A recent research paper by Professor Eric Pop, Asir Intisar Khan, Akash Ramdas, Emily Lindgren, Hyun-Mi Kim, Byoungjun Won, Xiangjin Wu, Professor Krishna Saraswat, Ching-Tzu Chen, Yuri Suzuki, Felipe H. da Jornada, and Il-Kwon Oh was published January 2, 2025 in Science.

ABSTRACT The electrical resistivity of conventional metals such as copper is known to increase in thin films as a result of electron-surface scattering, thus limiting the performance of metals in nanoscale electronics. Here, we find an unusual reduction of resistivity with decreasing film thickness in niobium phosphide (NbP) semimetal deposited at relatively low temperatures of 400°C. In films thinner than 5 nanometers, the room temperature resistivity (~34 microhm centimeters for 1.5-nanometer-thick NbP) is up to six times lower than the resistivity of our bulk NbP films, and lower than conventional metals at similar thickness (typically about 100 microhm centimeters). The NbP films are not crystalline but display local nanocrystalline, short-range order within an amorphous matrix. Our analysis suggests that the lower effective resistivity is caused by conduction through surface channels, together with high surface carrier density and sufficiently good mobility as the film thickness is reduced. These results and the fundamental insights obtained here could enable ultrathin, low-resistivity wires for nanoelectronics beyond the limitations of conventional metals.

DOI: https://doi.org/10.1126/science.adq7096