Hot carriers in plasmonic nitrides published in J. Opt.
Transition metal nitrides (TMNs) have a long history in applications such as hard coatings because of their exceptional mechanical and thermal properties, and have recently gained attention as refractory (high-temperature) plasmonic materials. So far, little is known about the dynamics of energetic ‘hot’ carriers generated by plasmon decay in these promising new class of materials for nano-scale light capture. In this paper, we present a comprehensive study of the plasmonic response, hot carrier generation and their subsequent transport in nitrides of group IV, V, and VI transition metals using ab initio methods, i.e. fully from first principles with no experimental input or fit parameters.
We find that these TMNs stack up quite well against noble metals like gold and silver, the conventional plasmonic metals, not only for their plasmonic response but also for their hot carrier transport properties. In particular, we predict that carrier lifetimes in perfect vanadium nitride could exceed that in silver, the best metallic conductor, by a factor of two! Accounting for their lower carrier velocties, carrier mean free paths are comparable to noble metals, while resistivities are within an order of magnitude (and comparable to elemental metals other than the noble metals). Combined with stability under extreme operating environments and low cost, our predictions indicate that TMNs are encouraging as future materials for efficient hot carrier extraction.