Effect of metal contact size on the metal-semiconductor junction characteristics

Metal-semiconductor (M-S) contacts at subnanometer scale have exhibited interesting Schottky characteristics. The observed rectification behavior cannot be explained in the light of the conventional planar-Schottky model and needs to consider the Physics of nano-Schottky junction at very small dimensions. In this work, the effect of M-S contact size on the (1-V) characteristic is investigated. We used a modified nano-Schottky model to calculate the new depletion width, the enhanced surface potential, and the enhanced electric field at the interface which significantly affect the (I-V) characteristic. The experimental (I-V) plot for 7 nm metal tip was used to fit the parameters in the nano-Schottky model. The nano-Schottky model was used to simulate (I-V) plots for various diameters of metal tip contacts (7-100 nm). The results clearly demonstrate the transition in the (I-V) Schottky reversed rectification behavior from sub-10 nm contacts to the conventional (I-V) Schottky behavior at around 100 nm contacts.