Distinct Mechanisms of DNA Sensing Based on N‐Doped Carbon Nanotubes with Enhanced Conductance and Chemical Selectivity

N‐doped capped carbon nanotube (CNT) electrodes applied to DNA sequencing are studied by first‐principles calculations. For the face‐on nucleobase junction configurations, a conventional conductance ordering is obtained where the largest signal results from guanine according to its high highest occupied molecular orbital (HOMO) level, whereas for the edge‐on counterparts a distinct conductance ordering is observed where the low‐HOMO thymine provides the largest signal. The edge‐on mode is shown to operate based on a novel molecular sensing mechanism that reflects the chemical connectivity between N‐doped CNT caps that can act both as electron donors and electron acceptors and DNA functional groups that include the hyperconjugated thymine methyl group.