Orientation Dependent Resistivity Scaling in Mesoscopic NbP Crystals

TL;DR

This study investigates how the electrical resistivity of anisotropic NbP crystals varies with orientation at mesoscopic scales, combining experimental measurements and theoretical modeling to assess their potential as future interconnect materials.

Contribution

It introduces a resistivity scaling methodology for anisotropic semimetals like NbP, linking experimental data with Fermi surface theory for interconnect applications.

Findings

Resistivity depends on crystalline orientation in NbP.

Theoretical model correlates Fermi surface features with resistivity.

Method enables evaluation of anisotropic materials for nanoelectronics.

Abstract

The scaling of Si transistor technology has resulted in a remarkable improvement in the performance of integrated circuits over the last decades. However, scaled transistors also require reduced electrical interconnect dimensions, which lead to greater losses and power dissipation at circuit level. This is mainly caused by enhanced surface scattering of charge carriers in copper interconnect wires at dimensions below 30 nm. A promising approach to mitigate this issue is to use directional conductors, i.e. materials with anisotropic Fermi surface, where proper alignment of crystalline orientation and transport direction can minimize surface scattering. In this work, we perform a resistivity scaling study of the anisotropic semimetal NbP as a function of crystalline orientation. We use here focused ion beam to pattern and scale down NbP crystallites to dimensions comparable to the electron scattering length at cryogenic temperatures. The experimental transport properties are correlated with the Fermi surface characteristics through a theoretical model, thus identifying the physical mechanisms that influence the resistivity scaling of anisotropic conductors. Our methodology provides an effective approach for early evaluation of anisotropic materials as future ultra-scalable interconnects, even when they are unavailable as epitaxial films.