Multi-Modal Atomic Force Microscopy Reveals Strain-Induced Modulation of Surface Electronics in Thin Mo₂C Crystals

Transition metal carbides (TMCs) in thin form exhibit an attractive combination of physical properties, making them suitable for next-generation applications ranging from energy storage to electromagnetic shielding. However, realizing the potential of thin TMCs for many applications requires a fundamental understanding of how strain affects their surface electronic properties.

Here, we present a multi-modal atomic force microscopy (AFM) study on thin crystals of molybdenum carbide (Mo₂C), a representative TMC, grown via chemical vapor deposition (CVD). Mo₂C crystals featuring “rippled” regions constitute an ideal testbed for studying the effects of strain on surface electronics. In particular, high-resolution imaging and electronic spectroscopy via conductive atomic force microscopy (C-AFM) show that tensile strain leads to an enhancement of local conductivity on rippled regions. Complementary measurements of local work function via Kelvin probe force microscopy (KPFM) shed light on the physical mechanisms leading to strain-induced modulation of electronic properties in this emerging class of materials.