Tunneling Spectroscopy of Two-Dimensional Materials based on Via Contacts

We study how electrons transfer between normal metal contacts embedded in hexagonal boron nitride (hBN) and two-dimensional materials with various interface transparency in mesoscopic devices based on ver-tical interconnect access (via) method [1]. We use two target materials in different categories, NbSe2 and monolayer graphene, to demonstrate this planar tunneling method in superconducting and in semiconducting/insulating regimes, respectively. The advantage of precisely controlling the tunnel area size and barrier thickness is key to obtaining high-quality tunneling spectra. This type of via tunneling technique is applicable toa large variety of materials, offering a competitive path to probing materials and interface properties under ultra-low temperature and high magnetic fields otherwise inaccessible with other experimental tools.

[1] E. J. Telford et al, Nano Letters 18, 1416 (2018)