Fig. 4.

Room-temperature reverse bias I–V curves of a PtSi/Porous Si junction in the air and when it is in contact with methanol. There is a remarkable difference in the IV curves. The threshold voltage for the single-electron transfer can be estimated by drawing two asymptotes to the curves, one at low and one at high voltages. Their intersection is a rough indication of the threshold voltage. In this case, the threshold voltage of the air has changed from −20.5 V to about −17 V for methanol. Notice that at the voltage of about −20 V the current has increased by about 0.3 mA from the air to methanol.