Graphene-coated conductive probes with enhanced sensitivity for nanoIR spectroscopy

Yu-Jiao Xia-Hou, Xu-Cheng Li, En-Ming You, Hong-Peng He, Jun Yi, Jun-Rong Zheng, Hai-Long Wang, Hai-Xin Lin and Zhong-Qun Tian

Nano Research 16, 11326 (2023)
Nano-infrared (nanoIR) probes play a crucial role as nano-mechanical sensors and antennas for light absorption and emission, and their testing performance is critically dependent on their optical properties and structural stability. Graphene-coated dielectric probes are highly attractive for enhancing light–matter interactions and integrating IR photonics, providing a broadband optical response and strong electromagnetic field. However, achieving continuous single-layer graphene growth on non-planar and non-single crystalline dielectrics is a significant challenge due to the low surface energy of the dielectric and the large difference in size between the probe tip, cantilever, and substrate. Herein, we present a novel method for the growth of high-quality and continuous graphene with good conductivity on non-planar and amorphous dielectric probe surfaces using manganese oxide powder-assisted short time heating chemical vapor deposition. The resulting graphene-coated dielectric probes exhibit an average IR reflectance of only 5% in the mid-IR band, significantly outperforming probes without continuous graphene coating. Such probes can not only effectively transduce the local photothermal sample expansion caused by the absorption of IR laser pulses, but also effectively scatter near-field light, which is 25 times stronger than the commercial metal-coated probes, and have advantages in the application of nanoIR sensing based on atomic force microscope-based infrared (AFM-IR) spectroscopy and infrared scattering scanning near field optical microscopy (IR s-SNOM) principles. Furthermore, our graphene growth method provides a solution for growing high-quality graphene on the surfaces of non-planar dielectric materials required for integrated circuits and other fields.