Chen Bo-Yu, Chen Bo-Wei, Uen Wu-Yih, Chen Chi, Chuang Chiashain, Tsai Dung-Sheng
Department of Electronic Engineering, Chung Yuan Christian University, Taoyuan, 32023, Taiwan.
Department of Physics, National Taiwan University, Taipei, 10617, Taiwan.
Nanotechnology. 2024 Feb 28;35(20). doi: 10.1088/1361-6528/ad2381.
A transfer-free graphene with high magnetoresistance (MR) and air stability has been synthesized using nickel-catalyzed atmospheric pressure chemical vapor deposition. The Raman spectrum and Raman mapping reveal the monolayer structure of the transfer-free graphene, which has low defect density, high uniformity, and high coverage (>90%). The temperature-dependent (from 5 to 300 K) current-voltage () and resistance measurements are performed, showing the semiconductor properties of the transfer-free graphene. Moreover, the MR of the transfer-free graphene has been measured over a wide temperature range (5-300 K) under a magnetic field of 0 to 1 T. As a result of the Lorentz force dominating above 30 K, the transfer-free graphene exhibits positive MR values, reaching ∼8.7% at 300 K under a magnetic field (1 Tesla). On the other hand, MR values are negative below 30 K due to the predominance of the weak localization effect. Furthermore, the temperature-dependent MR values of transfer-free graphene are almost identical with and without a vacuum annealing process, indicating that there are low density of defects and impurities after graphene fabrication processes so as to apply in air-stable sensor applications. This study opens avenues to develop 2D nanomaterial-based sensors for commercial applications in future devices.
利用镍催化常压化学气相沉积法合成了一种具有高磁阻（MR）和空气稳定性的免转移石墨烯。拉曼光谱和拉曼映射揭示了免转移石墨烯的单层结构，其具有低缺陷密度、高均匀性和高覆盖率（>90%）。进行了温度依赖性（5至300 K）电流-电压（）和电阻测量，显示了免转移石墨烯的半导体特性。此外，在0至1 T的磁场下，在宽温度范围（5-300 K）内测量了免转移石墨烯的磁阻。由于在30 K以上洛伦兹力占主导，免转移石墨烯呈现正磁阻值，在300 K、1特斯拉磁场下达到约8.7%。另一方面，由于弱局域化效应占主导，在30 K以下磁阻值为负。此外，有无真空退火过程时，免转移石墨烯的温度依赖性磁阻值几乎相同，表明在石墨烯制备过程后缺陷和杂质密度较低，从而可应用于空气稳定的传感器应用。本研究为未来器件中基于二维纳米材料的商业应用传感器开发开辟了道路。
