Tunnel transport model in nitrogen doped disordered carbon superstructures

Abstract

This study illuminates the specific role of the nitrogen potential in relation to the Fermi level (EF) in nitrogen incorporated amorphous carbon (a–CN) superlattice structures. In a–CN systems, the variation of conductivity with nitrogen percentage has been found to be strongly non-linear due to the change of disorder level. Here, we investigate the effect of correlated carbon (C) and nitrogen (N) disorder in conjunction with the nitrogen potential through the analysis of transmission spectra, calculated using a tight binding Hamiltonian, which show two broad peaks related to these species. The characteristic time of transmission through N centers can be controlled through a combination of the N potential and correlated disorder. In particular, by controlling the arrangement of the nitrogen sites within the sp2−C clusters as well as their energetic position compared to EF, a crossover of the pronounced transmission peaks of N and C sites can be achieved. Furthermore, N incorporated as a potential barrier can also enhance the transmission in the a–CN superlattice structures. The strong non-linear variation of resistance and the characteristic time of the structures can explain the transport features observed experimentally in a–CN films. These results will find application in the design of new a–CN fast-switching devices, whose characteristics can be tuned by the nitrogen potential and associated structural disorder.