Schematic of MMS device used for capacitance measurements and molecular modifiers used in this experiment. (B-benz), (D-benz), (M-benz), (N-benz), 2M 4N-benz.
(a) Typical curves for gold/molecule/ Si devices and (b) typical vs characteristic and linear fit of a representative MMS device.
Measured Schottky barrier height as a function of isolated molecule dipole moment for a series of MMS diodes.
Schematic of structure used to calculate MMS molecular-electronic properties. is the spacing between the topmost heavy atom on the molecule and the gold cluster.
Calculated potential profiles across molecule for (a) molecule/gold spacing and (b) molecule/gold spacing. The legend in (a) is applicable to both plots.
Calculated potential drop across molecule as a function of isolated molecule dipole.
(a) Schematic of the charge distribution and resulting potential profile in a MMS device and (b) flowchart illustrating self-consistent Poisson solution methodology for MMS diodes. is the electric field, is the permittivity, and is a weighting factor that is used for convergence purposes. The molecular charge density, interface trap charge, and semiconductor depletion charge can all be incorporated in .
Band diagram of MMS device. The actual barrier height differs from the built-in potential because of the change in potential across the molecular layer due to molecular capacitive effects and molecular dipole effects and the change in potential across the first few atomic layers at the Si surface due to interface charge .
Representative simulated curves for MMS devices. The discreteness in the curves is due to the simulation grid and the presence of large charge densities varying over small distances.
Effect of interface state density on apparent (a) barrier height and (b) doping density. The legend in (b) applies to both graphs.
Comparison of barrier height as measured by and calculated changes in Si surface potential.
Doping densities and Schottky barrier heights for gold/molecule/ Si devices as determined from measurements.
Calculated dipole moments (Debye) perpendicular to the Si surface for isolated molecular species used in this study assuming that the molecules orient perpendicular to the surface.
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