Inelastic Electron Tunneling Spectroscopy of Graphene/hexagonal Boron Nitride heterostructures

Inelastic Electron Tunneling Spectroscopy (IETS) has been used for several decades as an experimental probe to access the vibrational properties of low dimensional materials. Notably, the ability to investigate these properties could be leveraged to gain further insight into the recently reported unconventional superconductivity in twisted bilayer graphene. Currently, there exists several IETS measurements on heterostructures of graphene and hexagonal Boron Nitride (hBN). These studies employed different experimental approaches such as tunneling from an atomically sharp asperity with scanning tunneling spectroscopy (STS) and planar tunneling via tunneling field effect transistors (TFETs). Importantly, the IETS results from these different experimental approaches lack agreement. To address this disparity we provide a direct comparison between IETS measurements acquired from STS and TFETs on graphene/hBN heterostructures that underwent the same fabrication processes. Our work contributes towards benchmarking IETS of two-dimensional material heterostructures and will enable future application of this technique to the study of unconventional superconductivity in twisted bilayer graphene.