Doping-dependent negative differential resistance in hybrid organic/inorganic Si-porphyrin-Si junctions.

Quantum transport properties of porphyrin-bridged p-n junctions with Si leads are investigated by ab initio calculations. It is shown that this system exhibits strong negative differential resistance (NDR) peaks, whose magnitude and position can be controlled by the doping levels of the leads and by changing the central transition metal atom of the porphyrin. These results are explained by bias-induced on-off switching of resonant tunneling channels associated with specific molecular orbitals. The predicted behavior is general and should be observable for other organic molecules bridging doped semiconducting leads.