Tunneling barrier height

The dependence of the logarithm of the tunneling current with respect to distance is a measure of the work function, or the tunneling barrier height (Garcia, 1986 Coombs and Pcthica, 1986). In fact, from Eq. (1.12),... 

When the applied biases exceed the tunneling barrier height Ob, then cold-electron emission through a trapezoidal barrier can also occur from the electrode with greater surface roughness (e.g., the top electrode). This "field" emission is described by the Fowler30 -Nordheim3 [18] equation ... 

Investigation of local tunneling barrier heights Experimental... 

In one of the first publications on STM, Binnig and Rohrer discussed the possibility of recording the local tunneling barrier height K by a modulation experiment [9]. Their result can be summarized with the following equation ... 

Fig. 4. Mean tunneling barrier height vs. substrate potential on iron in a boron buffer solution.

The formation of an oxide layer leads to lower tunneling barrier height. 

Fig. 6. Measured tunneling barrier height on DIN 1.4301 and 1.4529 in 0.01 M sulfuric acid at = 0 mV, covered by an oxide film.

As one can see, the effective tunnel barrier height decreases with increasing number of intermediate states n and so depends on the oxide or adsorbate coating (Fig.3). 

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