Structurally Driven Enhancement of Resonant Tunneling and Nanomechanical Properties in Diamond-like Carbon Superlattices

We report nitrogen-induced enhanced electron tunnel transport and improved nanomechanical properties in band gap-modulated nitrogen doped DLC (N-DLC) quantum superlattice (QSL) structures. The electrical characteristics of such superlattice devices revealed negative differential resistance (NDR) behavior. The interpretation of these measurements is supported by 1D tight binding calculations of disordered superlattice structures (chains), which include bond alternation in sp(3)-hybridized regions. Tandem theoretical and experimental analysis shows improved tunnel transport, which can be ascribed to nitrogen-driven structural modification of the N-DLC QSL structures, especially the increased sp(2) clustering that provides additional conduction paths throughout the network. The introduction of nitrogen also improved the nanomechanical properties, resulting in enhanced elastic recovery, hardness, and elastic modulus, which is unusual but is most likely due to the onset of cross-linking of the network. Moreover, the materials' stress of N-DLC QSL structures was reduced with the nitrogen doping. In general, the combination of enhanced electron tunnel transport and nanomechanical properties in N-DLC QSL structures/devices can open a platform for the development of a new class of cost-effective and mechanically robust advanced electronic devices for a wide range of applications.