Landauer conductance of tunnel junctions: strong impact from boundary conditions

Strong conductance variation in conformationally constrained oligosilane tunnel junctions.

The effects of molecular conformation on conductance in oligosilane-bridged metal-molecule-metal junctions are studied theoretically using density functional theory combined with a nonequilibrium Green's function approach. Varying the internal SiSiSiSi dihedral angles in hexasilane diamine chains changes the conductance by up to 3 orders of magnitude. This conformational dependence is due to th...

Local Impurity-Assisted Conductance in Magnetic Tunnel Junctions

Observation of Strong Coulomb Blockade in Resistively Isolated Tunnel Junctions

We report measurements of the Coulomb-blockade current in resistively isolated (RIsol h/e2) tunnel junctions for the temperature range 60 mK < T < 230 mK where the charging energy Ec is much greater than the thermal energy. A zero-bias resistance R0 of up to 10RT (the tunnel resistance of the bare junction) is obtained. For eV Ec, the IV curves for a given RIsol scale as a function of V /T , wi...

Simulating Si multiple tunnel junctions from pinch-off to ohmic conductance

Due to their compatibility with CMOS, multiple tunnel junctions (MTJs) are giving rise to an increasing interest in Coulomb blockade silicon devices, along with a higher demand for simulation. Whereas the operating principle has been known for a number of years, here we present new simulation results on MTJs, including geometric island size and island separation. Application of MTJ in a memory ...

The impact of barrier height distributions in tunnel junctions

We demonstrate that including continuous and discrete tunnel barrier height distributions in otherwise traditional tunneling formalisms enables straightforward modeling of several phenomena important to tunneling. Random barrier height inhomogeneities significantly impact the tunneling conductance, as evidenced by ideal tunneling models extracting faulty barrier parameters, with the incurred er...