Interfacial disorder and optoelectronic properties of diamond nanocrystals

Abstract

We present in this work a theoretical framework based on the tight-binding method, which is able to probe at a local atomic level the optoelectronic response of nanomaterial systems and link it to the associated disorder. We apply this methodology to carbon nanocomposites containing diamond nanocrystals. We find that significant structural and topological disorder exists at the interface between the nanodiamonds and the embedding amorphous carbon matrix. This can be quantitatively probed by extracting the Urbach energies from the optical parameters. Disorder in the nanocrystals appears in their outer shell near the interface and is manifested as bond length and angle distortions. Energetics and stability analysis show that nanodiamonds embedded in matrices with high density and high fraction of fourfold coordinated atoms are more stable.