强了电荷载流子从金属注入到石墨烯中的能力。我们的工作表明激光辐照是一种用于降低石墨烯以及潜在地其他二维材料中 的可扩展技术。
