Abstract The search for nanoscale active electronic devices has been an important objective in nanoscience and nanotechnology. In this study, the electronic and transport properties of the benzene-1,4-dithiol-molecule (BDT) and Au-atom-S-benzene-ring-O-(SBO)-Au-atom junctions and the Au-AlN(0001)-Au polar semiconductor junction have been calculated using the first-principles calculation method and a new integrated piecewise thermal equilibrium approach for the current. The current-voltage (I-V) and conductance-voltage (C-V) characteristic curves obtained for the Au-BDT-Au molecular junction agreed reasonably well with experimental ones. The study of Au-BDT-Au identifies that treating Au 5d electrons as core electrons and letting the S end of BDT be bonded to the Au surface directly overestimated the current. Calculated I-V characteristic curve revealed that the asymmetric Au-SBO-Au molecular junction has a pulse-like I-V characteristic curve with dual differential conductance, which resembled well the one observed experimentally. The analysis of the electronic structures showed that this dual differential conductance transport property was due to a subtle charge transfer at the electrode-molecule contacts. The calculated J-V characteristic curve of the Au-Al(0001)-Au junction shows coexistence of ohmic, switching effect and negative differential conductance. The electronic structure calculations show the existence of an intrinsic band tilt due to the polar nature of the AlN(0001) film, which gives rise to an asymmetric transport property of the junction and the presence of hole states at the N-surface side and interface states at the Al-surface side of the AlN film. The bias induced changes of the hole states, interface states and the states of the Al and N ions in central layers in the vicinity of the local chemical potential give rise to the interesting transport property of the Au-AlN(0001)-Au junction.

No description available.